Proceedings of 8th workshop for RNAS+
The 8the workshop for RNAS+ was held in linkage with the XVIIth International Congress for
Tropical Medicine and Malaria (ICTM2008) in, Korea from Monday, September 29, 2008 to Friday,
October 3, 2008. A total of three series sessions were arranged for the workshop, and 18 oral
presentations were presented to demonstrate the progress in research and control of the RNAS+
targeted diseases. Here, the abstracts of the presentations were complied with the efforts from Lydia
Leonardo, Professor of the University of Philippines.
At the same time, the board member meeting was held in the afternoon of September 30, 2008 in the
venue of the conference. The annual work plan was agreed with all board members of RNAS+.
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Presentations
RNAS+: A win-win collaboration to combat neglected tropical diseases in Southeast Asia ................. 3
Rethinking the Burden of Schistosomiasis and its Links to Poverty ...................................................... 4
National Prevalence Survey of Schistosomiasis in the Philippines ........................................................ 7
Assessment of the age-specific disability weights of early and late stages of chronic schistosomiasis
japonica in China .................................................................................................................................... 9
Summary of Nutritional Outcomes and Anemia Related to S. japonicum and Geo-helminth Infections
in Leyte, the Philippines........................................................................................................................ 13
Epidemiology and Control of Schistosomiasis in Indonesia ................................................................. 14
Recent situation and next steps of schistosomiasis control programs in Southeast Asia ..................... 15
Success Story of Schistosomiasis & Helminthiasis Control in Cambodia .......................................... 18
The comparison of ultrasonographic, serologic and coprologic examination of schistosomiasis
japonica patients in Sorsogon, the Philippines ..................................................................................... 22
Modeling the dynamics and control of transmissions of Schistosoma japonicum and S. mekongi in
Southeast Asia ....................................................................................................................................... 23
An Update of Schistosoma mekongi and Opisthorchiasis situation in Lao PDR................................. 25
New Tools for Treatment and Prophylaxis ........................................................................................... 27
Identification of New Drug Leads for the Control of Schistosomiasis ................................................. 28
Molecular characterization of Schistosoma japonicum tegument protein tetraspanin-2: Sequence
variation and possible implications for immune evasion ...................................................................... 31
Human Schistosoma japonicum Infection in Pregnancy (a pilot study)................................................ 32
Effects of schistosome infections on immunodeficiency virus transmission and progression.............. 34
Evaluation of a rapid strip testdetecting a parasite antigen (CCA) in urine for diagnosis of active
schistosomiasisin the field .................................................................................................................... 36
Antibody isotype responses to paramyosin, a vaccine candidate for schistosomiasis, and their
correlations with resistance and fibrosis in patients with Schistosoma japonicum in Leyte, The
Philippines............................................................................................................................................. 37
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RNAS+: A win-win collaboration to combat neglected tropical diseases in Southeast
Asia
Xiao-Nong Zhou, Nobuo Ohta, Jürg Utzinger, Robert Bergquist and Remigio M. Olveda
Presentor: Dr. Zhou Xiaonong
Dr. Zhou Xiaonong presented the history and development of RNAS+ (or the
Regional Network for Research, Control and Surveillance on Asian Schistosomiasis and
other helminthic zoonoses).
The network was first called Regional Network for research, control and
surveillance on Asian Schistosomiasis (RNAS). It was initiated in 1998 and assisted by a
collaborative research grant from TDR in 1999. The first RNAS working group meeting
was held in Philippines in 2000. Dr Feng Zheng, former director of Institute of Parasitic
Diseases was elected chair and and Dr Remigio Olveda, executive director of the
Research Institute for Tropical Medicine in the Philippines, the co-chair.
The three stages that RNAS went through were described by Dr. Zhou as
1 stage: Coming together is a beginning
2nd stage: Keeping together is progress
3rd stage: Working together is success
st
At present, RNAS is composed of representatives from Lao PDR, China, Thailand,
Indonesia, Philippines, Japan, Vietnam, Korea and Cambodia. The network has met
seven times. In September 1998, it was conceptualized in Jiangsu, People’s Republic of
China. It was formally organized in Tagaytay, the Philippines in 2000. The 2nd meeting
was in again in Jiangsu, PR China in July 2001. The 3rd RNAS meeting was in Phnom
Penh, Cambodia in May 2002. The 4th meeting was in Vientiane, Lao PDR in November
2003. The 5th was in Bali, Indonesia in August 2005. The 6th was in Bohol, Philippines in
September 2006. The 7th meeting was back in China in Lijiang in September 2007.
During the first stage of RNAS history when the network was established (19992001), its aim of promoting collaboration among scientists in the field of Schistosoma
japonicum research was envisioned through.
1. Establishment of communication among scientists on S.japonicum research by
establishing a network homepage.
2. Exchange information between Chinese and Philippine scientists through regular
scientific meetings.
3. Share technologies and experience in diagnosis, surveillance and control
The second stage (2001-2005) is marked by strengthening of the organization with
the following objectives.
1. strengthening communication among scientists working on Asian schistosomiasis
through RNAS network;
2. sharing developed technologies on diagnosis and surveys of Asian
schistosomiasis through collaboration research activities and training activities in
endemic areas.
3
Two grants from WHO-TDR were obtained through the efforts of the chair Dr Feng
Zheng and Dr Remigio Olveda. Additional support came from the Danish Bilharzhiasis
Laboratory.
The number of participants who attended the meetings increased with every meeting
from 20 in 2000 in the Philippines to 38 in 2001 in China to 70 in 2002 in Cambodia to
80 in Laos in 2004 and Indonesia in 2005 to 109 in 2006 in the Philippines and 200 in
the last meeting in Lijiang, PR China.
communication of knowledge concerning Asian schistosomiasis

2) providing direct scientific and operational exchange and collaboration at
the regional level,

3) sharing technologies for surveillance, prevention and control.
33-1
Rethinking the Burden of Schistosomiasis and its Links to Poverty
Charles H. King MD
Professor of International Health
Center for Global Health and Diseases
Case Western Reserve University
Cleveland, Ohio USA
The presentation included why it is important to have an accurate assessment of
disease burden; how World Bank, WHO and other policymakers have assessed burden;
the Global Burden of Disease (GBD) Project; Disability-Adjusted Life Year (DALY);
why GBD was inaccurate for NTDs and why DALY-based analysis doesn’t work well in
resource-poor areas.
The GBD Project and Disease Control Priorities Project chose the DALY for
comparing and then ranking the global ‘importance’ of specific health conditions. DALY
is a mathematical construct calculated as = Years of Life Lost + Years Lost to Disability
for individuals having a specific health condition.
The reason why disabilities are quantified is because policy-makers and donors
wish to provide maximum benefits for the resources that are expended, i.e., maximize
cost-effectiveness of funds spent: The Incremental Cost-effectiveness Ratio (ICER)
= [cost1-cost2] / [DALY1-DALY2]. This was the impetus for DALY rankings in the
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Global Burden of Disease Project. Resources are limited. So the question of whether it is
a necessity or a luxury to treat helminthiasis is important. A higher disease burden means
a greater priority to treat or prevent.
There are hidden assumptions of the DALY-ICER approach. First, there is an
‘average’ disability for each disease state in any country or location in the world. There is
a linear association between resource investment into a control program and the resulting
improvements in terms of reductions in disease burden
In the GBD, “We must assume that ‘Like is Like’ for the same disease in
all parts of the world. ” The ‘fungible’ nature of goods is a basic economic concept. An
example for GBD assessment is “What is the burden of disease for the ‘average’ person
with schistosomiasis?”
In the DALY Person-trade-off method of disability weight determination, there is
a Deliberative Panel’s ranking of diseases for their disability weights. Dw=0 if one is in
good health and Dw=1 for death in the other extreme. Between the two extremes are the
following diseases or disabilities ranked from lowest to highest: Goitre, Diarrhea,
Malaria, Paraplegia and Coma.
To the question “what’s the problem with having worms?” The old school would
consider worm parasitism as non-lethal with only very few getting sick. It is also
minimally symptomatic and unavoidable in less-developed settings. In the DALY Person
trade-off method of disability determination, schistosomiasis has a Dw equal to 0.005
which puts it between goiter and good health. The new wave of thought would consider
worm parasitism as chronic/recurrent infections which mean with long-term ‘subtle’ or
insidious morbidity and resulting in developmental and physical disabilities.
An evidence-based assessment would seek the available evidence about
schistosomiasis disability. Schistosomiasis causes chronic inflammation. It can last for
decades. While it has low mortality it has daily morbidity.
A meta-analysis of disability-associated outcomes in schistosomiasis by
King, Dickman, & Tisch, Lancet 2005 listed the following.
•Exercise intolerance
•Work yield
•School performance
•Personal care
•Religious activity
•Pain
•Diarrhea
•Infertility
•Health care needs
•Anemia
•Weight deficit
•Height deficit
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•Skin-fold thickness
•BMI
•Serum protein
•Vitamin A levels
•VO2max deficit
•Cognition deficit
Meta-analysis also showed relationship between schistosomiasis infection status
and anemia. Schistosomiasis means hemoglobin deficits. The average difference = 4
gm/L. Anemia is worsened by low SES and diet quality. Schistosomiasis reduces
average Hb to less than 120 gm/L. These levels associated with 3-5% reduction in work
output and 60% reduction in peak workload capacity (Guyatt H, Parasitol Today, 2000).
By basic DALY computations, a 20% disability for 26 weeks and a 2% disability for 5
years are equivalent. A 20% disability for 26 weeks may be more visible than a 2%
disability for 5 years. This is because small’ values are more difficult to measure
objectively, but may be highly significant to the patient in causing their disability.
Some misperceptions have to be corrected. Anemia does not have to be severe to
be disabling. Mild ‘chronic disease’ anemia is significant in terms of endurance, income,
birth outcomes. Undernutrition does not have to be severe to be disabling. Even
‘minimal’ disability is highly significant in the rural poverty setting. Schistosomiasis is
associated with at least a 4%-15% disability.
For the schistosomiasis disability weight, King, et al. (2005) found 4-15%
disability based on anemia impact on productivity and comparison to similar chronic
inflammatory disorders. Finkelstein, et al. (2008) wrote 10-19% disability for S.
japonicum based on life-path probabilities for morbid complications while Jia, et al.
(2007) found 10-25% disability for S. japonicum, based on Quality-of-Life measures.
In summary, based just on unacknowledged disabling impact of infection, the
DALY calculation for schistosomiasis (and other NTDs) was wrong, underestimating
schistosomiasis DALYs by 8 to 50-fold. To the question “For this kind of disability, is
there a worldwide ‘average’ disease burden for schistosomiasis?” The answer is No.
There is NOT an ‘average’ disease burden for schistosomiasis. The assigned Dw does not
capture the true burden of schistosomiasis. The assumption of average fails because of
the hidden stratification. No valid ‘average’ may exist across age, gender, location and
SES.
The ‘Barbell’ distribution of wealth means there is no average disability. An asymmetric
outlook on health costs and program gains was presented. As a result of this “Like is
NOT Like.” And therefore the relative utility of goods depend strongly on context. The
poverty trap adapted from Sachs, The End of Poverty, 2005 was shown including the
effect of disability on the poverty trap. In the context of poverty there are non-linear
differences in the leverage of treatment on health outcomes. Individual poverty and
residence in an impoverished environment combine synergistically to impair
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improvement from single health interventions. Co-morbidities are important effect
modifiers.
These non-linearities mean full control will require more intensive efforts to
eliminate transmission and disease which is bad. Benefits of treatment can be synergistic,
providing greater health benefits than predicted by DALY models which is very good.
In summary, worm infection is an integral part of the ‘Poverty Trap’. Preventive
therapy and worm elimination will be an essential part of achieving development goals.
The remaining questions: include the need for the best possible prevalence data in all
areas; the need for longitudinal data on treatment outcomes; what are disability
reductions from treatment such as growth, hemoglobin, education; community-wide;
transmission reduction; maternal/fetal health and survival and fertility, sexual
dysfunction. Another questions is “Is the DALY still an appropriate metric for policy
decisions? The links to poverty such as impact on individual, family and community, and
synergistic benefits to be gained by treatment should also be answered.
33-2
National Prevalence Survey of Schistosomiasis in the Philippines
Lydia R. Leonardo, DrPH
College of Public Health
University of the Philippines Manila
The national prevalence survey of schistosomiasis in the philippines was divided
into three phases namely Phase I in Mindanao completed in 2005; Phase II in the
Visayas in 2006 and Phase III in Luzon in 2007.
The project was developed after several consultative meetings among Dr. Rahman
Velayudhan from the World Health Organization; Dr. Mario Baquilod, Dr. Leda
Hernandez, Ms. Ruth Martinez from the National Center for Disease Prevention and
Control; Dr. Vito Roque, Mr. Herdie Hizon of the National Epidemiology Center; Dr.
Gemiliano Aligui of the Philippine Council for Health Research and Development and
from the College of Public Health Dr. Lydia Leonardo, Dr. Pilarita Rivera and Dr.Ofelia
Saniel.
During the consultative meetings, consensus was reached on the following issues.
Sample size was based on prevalence rates determined from the 1994 Philippine Health
Development Program. Sampling design used was stratified two-step systematic cluster
sampling design. Two Kato-Katz stool exams were done based on two stool samples
collected on two separate days. Quality assurance was done in the form of Lot Quality
Assurance Sampling.
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For the rationale, accurate and reliable prevalence figures are needed to determine
the disease situation in community which in turn determine the nature of intervention to
be implemented. The goal is to classify schistosomiasis endemic areas into high,
moderate and low prevalence areas. The objectives are to determine the prevalence rate
of schistosomiasis in Mindanao and the Visayas and to set up a reporting system and a
data base for schistosomiasis through the schistosomiasis reporting system. The
collaborating agencies are the College of Public Health, the Department of Health and the
World Health Organization.
The activities included consultative meeting with regional coordinators involved
in the survey, the actual survey, monitoring visits, encoding of data, validation of KatoKatz results and lastly writing of the report.
The sampling design used was stratified two-stage systematic cluster sampling.
Stratification was done by region and prevalence level. The 42 provinces were
categorized first into regions where they belong. The provinces classified into high,
moderate and low prevalence. All provinces with high and moderate prevalence included
in survey. Random selection done in provinces with low prevalence. Provinces were
primary sampling units and barangays the secondary sampling units. Households were
selected in a systematic manner. Eligible members referred to those whose age is two
years and above.
The survey team consisted of barangay health workers who took care of
informing the population to be surveyed and distributing stool cups to households
concerned and collected them. The microscopists prepared stools for Kato-Katz
examination, read the slides and recorded results.
Kato-Katz examination was used to diagnose schistosomiasis and detect presence
of eggs of other parasites. Two stools were collected on two separate days. Also recorded
were soil-transmitted helminthes, heterophyids, echinostomes and pinworms. The KatoKatz slides kept for Lot Quality Assurance System.
The prevalence of schistosomiasis by province was shown with Agusan del Sus
topping the list followed by Northern Samar and then Eastern Samar for the top three
provinces. Prevalence by province was shown with Region 13 as number 1 in prevalence.
A GIS map of the distribution of schistosomiasis showed the endemic areas found mostly
on the southeastern side of the country. Age distribution of the disease in the three island
groups show that the age groups mostly affected are the older age groups or the working
age groups. Sex distribution in the three island groups show the higher prevalence of the
disease among the males compared to the females.
The prevalence of other helminthes such as STH and hetrophyidiasis was also
shown. Prevalence of ascariasis and trichuriasis is highest in the Visayas while
hookworm and heterophyidiasis predominated in Mindanao. When ranked according to
the magnitude of helminthic problem, Mindanao and the Visayas were of the same rank
with Luzon a far second.
8
Given the results of the survey, the following recommendation was made. There
should be an integrated approach to target fecal-borne parasitic infections to include
chemotherapy, environmental sanitation and health education.
33-3
Assessment of the age-specific disability weights of early and late stages of chronic
schistosomiasis japonica in China
Tie-Wu Jia1, Xiao-Nong Zhou1, Jürg Utzinger2, Xiao-Hua Wu1
1 National Institute of Parasitic Diseases, China CDC, Shanghai, China
2 Swiss Tropical Institute, Basel, Switzerland
Before the 7th RNAS+ workshop in Lijiang, China, the following papers were
available on the burden of disease of schistosomiasis.
 2002：World Health Organization. Prevention and control of schistosomiasis and
soil-transmitted helminthiasis. World Health Organ Tech Rep Ser 912. Geneva:
WHO, 2002: 1-57.
 2004：Michaud CM, Gordon WS, Reich MR, eds. The global burden of disease
due to schistosomiasis: schistosomiasis research program working paper series.
Cambridge, MA, USA: Harvard Center for Population and Development Studies,
Harvard School of Public Health, 2004: 1–41.
 2005：King CH, Dickman K, Tisch DJ. Reassessment of the cost of chronic
helmintic infection: a meta-analysis of disability-related outcomes in endemic
schistosomiasis. The Lancet, 2005, 365(9470):1561-1569.
 2005: King CH, Quantification of disease burden due to Schistosomiasis. in:
Scientific Working Group. Report on Schistosomiasis 2005, Geneva: WHO
Special Programme. 47-52.
 2005：Finkelstein JL, McGarvey ST, Schleinitz DM. Re-investigating the global
burden of disease due to Schistosoma japonicum. Am J Trop Med Hyg, 2005, 73
(354th Annual Meeting Supplement):341.
 2007：Jia TW, Zhou XN, Wang XH, et al. Assessment of the age-specific
disability weight of chronic schistosomiasis japonica. Bull World Health Organ,
2007, 85(6):458-465.
After that workshop in Lijiang, China, the following papers came out.
 2007: Mathers CD, Ezzati M, Lopez AD. Measuring the burden of neglected
tropical diseases: the global burden of disease framework. PLoS Negl Trop Dis,
2007, 1(2):e114.
 2008: Finkelstein JL, Schleinitz MD, Carabin H, et al. Decision-model estimation
of the age-specific disability weight for schistosomiasis japonica: a systematic
review of the literature. PLoS Negl Trop Dis, 2008, 2(3):e158.
 2008: King CH, Dangerfield-Cha M. The unacknowledged impact of chronic
schistosomiasis. Chronic Illn, 2008, 4(1):65-79.
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 2008: King CH, Bertino AM. Asymmetries of poverty: why global burden of
disease valuations underestimate the burden of neglected tropical diseases. PLoS
Negl Trop Dis, 2008, 2(3):e209.
 2008: King CH. Schistosomiasis japonica: The DALYs Recaptured. PLoS Negl
Trop Dis, 2008, 2(3): e203.
The following issues on global burden of disease (GBD) study were mentioned. Agespecific disability weight due to schistosomiasis is very low (0.005-0.006). Same
disability weight is assigned to different schistosome species (S. haematobium, S.
mansoni and S. japonicum). Schistosome infection is considered as only sequelae, while
morbidity may persist long after parasitological cure (infection ≠ morbidity). The
seriously underestimated DWs lead to seriously underestimated disease burden of
schistosomiasis in GBD study.
A table on GBD cause categories, disabling sequelae and average disability
weights for malaria and neglected tropical diseases (NTDs) taken from PloS, 2007 was
shown. Another table on tropical diseases mortality and burden, priority and neglected
diseases of the world 2002 taken from a WHO report was also shown.
The objective of the present study is to estimate the age-specific disability weights
of early and late stages of chronic schistosomiasis japonica in China. The non-fatal health
outcomes of chronic schistosomiasis japonica (early stage) were presented as follows. For
direct morbidity the signs are abdominal pain, blood in the stool and bloody diarrhea and
the symptoms are hepatomegaly, splenomegaly and hepatic fibrosis. For indirect
morbidity, the nutritional impairments include anaemia, malnutrition and growth
retardation while the functional impairments are educational impairment, productivity
loss and exercise intolerance.
The advanced/late-stage schistosomiasis japonica can be regarded as an extreme
type of chronic schistosomiasis japonica, of which the clinical presentations are similar to
hepatosplenic disease of S. mansoni infection. In China, advanced schistosomiasis is
defined as a chronic condition with portal hypertension syndrome after hepatic fibrosis,
severe growth retardation, or granulomatous disease of the large intestine.Based on the
main symptoms, it can be classified into four clinical types, namely (i) ascites, (ii)
megalosplenia, (iii) colonic tumorid proliferation and (iv) dwarfism.
Photographs of advanced cases of schistosomiasis in the 1950s were shown and
compared with advanced cases in 2000.
For the study time, area and sampling, the early stage cases were sampled using
grid sampling in 2004-2005 from Dangtu county of Anhui province and Hanshou county
of Hunan province. The late stage cases were sampled using cluster sampling in 20072008 only in Hanshou county of Hunan province. In Dangtu, Anhui, the number of
endemic villages included was 25 and 15 for the non-endemic villages. In Hanshou,
Hunan, the number of endemic villages is 31 while the number of non-endemic villages
is 20. The EQ-5D plus cognition questionnaire (EQ-6D) was presented.
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Field surveys included household survey, ELISA, ultrasound examination and
interviews using individual questionnaire. For statistical analysis, two multivariate
regression models will be developed to explore the morbidity indicators associated with
DW. Model 1 will evaluate the relationship between the variables of the EQ-5D plus
questionnaire and DW, whilst model 2 will assess the correlation between morbidity
indicators, socio-economic status and DW.
The diagnosis criteria of chronic schistosomiasis japonica include:
(i) positive serological result,
(ii) self-reported contact with potentially schistosome-infested water, and
(iii) either schistosomiasis-like hepatic fibrosis of grade II–III as detected by
ultrasonography, or no or light hepatic fibrosis (grade 0 or I) with the presence of
hepatomegaly or splenomegaly.
For the results of the survey of cases of early schistosomiasis, 91 villages with
estimated population of 134,385 were surveyed. Two-thirds lived in home village for
>6 months in 2004. The eligible population was 77,387 (aged >5 years). The number
screened by ELISA was 59,765. The number found positive by ELISA was 3,405
(5.7%). The number of sero-positive with complete questionnaire results was 2,843. 1419
of the 2843 seropositive participants (49.9%) fitted the criteria of chronic schistosomiasis
japonica. A table showing the distribution of signs of early schistosomiasis by age
groups was shown. Another table showing the distribution of symptoms by age groups
was presented. Another table showing the perceived quality of life of the cases was
presented. The age-specific disability weights for early stage of chronic schistosoma
japonica were presented.
Based on the multilevel regression models, disability weight is significantly
associated with sex, grade of hepatic fibrosis, hepatomegaly, abdominal pain, blood in
stool, impaired working/study capacity and cognition.
For the results of the survey on cases of late stage schistosomiasis, 506 were
suspected out of the officially registered cases who were screened and 215 cases were
confirmed. Other results are as follows.
oDemographic characteristics
1. Sex
Male: 71.6% (154/215), female: 28.4% (61/215)
2. Age: 57.06±12.56 (30,81)
3. Occupation
Farmer:92.6% (199/215)
Fisherman/boatman: 2.8% (6/215)
Businessman/worker/civil servant: 4.7% (10/215)
oClinical types
1. Ascites: 64.19% (138/215)
2. Megalosplenia: 34.42% (74/215)
3. Colonic tumorid proliferation: 0.47% (1/215)
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4. Dwarfism: 0.93% (2/215)
Tables showing the following results were presented: distribution of signs and
symptoms of late schistosomiasis by age groups; results of examinations and tests by age
groups; dimensions of quality of life such as mobility, self-care, usual activities,
pain/discomfort, anxiety/depression, cognition as perceived by the cases as none,
moderate or extreme by the cases; the distribution of the dimensions of quality of life
according to age groups; and age-specific disability weights for late stage chronic
schistosomiasis japonica.
Multivariate regression models show that disability weight was significantly
associated with loss of work capacity, moderate/severe ascites, positive of HbeAg and
having splenectomy and high albumin level were protective factors.
The following conclusions were drawn from the study.
•Disability weight of chronic schistosomiasis japonica is really high (mean: 0.191 for
early stage, 0.447 for late stage)
•Disability weight increases with age (0.095 to 0.246 for early stage, 0.378 to 0.510 for
late stage)
•For late stage cases, the functional performances such as mobility and usual activities
were deeply impaired.
The study recommended that a reappraisal of the disability weights due to chronic
schistosomiasis mansoni and schistosomiasis haematobia be done as well as a reestimation of the global burden of schistosomiasis.
Future research directions include the following.
1) Assessing the need to explicitly address additional diseases not currently included in
the GBD. The current draft cause list for the GBD 2005 also includes cysticercosis,
echinococcosis, dracunculiasis, yellow fever, rabies, and leptospirosis.
2) Review of the disease sequelae quantified for each disease to ensure that all important
disabling outcomes are captured, and also that the natural history of the disease is
appropriately modeled.
3) Development of improved disease models for the estimation of incidence and duration.
For several important diseases, the current GBD study does not attempt to estimate
incidence, and effectively assumes that incidence equals prevalence for the calculation of
YLDs.
4) Comprehensive revision of disability weights for disabling sequelae incorporating
population-level information on the distribution of health states.
5) Addressing the issue of so-called subtle morbidity, i.e., small decrements in
functioning (e.g., fatigue) associated with chronic infection.
6) Development of methods for the assessment of disability weights for highly prevalent
impairments or sequelae of low average severity (e.g., anemia, cognitive deficits).
7) Development of methods to ensure that disease-specific estimates of impairments
common to a number of disease and injury causes, such as anemia or cognitive deficits,
collectively match population-level total prevalences for such impairments.
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8) Addressing the difficult issues of assessing the incidence and prevalence of highly
focal diseases. Studies tend to focus on areas with disease—how representative are these
studies of the whole population at-risk, what populations are at risk, how to extrapolate to
national, regional, and global estimates of incidence and prevalence?
9) Estimating attributable deaths due to NTDs for long-term outcomes such as cancers,
cirrhosis of the liver, and renal failure.
10) Estimating cause-specific mortality for diseases with relatively low case fatality rates
in regions without useable death registration data. Innovative new approaches to the use
and validation of verbal autopsy instruments may be helpful.
11) Identifying key risk factors for NTD incidence and mortality, quantifying exposure
distributions for individual and multiple risk factors, and quantifying their hazardous
effects, especially when the hazardous effects may depend on the presence of other risks
(Mathers CD, 2007).
33-4
Summary of Nutritional Outcomes and Anemia Related to S. japonicum and Geohelminth Infections in Leyte, the Philippines
Remigio M. Olveda, M.D.
Research Institute for Tropical Medicine
Department of Health
Philippines
The mechanisms of schistosomiasis-associated anemia include extra-corporal
blood loss, sequestration of RBC’s in spleen, autoimmune hemolysis, anemia of
inflammation (trapped eggs), decreased erythropoiesis, decreased erythrocyte lifespan,
iron metabolism shifts to storage and hepcidin influences on iron-efflux from intestinal
epithelium and macrophages.
The mean adjusted hemoglobin by intensity of helminth infections was shown.
The odds of occult blood loss by helminth infection intensity can be udnersttod as
follows. Heavy intensity S. japonicum infection associated with 3.54 times risk of stool
occult blood positivity versus uninfected, low and moderate. Heavy or moderate intensity
Trichuris infection is associated with 2.68 times risk of stool occult blood positivity
versus uninfected low. There is no association with hookworm intensity. Odds of occult
blood loss may be due to presence of N. americanus not A. duodenale.
S. japonicum intensity and adjusted mean hemoglobin was shown. Also presented
was S. japonicum intensity of infection and risk of occult blood loss. It was also shown
that S. japonicum intensity of infection is inversely related to height for age Z-score
among children less than age 12 after adjusting for key confounders.
Tables and graphs showed the following results:
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1. S. japonicum related hepatic fibrosis and nutritional status
2. S. japonicum and hepatic fibrosis by mean age and gender
3. S. japonicum, Proinflammation and Nutrition
4. S. japonicum Hepatic Fibrosis and IL-6 Production
5. S. japonicum hepatic fibrosis and inflammation
6. Improvement in Nutritional Status after treatment w/ PZQ
7. Improvement in hemoglobin after treatment w/ PZQ
8. Improvement in hemoglobin after treatment w/ PZQ is modified by re-infection
9. Improvement in long term growth 18 months after treatment w/ PZQ
10. Iron deficiency versus non-iron deficiency (anemia of inflammation) anemia at
varying levels of re-infection at 12 and 18 months
The study concluded that rapid reinfection led to a reversal of the positive
treatment effect on Hb. In setting of high prevalence of scistosomiasis japonica (~60%)
approx. 20% of all-cause anemia due to S. japonicum. Principle mechanism of S.
japonicum-associated anemia is pro-inflammatory cytokine mediated anemia. Iron
deficiency plays an additional role in moderate/high intensity infections.
S-39
39-2
Epidemiology and Control of Schistosomiasis in Indonesia
Mohammad Sudomo¹, Jastal², Triwibowo A. Garjito², Mujiyanto², Hayani Anastasia²,
Sitti Chadijah²
WHO Indonesia¹, VBDRU Donggala, Natl. Inst. Of Health Research & Dev., MoH
Indonesia²
Schistosomiasis is presently distributed only in Central Sulawesi in Napu and
Lindu Valleys. In Lindu Valley, 8 villages around the lake are endemic. The snail foci are
concentrated in North Lore where 17 villages are endemic. In Central Lore, only two
villages are endemic. A new focus was found in South Lore. Schistosomaisis was first
found Lindu valley in 1935 by a Dutch doctor named Tesch. Before control was started,
the prevalence was very high. In lindu valley it averaged at 37% in 1974 and in Napu
Valley the prevalence was as high as 72% in the village of Winowanga in 1974.
The snail intermediate host was found in 1971 in an abandonned rice field. It was
identified as sub species of Oncomelania hupensis, O.h.lindoensis. Humans are infected
when they have contact with contaminated water. Adult schistosomes live in hepatic
portal vein and mesenteric vein.Beside humans, S. japonicum also infects other mammals
in the valley such as rats, dog, deer, wild boar, cow, horse, civet cat, etc.
Snails are widely but focally distributed around the valleys. Two different snail
habitat have been identified namely disturbed and natural habitats. Disturbed habitats
consist of abandoned rice fields along the ditches. Natural habitats are wet lands under
big trees, at the lake shores, forest edges, under tall grass (wild sugar canes).
14
Schistosomiasis control began in 1974 with different kind of methods like
treatment with niridazole; snail,control using bayluscide and agroengineering. The
prevalence was decreased from 74% to 25% in one village of Anca in Lindu Valley.
Niridazole is very toxic with severe side effects and treatment is for 7 days continuously.
The use of niridazole was eventually stopped and the programme was then changed into
more intensive control.
A more intensive and coordinated control was implemented in both endemic
areas. Mass drug administration using praziquantel 60 mg/kg.bw, divided into two and
taken with 4-6 hours was adopted. Snail control, provision of clean water and provision
of family latrines were implemented. Evaluation of the programmes was done every six
months through a routine surveillance. Stool examination was done every 6 months. Rat
trappings and examination of rat feces for schistosome eggs were performed. Snail
examination for presence of cercariae and sporocysts was also conducted.The results
were very good decreasing the prevalence significantly but reinfection continues.
Transmission cycle is still going on especially the sylvatic cycle.
The Central Sulawesi Integrated Area Development and Conservation Project (or
the CSIADCP) was began in 1999 through the support of an Asiand Development Bank
loan. It is a multi-sectoral project with the health sector incorporated only in 2001. The
objective of the project is to develop the schistosomiasis endemic areas as well as the
Lore-Lindu national park conservation. Since then schistosomiasis control became more
intensive and well directed. Provision of family latrines and water supply were
intensified. Schistosomiasis control by using integrated control measures such as mass
drug administration, followed by selective treatments, snail foci control was intensified.
All activities involved community participations. Mapping of the snail distribution was
also initiated. Evaluation was conducted every 6 months. A table was presented showing
the different phases of the control program and the activities in each phase. The
schistosomiasis situation in Central Sulawesi was shown including infection rates in
humans, rats and snails.
In 2002, two snail foci were found in South Lore in 2 villages. Rats were positive
for S. japonicum but no human cases were found. In 2008 Cercariae were found in snails.
Cases were found. Rats were found positive. To date survey in those villages is still in
progress.
39-1
Recent situation and next steps of schistosomiasis control programs in Southeast
Asia
Ohmae H*, Olveda R**, Socheat D***, Sudomo M****,
Chigusa Y*****, Matsuda H*****
* Department of Parasitology, National Institute of Infectious
15
Diseases, Japan
** Research Institute of Tropical Medicine, The Philippines
*** National Center for Malaria control, Parasitology and
Entomology, Cambodia
**** CSR, WHO country office, Indonesia
***** Center of Tropical Medicine and Parasitology, School of
Medicine, Dokkyo University, Japan
The paper showed the past, recent and future situation of schistosomiasis in the
Philippines and Cambodia. This included climate factors and the intermediate snail hosts;
biological background of snail control; biological characteristics of intermediate snail
hosts; transmission patterns of cercariae; control measures; impact of mass treatment with
praziquantel(PZQ); integration in the next step of control program; reservoir hosts and
schistosomiasis as a zoonosis; monitoring; prevalence and morbidity and elimination.
In the Philippines, the main endemic areas of schistosomiasis japonica lie along
the Pacific coast. These areasno clear dry season except Mindoro and Bohol islands.
There are much underground water and many springs in Mindoro. Wet condition is good
for living of the snail host, Oncomelania quadrasi. The dry season in Bohol is not very
clear. Since the 1980s, control program including mass drug administration(MDA) with
PZQ has been intensive in the Philippines. Together with MDA, active snail control has
been carried out in Bohol. Some endemic foci have been recently found in Negros.
The characteristics of climate in schistosomiais endemic areas of the Philippines
was described. The intermediate snail host of S.japonicum in the Philippines is
O.quadrasi which is aquatic and cannot live under dry condition. In most of the endemic
areas of the Philippines, total rainfall of each month exceeds 100 mm and there is no
clear dry season. Non-endemic areas have a clear dry season.
Transmission areas include ricefields and banks of streams and swamps.
Transmission of S. japonicum is not seasonal and continues all throughout the year.
Selective MDA has been implemented in Bohol since 1981 and snail control since
1987. By selective mass treatment with PZQ every year, the prevalence of S.japonicum
infections decreased to approximately 6-8%, and the morbidity improved. By joint
program of selective mass treatment and snail control using molluscisides, the prevalence
dramatically decreased to less than 1% in Bohol.
Control of intermediate snail host of S. japonicum in Bohol is done by grass
cutting in swamps, use of molluscicides after grass cutting and land reformation from
swamps to rice-field. A task force is assigned to take care of the control program.
Endemic areas of schistosomiasis mekongi are found along the Mekong River.
Mekong schistosomiasis is endemic along the Mekong River in the border area of Laos
and Cambodia. Some clinical cases were reported in 1960s. Primary epidemiological
surveys were performed in 1970s. Because of confusion due to the Indochina war, they
16
have not had any control programs until MDA with PZQ coordinated by WPRO in Laos
in 1989. In Cambodia, the first national epidemiological survey was performed in 1995
and heavy endemic areas were reported in Kratie and Stung Treng provinces. Following a
pilot control project, schistosomiasis control activities scaled up to cover all the endemic
districts in 1996-1997.
The characteristic of climate of schistosomiasis endemic areas in Cambodia was
shown. The intermediate snail host of S. mekongi in Cambodia is Neotricula aperta. It is
very aquatic and lives in the big Mekong river. Cambodia has clear rainy and dry seasons
in Cambodia. There is no difference in the climate condition in endemic and non-endemic
areas of mekong schistosomiasis. Transmission areas of the Mekong river include the
river during the rainy season and around rocks during dry season.
The decrease in prevalence four sentinel villages in Kratie province was shown.
The prevalence of schistosomiasis mekongi as detected by Kato-Katz stool examination
rapidly decreased by MDA and no positive ones has been found since 2004 in the
sentinel villages. Improvement of morbidity as seen by change of palpable hepatomegaly among children in four sentinel villages in Kratie province was shown. After the
beginning of MDA, palpable hepatosplenomegaly has rapidly disappeared among the
children living in the endemic area. Two to three years after the beginning of MDA,
clinical symptoms and signs have become insufficient for monitoring changes of the
morbidity due to schistosomiasis mekongi.
A new tool for monitoring the morbidity has been found in ultrasonography in
schistosomiasis japonica. Ultrasonographic (US) findings are useful to monitor the
changes of morbidity due to schistosomiasis japonica. Type 3: Network pattern is a
characteristic pattern of advanced liver fibrosis and is found in some cases without
palpable hepatomegaly. The ratio of detection of this pattern in young village people may
be useful to monitor the morbidity.
Change in the intensity of S. japonicum infections after MDA and limitations of
stool examination for monitoring the prevalence were shown. Before therapeutic
interventions, the prevalence and intensity of schistosomiasis detected by stool
examinations are high in young males living in the endemic areas. After MDA, the
intensity (expressed in EPGs) has decreased and sensitivity of Kato-Katz stool
examination has become insufficient.
Comparison of control measures and effects in Bohol and Leyte using Kato-Katz
and COPT were shown. After selective MDA and snail control, positive rate of stool
examination has in Bohol. Following this decrease, positive rate of COPT also decreased
This trend may mean drastic decrease of new transmissions. After MDA, positive rate of
stool examinations decreased in Leyte. But positive rate of COPT did not change
indicating that new transmissions might be continuing in Leyte. Comparison of the
results of stool examinations and ELISA using the antigen of S. japonicum in S. mekongi
endemic villages in Kratie provinc in Cambodia was shown.
17
Some problems in the next step from morbidity control to elimination of
schistosomiasis in Southeast Asia were cited. For control measures, the interval and
targeted people of MDA should be sustained. There are still questions on whether
treatment should be done every year or every other year or should this be universal or
selected. MDA should also be integrated with other control measures such as snail
control and health education. There should also be integration of control programs of
schistosomiasis and other NTDs.
On the question of reservoir hosts and schistosomiasis as a zoonosis, there is a
need to compare S. japonicum and S. mekongi infections. The kinds of reservoir hosts are
few and the role is little in transmission of S. mekongi. The changes of infection rates of
reservoir hosts might be useful for monitoring new transmissions.
For monitoring, new adequate and sustainable indicators to monitor prevalence
and morbidity should be used. As progress of the control programs, present indicators
such as stool positive rate and clinical symptoms have become insufficient to evaluate
real situation. More sensitive methods for survey should be applied such as ELISA for
prevalence and US examinations for morbidity. Standardization and simplification may
be necessary in the next step.
The definition of elimination and its possibility should be clear.
An
adequate mathematical model is necessary for predicting elimination. The influence of
climate change or global warming such as changes in rainfall on the intermediate host
should be studied.
39-3
Success Story of Schistosomiasis & Helminthiasis Control in Cambodia
Dr. Duong Socheat,
Director, National Centre for Parasitology,
Entomology & Malaria Control
The intermediate host of Schistosoma mekongi is Neotricula aperta (gamma race).
It is an amphibious snail living in small crevices in partially submerged rocks in the
Mekong river and some of its tributaries. Transmission occurs in shallow and warm water
at the end of the dry season with peak from February to April. The use of molluscicides
was tested in Laos but it was reported ineffective.
The transmission dynamics of S. mekongi infections in Cambodia, Laos and
Thailand was shown. The most important risk factor is constituted by contacts with the
river’s water such as children playing in the river, women washing and fishing activities.
It is very difficult to modify this risk behavior. During the high transmission season the
temperature is the highest in the year, so people go very often to have ‘refreshing’ baths
in the river. It is also easy to catch edible aquatic snail in the dry season. The
18
transmission period coincides with the most suitable time for fishing. There are no
latrine or washing facilities in endemic villages.
Photographs of the snail habitats and severe cases of schistosomiasis mekongi
were shown. Photographs of health education, ultrasonographic examination, application
of rapid-ELISA for field survey on schistosomiasis mekongi and comparison of US
images of liver between schistosomiasis mekongi and schistosomiasis japonica patients
were shown.
Graphs showing progressive change of SMP-ELISA values with S. mekongi egg
antigen for schistosomiasis in Cambodia (1998-2003) were presented. Photographs of
epidemiological survey in children were shown where stool examination and praziquantel
treatment were conducted were shown.
The history of Schistosomiasis-Helminth Control in Cambodia is seen in the
following.
• 1995: Pilot schistosomiasis control project started at schools and communities
• 1997: National helminth control programme established, and STH control
integrated.
• 1998: A pilot project of school based deworming programme started in Mean
Chey district
• 1998: STH control covered 12 provinces across the country
• 2000: World Health Assembly Resolution WHA50.29 (LF)
• 2001: World Health Assembly Resolution WHA54.19 (STH and Schisto)
• 2003: National Task force, Policy and Guidelines formulated and approved
• 2003: School based deworming programme scaled up to the whole country
The three target areas of the National Helminth Control Program in Cambodia are
STH, schistosomiasis and lymphatic filariasis. The schistosomiasis control strategy in
Cambodia included initial epidemiological assessment followed by universal treatment
campaign of praziquantel (40mg/kg/BW) with health education campaign in a target
population 80,000 people in 56 villages in 2 districts in Kratie and 58 villages in 5
districts in Stung Treng. This is followed by surveillance and monitoring and case
management. Campaign coverage ranged from 65 to 75%. Parasitological and morbidity
indicators were monitored in 4 sentinel villages.
For the status of schistosomiasis in Cambodia, MDA is given every year to
approximately 80,000 individuals in the two endemic provinces of Kratie and Stung
Treng (Montresor 2006). Before the Ministry of Health began universal chemotherapy
with praziquantel in 1994, severe morbidity and mortality in Kratie and Stung Treng were
common (Sinoun et al. 2007). Five years after this intervention was instituted, prevalence
decreased from an average of 72% to less than 10% in four sentinel villages (Urbani and
Palmer 2001).
Decrease in hepatomegaly in children in four endemic areas in Kratie was shown. The
impact of control in four sentinel villages in Kratie was presented. Throughout the 8
19
years that the programme continued, coverage reached between 62% and 82% of the
population. Infection declined significantly as a result of the intervention, with 3 reported
cases total in 2005 and no reports of severe morbidity (Sinuon et al. 2007) No new cases
have been reported since 2006 (Montresor 2006). The Ministry of Health is planning to
increase the interval between campaigns to two years.
The future plan of schistosomiasis control in Cambodia includes elimination of
schistosomiasis, achieve the morbidity < 1 % (Kato-Katz), no new severe case, joint
activities undertaken in Cambodia and Laos (Border disease control), integrated control
project with STH and LF and animal reservoir study to be undertaken.
Photographs of school based deworming programme in Cambodia were shown.
Soil-transmitted helminths commonly called intestinal worms, are the most common
infections worldwide, affecting more than 2000 million people. Causal agent is any of
the following worms: Ascaris lumbricoides, Trichuris trichiura and the hookworms. The
greatest numbers of STH infections occur in sub-Saharan Africa, the Americas, China
and east Asia. Infection is caused by ingestion of eggs from contaminated soil (A.
lumbricoides and T. trichiura) or by active penetration of the skin by larvae in the soil
(hookworms). 60% of STH cases are children and 40% adults.
STHs produce a wide range of symptoms including intestinal manifestations
(diarrhoea, abdominal pain), general malaise and weakness that may affect working and
learning capacities and impair physical growth. Hookworms cause chronic intestinal
blood loss that results in anaemia.
The recommended intervention strategy and aim in STH control includes targeted
administration of albendazole, mebendazole, levamisole or pyrantel. The frequency of
intervention is determined by the levels of prevalence and intensity of infection among
school-age children.The aim is morbidity control: periodic treatment of at-risk
populations will reduce the intensity of infection & protect infected individuals from
morbidity due to STH.
The strategy for STH control is to treat once or twice per year the eligible
population which includes preschool and school-age children, women of childbearing age
(including pregnant women in the 2nd and 3rd trimesters and lactating women) and
adults at high risk in certain occupations (e.g. tea-pickers and miners).
In the school based deworming programme, prevalence survey are conducted at
primary schools. There is training of school teachers and health center staff on mass drug
administration and health education. MDA is done at primary schools by teachers.
Outreach services for pre school children are done by health center staff. Integration of
MDA in other on-going public health activity is done. Lastly partnerships (Partnership
for Parasite Control) are extended further. The school deworming program structure was
shown.
20
For the training of school teachers and health center staff, 1299 school directors
and 1138 health center staff were trained and 5825 schools received school health kits.
The school kit included five teacher reference books, ten story books, two flipcharts, ten
posters, two games, medendazole 10,000 tablets and report forms. One kit for 500
children $41.5 including drugs. The impact of mass drug administration for STH control
at primary schools in Meanchey district was shown.
The goals set as part of The World Health Assembly Resolution, 2001are as
follows.
1. To regularly teat at least 75% of all school-age children at risk of
schistosomiasis and STH infections
2. To ensure that people have access to deworming drugs at their local health
facilities
3. To provide regular treatment to other high risk groups for example fishermen
who are at particular risk of schistosomiasis and miners who are especially
prone to STH infections.
According to the World Health Assembly Resolution WHA54.19 (22 May 2001),
the global target is to regularly treat at least 75% of all school-aged children at risk of
illness from schistosomiasis and soil transmitted helminths.
Cambodia’s success story can be told in the following. In 1999, > 70% of
Cambodian children were infected with intestinal worms. In 2003, Cambodia treated 2,
186,483 children with worms. In 2004, 2,344,564 out of 2.8 million primary school
children educated & treated (83.7% of primary school children). In July 2004, Cambodia
became first country to reach the 2010 Global Target and that too much ahead of time.
Today, 100% of the school-age population in the country is protected. In 2005, Cambodia
succeeded also in process eliminating schistosomiasis.
Cambodia’s success in achieving the Global Target ahead of time can be traced to
the following. A child needs only one tablet of mebendazole or albendazole for STH.
Praziquantel for schistosomiasis requires an average of 2 tablets per year. The cost of
treatment with either mebendazole or albendazole is only US$ 0.02 while treatment with
praziquantel costs US$ 0.20. However, setting up a comprehensive control programme is
a financial challenge for many developing countries including Cambodia. The strong
political commitment of the Government of Cambodia should also be sustained. Strong
financial support provided by international partners and donors has made the deworming
programme a remarkable success story.
The factors that contributed to Cambodia’s success story included the following.
The deworming programme is carried out by trained teachers through the school system.
Two rounds of treatment take place every year in all 24 provinces. Mebendazole is used –
thus the dose is simply one tablet per child in each round. A school kit is provided for
educating children. Keeping future generations healthy is a goal of the deworming
program. The deworming programme focuses on the distribution of drugs and education
through the school system to benefit future generations of children.
21
In summary the factors contributing to Cambodia’s success are efficient
programme management-working through schools, government’s strong political
commitment and training.
In ensuring the integration of schistosomiasis and STH, where both parasites are a
public health problem, control programmes must address both at the same time.
Interministerial collaboration is essential for successful deworming programmes. There is
a need to work with partners in the national worm control programme. The partners for
helminth control in Cambodia include National Center for Parasitology, Entomology
and Malaria Control (CNM), MoH ; School Health Department, MoEYS; Sasakawa
Memorial Health Foundation; Dokkyo University and Tsukuba University, Japan;
Embassy of Japan Cambodia; JICA – ACIPAC; NGOs: MSF, PFD, GTZ and World
Health Organization / TDR/UNICEF.
Deworming in Cambodian schools is promoted by the production and distribution
of a school kit. The school kit is composed of deworming pills; health education posters
and pamphlets for teachers and games and attractive pictures for children with simple
messages. All this has been possible at a cost of US$ 0.07 per child treated.
“Cambodia's control programme is a national triumph as well as an exemplary
model for other countries.” In the WHO (2007). Neglected Tropical Diseases; hidden
success, emerging opportunities, "Cambodia's experience provides hard evidence that it
is completely within the realm of possibility to protect the vast majority of children
against parasites. Cambodia has done it, and so can other countries“ - Dr. Lorenzo Savioli,
WHO Coordinator of Parasitic Diseases Control.
39-4
The comparison of ultrasonographic, serologic and coprologic examination of
schistosomiasis japonica patients in Sorsogon, the Philippines
Y Chigusa1, T Inoue2, LR Leonardo3, NL Arevalo4,
RG Lim, LM Agsolid4, M Kirinoki1, T Agatsuma5
1
Center for Tropical Medicine and Parasitology, Dokkyo Medical University,
Japan,
2
Faculty of Nursing, Fukuyama Heisei University, Japan,
3
Department of Parasitology, College of Public Health,
University of the Philippines Manila, the Philippines,
4
Provincial Health Team, Sorsogon, the Philippines,
5
Department of Environmental Health Sciences, Kochi Medical School, Japan
This schistosomiasis survey using ultrasonographic, serologic (ELISA) and
coprologic examinations (Kato-Katz thick smear) was conducted in Sorsogon, the
22
Philippines in August 2005, January 2006 and January 2007. 1390 participants coming
from 22 schistosomiasis endemic barangays were involved. The study sites were in the
municipalities of Irosin and Juban, province of Sorsogon, the Philippines.
1)
2)
3)
4)
The subjects, classified by sex and age were divided into four groups namely
19 years old and younger
20-39 years old
40-59 years old
60 years old and older.
The examinations done were Kato-Katz stool examination, immunological
examination (ELISA) and ultrasonograhic examination. ELISA results were categorized
into positive for schistosomiasis and negative for the disease. For Kato-Katz thick smear
examination subjects were classified as positive if Schistosoma japonicum eggs were
detected in the stool and negative if eggs were not found. Those who underwent
ultrasonography were classified into NW group (or those whose results show network
echogenic pattern) and non-NW group.
Liver US images due to schistosomiasis japonica were shown. Number of subjects
examined in Sorsogon, the Philippines were classified according to sex and age groups.
The Kato-Katz positivity rate by sex and by age groups was presented. Percentages of
subjects who received no PZQ treatment in previous 15 years were given.
Results shown in graphs were ELISA positivity rate by age group and by sex and
comparison of Kato-Katz and ELISA positivity rate. The study proved that Kato-Katz
stool examination is very simple, cheap and applicable in remote areas but its sensitivity
is not high. Results of the ultrasound positivity rate, ELISA positivity rate by US Type
and comparison of ultrasound and ELISA results were presented. Ultrasound images
showed that the percentage of subjects with network echogenic pattern increases with age
in both male and female. The percentage among females is also less than half that of
males.
Results show the big disparities in the proportion of subjects diagnosed with the
disease using ELISA and Kato-Katz. ELISA is able to diagnose a few to more than ten
times the capacity of Kato-Katz. But between ELISA and ultrasonography, the disparity
is not that big. It is clear from this study that coprological examinations like Kato-Katz
may not be enough to show the real prevalence rate of schistosomiasis in the area. This
has to be supplemented by more sensitive tests like ELISA. Ultrasonography may not be
sensitive enough to detect the early damage due to schistosomiasis.
39-5
Modeling the dynamics and control of transmissions of Schistosoma japonicum and
S. mekongi in Southeast Asia
23
Ishikawa H1, Hisakane N1,2, Ohmae H3, Kirinoki M4, Chigusa Y4, Pangilinan R5,
Redulla A5, Sinuon M6, Socheat D6, Matsuda H7
1
Dept. of Human Ecology, Graduate School of Environ. Sci., Okayama Univ.,
2
Japan, Hitachi Co., Ltd., Japan, 3Dept. of Parasitol., National Inst. of Infect. Diseases,
Japan, 4Center for Trop. Med. and Parasitol., Dokkyo Medical Univ. School of Med.,
Japan, 5Schistosomiasis Control Team, Trinidad, Bohol, Philippines, 6National Center
for Parasitol., Entomol. & Malaria Control, Ministry of Health, Cambodia, 7Inst. of
International Education and Research, Dokkyo Medical Univ., Japan
Schistosoma japonicum in Bohol, the Philippines is characterized by seasonal
variation of snail density and involvement of animal reservoir hosts. A transmission
model scheme is produced based on control strategies and simulation results.
Schistosoma mekongi is found in Kratie, Cambodia. Snail population dynamics on PSS
hypothesis is proposed. Animal reservoir hosts are also involved. A transmission model
scheme is also proposed based on control strategies and simulation results.
The study area in the Philippines is in northern Bohol in Talibon and Trinidad.
From average rainfall for the past 30 years, the dry season falls on January to May while
the rainy season is from June to December. The seasonal variation in the density of snails
shedding cercariae was proposed as derived from a model. The prevalence of S.
japonicum in animal reservoir hosts in Bohol was shown. A model scheme involving
humans, snails and reservoir hosts was shown.
Control strategies against S. japonicum in Bohol consist of human control
involving detection of infected individuals (stool examination) and chemotherapeutic
treatment (praziquantel) and snail control involving environmental change such as land
reclamation and using molluscicide. A comparison between the prevalence of S.
japonicum in humans from the model and the observed data (Sto Tomas) was shown. A
comparison between the changes of infection of S. japonicum in snails derived from the
model and the observed data (Sto Tomas) was presented. Prevalence in human population
and density of infected snails (Sto Tomas) with control condition for four years and for 8
years was shown.
The study constructed a model of S. japonicum transmission to describe the
prevalence quantitatively. The simulation showed that there is little probability of
resurgence of an epidemic for several years with a high coverage of selected mass
treatment accompanied by snail control.
In Cambodia the study area was in the Mekong Basin in the
Kratie province. The monthly average rainfall levels and Mekong River water levels
were shown.
The snail population dynamics on Post-Spate Survival hypothesis was shown.
During the high water period, there is considerable mortality and copulation but delay in
24
laying eggs. During the low water period, new born snails are appearing, eggs are
hatching, old snails lay eggs and old snails die.
A model scheme involving humans in 8 age categories, newborn and old snails
and reservoir hosts particularly dogs was shown. Only human control is implemented
since snail control has been found ineffective in the Mekong River Basin. Human control
includes universal treatment and targeted treatment which involves detection of infected
individuals (stool examination) and chemotherapeutic treatment (praziquantel). Health
intervention includes health education and provision of latrines.
Results shown included transition of age-specific prevalence of S. mekongi;
variations of the prevalence in humans with 3 control measures and variations of the
prevalence in humans with 2 control measures.
The study constructed a mathematical model for S. mekongi transmission in
consideration of the fluctuation of water level in the Mekong River and dynamics of the
intermediate snail host population. The simulations predicted that the suppression of
schistosomiasis would be possible in Cambodia by maintaining control strategies for
humans such as yearly targeted mass treatment with a high coverage rate.
39-6
An Update of Schistosoma mekongi and Opisthorchiasis situation in Lao PDR
Dr Samlane Phompida,
Dr Rattanaxay Phetsouvanh
CMPE, Lao PDR
Lao PDR has 5.6 million people with 3 major ethnic groups. Helminth control
activities include 10 yr control of schistosomiasis and opisthorchiasis 1989-1999;
nationwide survey on helminth infections 2000-2002; opisthorchiasis control programme
2002-2004 and natiowide deworming 2005-2009.
For the 10-year control of schistosomiasis, the first 6 years of the program were
supported by the WHO while the last 4 years by German Pharma Health Fund. The
control program included six rounds of mass treatment and health education campaigns.
The prevalence of S. mekongi in Khong district reduced dramatically from > 50%
to
< 2% (survey 1999). Opisthorchiasis was reduced to approximately 20%.
What happened after 1999? In 2003, stool survey was done in 64 villages in
Khong & 10 in Mounlapamok districts (7,975 examined by Kato-Katz). Prevalence of
schistosomiasis mekongi was 11% (0-47%) and 1% (0-8%) in the two districts
respectively. Approximately 30% of infections were of medium intensity & 15% were of
heavy intensity. Opistorchis prevalence was 50% (0-100%) in Khong and 47% (0-82%)
in Mounlapamok.
25
In 2004, Prof. Makiya and his team surveyed 7 villages. The prevalence of
schistosomiasis mekongi was found to be 17% (448 examined; 0-72%). Nylon mesh
filtration was used. Mass treatment in 74 villages was done in Khong and 22,271 people
were treated in November. In 2006, Prof. Makiya and his team surveyed 7 more villages.
Prevalence of schistosomaisis was palced at 17% and opisthorchiasis viverrini at 5 %.
448 examined using nylon mesh filtration. Prof. Matsuda and his team did another stool
survey where schistosomiasis mekongi was found to be 36% and opisthorchiasis viverrini
at 28%. 183 were xamined by formalin detergent method. 242 were examined by
ELISA yielding a prevalence rate of 85%. In 2008, MDA was conducted in Khong and
Mounlapamok districts with a coverage of 80%. This was funded by CDC-ADB.
A graph showing Opisthorchis viverrini infections among school children by
province, 2000-2002 was presented. Experiences of opisthorchiasis control included a10year opisthorchiasis and schistosomiasis control project in Champassak province (pop.
600,000) which resulted in the reduction of O. viverrini from > 70% to 19%. A 3-year
community based pilot project was implemented in 2 districts of Vientiane province (pop.
69,000).
A 3-year community based control programme for opisthorchiasis control in
Vientiane Province included training workshops, mass drug dministration (praziquantel40 mg/kg) once per year, IEC campaign with posters, booklets and comic books and
baseline and cross sectional stool surveys in 4 villages. A summary of treatments and
surveys was shown. Examples of IEC materials were presented. Intemsity of opisthorchis
infections in four monitoring villages was shown.
Schistosomiasis and opistorchiasis control in Southern part of Laos was very
successful with a significant reduction of cases during 1989-1999. After 1999 and
onwards there has been a high re-insurgence of schistosomiasis and opisthorchiasis and
will continue to increase unless control is re-initiated again.
Recommendations include long term support for sustainable control;
strengthening of provincial and district resources for decentralized control; raising the
awareness and special attention in high risk areas; integrated schistosomiasis and
opisthorchiasis control and integrated health education with water and sanitation.
Future plans include ADB / WHO project, the Greater Mekong BasinCommunicable Disease Control for strengthening national response for neglected tropical
diseases (opistorchiasis, schistosomiasis, LF, dengue) and integrated control with STHnational school based de-worming. With support from the Sasakawa Memorial Health
Foundation, a joint activity for schistosomiasis control will be implemented in Cambodia
and Lao PDR.
26
New Tools for Treatment and Prophylaxis
Ohta N1, Taniguchi T1, Kumagai T1, Shimogawara R1, Kim HS2 and Wataya Y2 of
the Tokyo Medical and Dental University, Tokyo and 2Okayama University, Okayama,
Japan.
1
Therapeutic effects of a synthesized compound on schistosomiasis mansoni: two
different effects on worm killing and anti-fecundity in murine experimental infection.
Schistosomiasis is a typical Neglected Tropical Disease with big numbers of
people who are infected and/or at risk and big DALYs. >200 million people are infected
and DALYs exceed 5 million. It used to be a disease of poor prognosis but with now
Praziquantel is used for safe deworming. Prophylaxis is difficult under the insufficient
infrastructure especially with the question of availability of safe water. Social
development often leads to expansion of endemic areas.
To the question why new drugs are needed. The answers are vaccine development
is far from the practical use. Praziquantel is the only one and the last line drug for
schistosomiasis. Resistant parasite strains to praziquantel remain a question.
Arthemisinin-analogs are the newly found anti-schistosomal medicine, however, they are
expensive for mass treatment.
The future strategies of case management are influenced by new drugs available
for schistosomiasis; mechanisms of the drug efficacy and stable supply of drugs at
inexpensive cost.
There is a paper entitled “Therapeutic effects of a synthesized compound on
schistosomiasis mansoni: two different effects on worm killing and anti-fecundity in
murine experimental infection” by Ohta N1, Taniguchi T1, Kumagai T1, Shimogawara
R1, Kim HS2 and Wataya Y2 of the 1Tokyo Medical and Dental University, Tokyo and
2
Okayama University, Okayama, Japan.
A historical view of anti-schistosome drugs in Japan was presented. Traditional
local medicine has been available in the 19th century. New therapeutics were being
developed in the early 20th century. Local newspaper reported about successful effects
of Stibnal (Sodium antimonyl tartate (C4H4NaO-Sb)) for schistosomiasis in 1922.
Different targets of the drugs praziquantel, artemisinin analogs and oxadiazole
were shown. Artemisinin-delivatives as anti-schistosome drugs are promising. There is
low toxicity to mammals. They have strong killing activity to young adult stages,
possibly due to the endoperoxide component. They are effective at 300mg/kg in mice and
less than 10mg/kg in humans. They have weak but significant killing activity to mature
stages of the parasite. However, there are no apparent effects on sexual maturation of
female parasites. They are still expensive and of limited supply. The drug usage in
malaria-endemic areas is still a problem.
The structure of praziquantel, artesunate and N-89, a synthetic circular peroxide
compound was presented. N-89 is a synthetic circular peroxide compound (1,2,6,7Teraoxaspiro[7,11] nonadecane) with MW = 273. It is water insoluble and non-toxic to
mice at 1,600 mg/kg po. It has selective toxicity to the malaria parasite and mass
production is inexpensive. The procedure for screening of N-89 for anti-schistosome
27
effects in vivo was shown. The two distinct effects of N-89 namely reduction in worm
burden and reduction in egg number were shown. The possibilities drawn this study are
that N-89 seems to have schistosomicidal effects in the early developmental stage, but
less than that of artesunate in the protocol tested and that N-89 seems to have antifecundity without schistosomicidal effects.
The study showed that for schistosomicidal effects, the optimal time point for
treatment using N-89 300mg/kg po is on the 14-15th day post infection or two weeks post
infection. The results of the study showed that N-89 seems to have strong killing effects
when mice were treated at the early phase of infection with the maximum effect observed
at 2 weeks after infection. However, there are no killing effects at the stage migrating in
the connective tissue. The optimal time point for anti-fecundity is 5-6 post-infection.
Week 5 treatment prevented pathological lesions. Liver weight in N-89 treated BALB/ｃ
mice was compared with mice treated with olive oil and untreated mice.
Results of the study showed that N-89 seems to have strong antifecundity effects
when mice were treated at their mid phase of infection with the maximum effect was
observed at 5-6 weeks after infection. The two different active phases of N-89 were
shown to be parasite killing at two weeks post-infection and effects on egg production at
5 weeks post-infection. Effects of in vitro treatment of N-89 on lung-stage larvae and on
3-week young adults were shown.
The mechanisms of the two distinct effects of N-89 can be better understood by
looking into the ultrastructure of parasites after the drug treatment and doing proteome
analysis for altered structure of the parasites. Damages of the parasite tegument by
artesunate in vivo. Damages of the parasite tegument by artesunate in vivo were shown.
These include damaged sucker, tubercular damage and focal swelling. The ultrastructure
of parasite surface after N-89 treatment was presented. The procedure for profile analysis
in proteome: in vitro treatment was shown. 2-D PAGE patterns of S. mansoni with N-89
treatment were presented.
In summary, N-89 is a probable new antischistosomal drug with practical use. It
has a different efficacy mechanisms from praziquantel and also possibly show different
effects from artemisinin-analogs. Mechanisms for the drug efficacy are not yet
uncovered, however, tegumental damage at young adult stage and sexual maturation of
adult female warms might be the targets. N-89 could be a new anti-schistosome drug with
unique efficacy: anti-disease and transmission block?
Other questions that have to be answered are should the female worm be the focus
for drug efficacy? Should there be testing of other chemically modified delivatives of N89? Should more reliable in vitro treatment and assay be established? Should there be
testing in domestic animals and humans in the future?
Identification of New Drug Leads for the Control of Schistosomiasis
David L. Williams
Immunology/Microbiology
Rush University Medical Center
Department of Biological Sciences
Illinois State University
28
Schistosomiasis (Bilharzia or snail fever) infects 207,000,000 people in the world.
There are an estimated 280,000 deaths/year. It is a major cause of underreported
morbidity. It is endemic in 75 countries and almost 800 million people are at risk.
Chemotherapy is an important component of schistosomiasis control. Praziquantel is
single widely used drug. Tens of millions of people are treated annually however rapid
reinfection occurs after treatment. Resistance possible and there is still a question of
resistance at present. There is an urgent need for new antischistosomal drugs.
The study on drug development targeting thiol-based redox enzymes includes the
following. Redox biology includes thioredoxin and glutathione systems and redox
biology of Schistosoma Validation of redox enzymes as an essential proteins consists of
biochemical validation and genetic validation. Lead identification consists of disulfide
oxidoreductase enzyme-targeted leads, structure-activity relationship for leads and
mechanism of action of leads.
In the identification of new schistosome drug target, antioxidant enzymes and
redox balance are drug targets. Experimental schistosomiasis vaccines target redox
proteins such as glutathione S-transferase (Capron et al. Trends Parasitol. (2005)) and
superoxide dismutase/glutathione peroxidase (Shalaby et al. Vaccine (2003); Cook et al.
Infect. Immun. (2004)). Anti-schistosome drugs may target redox balance. Oltipraz
lowers GSH levels and inhibits glutathione reductase activity (Frappier et al Biochem.
Pharmacol. (1988) 37;2864; Mkoji et al Biochem. Pharmacol. (1989) 38;4307 and
Moreau et al Biochem. Pharmacol. (1990) 40;1299).
The basis for antioxidant enzymes and redox balance as drug targets was shown.
The work on the isolation of S. mansoni thioredoxin glutathione reductase (TGR) could
not purify a GR activity from worms and could not identify ESTs with similarity GR
proteins. It also found ESTs with similarity to TrxR and identified full-length clones with
110 amino acid N-terminal extension. Other results selenocysteine encoded by TGA
(termination codon) and thioredoxin glutathione reductase in mammals. Recombinant
protein/antibodies were also produced. It was proposed that one protein provides both
TrxR and GR activity in worms.
Results of immunoprecitation of TGR – GR, TrxR and Grx activities were shown.
It is hypothesized that TGR provides both TrxR and GR activities in S. mansoni. Gold
compounds selectively inhibit selenocysteine proteins (TrxR/TGR) and not cysteine
proteins (GR). For GR activity: TGR + GR are present. Biphasic inhibition of TrxR
activity was shown. For TrxR and GR activities, one enzyme is present. The same
inhibition curve for TrxR and GR was noted. The mono-phasic curve for TrxR inhibition
was shown. The distinct biochemical differences between schistosome and human
flavoenzyme oxidoreductases enzymes were shown.
Peroxiredoxins in S. mansoni are most important in H2O2 reduction in
schistosomes. There are isoforms namely cytoplasmic/secreted, cytoplasmic and
mitochondrial forms. They are 2-Cys containing enzymes. They use Trx and GSH
(human enzymes only use Trx). Humans have six peroxiredoxins. The chemical basis for
antioxidant enzymes and redox balance as drug targets was shown. Likely all trematodes
and cestodes have similar coupled redox pathways.
Validation of TGR as an essential protein is by biochemical validation as shown
by the following works: Auranofin: organic gold compound, rheumatoid arthritis by Kean
29
et al. Br J Rheumatol (1997); Auranofin inhibit Trx reductase >> GPx & GSH Reductase
by Gromer et al. JBC (1998) and Auranofin inhibits native and recombinant TGR, IC50 =
10 nM by Alger & Williams MBP (2002). Biochemical validation of TGR was further
shown by treatment of adult worms with 10 μM auranofin inhibiting TGR activity >90%
in 6 hr; ratio of GSH:GSSG in worms reduced after auranofin treatment and worm death
in ~8 hr. Auranofin treatment (6 mg/kg twice daily, 8 days) in mice experimentally
infected with S. mansoni resulted in total worm burden reduction.
Oltipraz and potassium antimonial tartrate also inhibit TGR. Oltipraz is a
clinically relevant drug with IC50 = ~20 µM. Potassium antimonial tartrate is the first
synthetic drug used for schistosomiasis treatment (Christopherson, 1917) with IC50 = ~5
nM. Phosphofructokinase has IC50 >1000 x higher.
Genetic validation of TGR as an essential protein was shown. Genetic validation
of Prx as essential proteins was shown. Results of silencing with Prx1 dsRNA leading to
reduced Prx transcripts, reduced Prx proteins, reduced H2O2 reduction activity by 85%
and worm death which is accelerated by oxidative stress and inhibited in anaerobic
culture were shown.
The work on the identification of lead compounds that inhibit TGR/Prx showed
that there are active recombinant TGR and Prx proteins which are essential proteins and
biochemically distinct from host orthologs. There is a robust inexpensive assay for HTS.
For lead identification, disulfide oxidoreductase enzyme-targeted leads and highthroughput screen small compound libraries.
The high-throughput screen for redox enzyme inhibitors has been shown by NIH
Roadmap Initiative – Molecular Libraries Screening Centers Network [Austin et al
Science (2004) 306;1138] and NIH Chemical Genomics Center (NCGC). The reaction
can be followed by decrease in NADPH fluorescence [Inglese et al, PNAS (2006)].
Study of high-throughput screen for redox enzyme inhibitors showed the
following results: ~70,000 compounds, 7 concentrations, time course (>500,000 data
points); 100 compounds with IC50 < 40 µM - ‘molecular probes’; 9 mercurials; 11 heavy
metal-containing compounds (Sb, As, Ag, Cu, Au); 9 compounds from NIEHS; 71 nonheavy metal-containing compounds and ≥ 6 different compound classes. The highthroughput screen for redox enzyme inhibitors was shown.
The activity of oxadiazole 2-oxide series against cultured adult worms was
shown. Nitric oxide donation by oxadiazole 2-oxides was shown with the results of
incubation with TGR, TGR + NADPH, or 5 mm cysteine. Protection from NO toxicity by
2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (carboxy-PTIO) was
also shown.
The activity of furoxan against cultured parasites was presented. The activity of
furoxan in infected mice @ 10 mg/kg, 5 daily doses ip was shown. Reduction in worm
burden with treatment of infected mice with furoxan was shown. Photomicrographs of
adult S. mansoni worms recovered from infected mice treated with furoxan and control
infected mice were shown. Worms recovered (males and females) from treatment group
are stunted relative to worms recovered from untreated infected mice. Results of
treatment of infected mice with furoxan showed reduced egg-induced pathology. In a
graph, the effectiveness of furoxan, praziquantel and artemether against S. mansoni
infections in mice was shown.
30
The criteria established by the World Health Organization for potential lead
compounds for schistosomiasis [Nwaka & Hudson Nat. Rev. Drug Discov. 5, 941-955
(2006)] include the following: HIT: 100% inhibition of motility of adult parasites at 5
µg/ml and LEAD: 80% reduction in worm burdens when administered in 10% DMSO
in 5 injections at 100 mg/kg. Furoxan shows the following features: 100% inhibition of
motility of adult parasites at 0.38 µg/ml and > 88% reduction in worm burdens when
administered in 10% DMSO in 5 injections at 10mg/kg.
With graphs, the following results were presented. Dose dependency in the
treatment of infected mice with furoxan; activity of oxadiazole analogues against S.
mansoni TGR and ex vivo adult worms; activity of oxadiazole analogues against S.
mansoni ex vivo adult worms and TGR, human GR and rat TrxR; activity of oxadiazole
analogs against S. mansoni TGR – thiophene derivatives; and preliminary cytotoxicity of
oxadiazole analogs. The steps showing the mechanism of action of oxadiazoles. The
structure of truncated TGR protein was presented.
In summary, schistosomes redox enzymes (TGR & Prx) are distinct from host
enzymes. TGR and Prx are essential parasite proteins. TGR and Prx are validated drug
targets and identified potent leads for schistosomiasis treatment. Future plans include
investigating the mechanism of catalysis of TGR and structure of TGR and lead
compound development such as oxadiazole 2-oxides ---- furoxan lead; naphthoquinones
and Mannich bases and phosphinic amides and phosphoramidites.
Molecular characterization of Schistosoma japonicum tegument protein tetraspanin2: Sequence variation and possible implications for immune evasion
Pengfei Cai, Lingyi Bu, Heng Wang
Laboratory of Parasitology, Chinese Academy of Medical Science
Schistosomiasis is the most serious parasite disease in China. 0.8 million people
suffer from the disease and more than 65 million people in China are at risk.
Data showing that tetraspanins (TSPs) of Schistosoma mansoni are protective
antigens are presented. The structural features of tetraspanins are shown. The procedure
for cloning of Sj-tsp-2 ORF is presented. Results shown include variation of Sj-tsp-2 into
seven subclasses and Sj-tsp-2 variation at the amino acid level. The 3D structure of SjTSP-2e shows the variable region exposed at the surface of the molecule. Results
shown include transcription profiles of Sj-tsp-2 subclasses in individual adult worms
were presented. Results of cloning of large extracellular loop of Sj-tsp-2 and purification
of recombinant proteins; detection of transcription levels and expression of Sj-tsp-2 at
various developmental stages; localization of Sj-TSP-2 proteins in schistosomula and
adult worms and eEvaluation of protective immunity.
In summary, extensive variation and different expression profile in individual
worms implied that this tegumental molecule may be involved in immune evasion. The
high polymorphism of this molecule must affect its potential as a vaccine candidate. The
difference between Sm-TSP-2 and Sj-TSP-2 suggests that the Schistosoma species, which
live under different environmental pressures, may adopt different survival strategies,
including immune evasion strategies.
31
Clinical Immunology
Human Schistosoma japonicum Infection in Pregnancy (a pilot study)
Research Institute for Tropical Medicine (RITM), Philippines
Center for International Health Research (CIHR)/RIH, USA
The health of a woman affects pregnancy and birth outcomes. In less developed
countries like the Philippines, pregnancy is complicated by inadequate nutrition, poor
environmental conditions and exposure to higher rates of infectious diseases contribute
significantly to LBWs, birthweight as a primary measure of birth outcomes. Diseases
and other problems can often complicate or become more severe during pregnancy.
Malaria with anemia for example worsens during pregnancy and around 10,000 of these
women and 200,000 of their infant die as a result of malaria infection, and severe anemia
due to malaria is contributing to half of these deaths.
Schistosomiasis remains a significant cause of morbidity, but very few data is
available that address schistosomiasis during pregnancy. Recently the burden of disease
due to schistosomiasis was reassessed which showed 4-30 times greater than the
estimates of the 1996 Global project on disease burden. And these estimates do not
include any impact of schistosomiasis on pregnancy. PZQ was widely used since the
early 80s, but was never studied in pregnant or lactating women and thereby classified as
Class B category. Class B drugs are presumed safe based on animals studies, but lack
safety data on pregnant women.
Some causes of poor pregnancy outcome include prematurity, IUGR –
Intrauterine growth restriction that includes poor transfer of nutrients across placenta
which may be caused by poor maternal nutrition, anemia, low maternal weight,
primaparity and smoking, pre eclampsia and diseases and infection leading to elaboration
of pro -inflammatory cytokines(TNF-a, IL6 and IFN-g).
The marked elaboration of proinflammatory cytokines (TNFa, IL6, IFNg)
associated with poor pregnancy and birth outcomes have been shown in animal models of
pregnancy, malarial infections and systemic pro-inflammatory diseases such as SLE and
rheumatoid arthritis. These have also seen in local studies in the Philippines on 641 nonpregnant infected individuals which showed that CRP, IL6, TNFa is significantly
increased in serum of infected compared with non-infected individuals. IFNg is highly
increased in heavy infections compared with non-infected. Hypothetical mechanisms of
schistosome associated poor pregnancy outcomes are proposed.
The goals of the pilot study are to determine if S. japonicum infection results in
elevated pro-inflammatory mediators in both the peripheral and the placental
compartments; quantify adverse effect of schistosome infection on pregnant women and
pregnancy outcomes; assess mechanisms of poor pregnancy outcome and set stage for
RCT of PZQ treatment on infected pregnant women.
For the study population, 97 pregnant mothers were enrolled in the study. They
come from S. japonicum endemic rice farming villages in Jaro, Leyte, The Philippines.
The study area has no malaria with low HIV prevalence in the region and with high
prevalence of other helminth infections. The overall health of population is poor.
32
Eligibility for enrollment include age 18 or greater; singleton pregnancy as determined by
midwife; second or third trimester of pregnancy and consent to participate.
The data collected at enrollment included gravidity and parity; gestational age
(based on LMP); height; weight; smoking status and socioeconomic status. Three stools
were collected and examined in duplicate by the Kato-Katz method.
Data collected at 32 wks gestation included peripheral blood sample obtained for
CBC and serum assays; Inflammation analytes (CRP, IL-1, IL-6, IFN-g, TNF-a, TNF-RI,
TNF-RII, IL-4, IL-5, IL-10) and RBC/ Iron metabolism (e.g Ferritin, Erythropoetin,
Soluble Transferrin Receptor).
Data collected at delivery were newborn and placental weight (Tanita scale);
gestational age by modified Dubowitz; wedge sample of placenta for
immunohistochemical assays and placental and cord blood samples for assays as
described for the 32 week maternal blood sample. The preliminary results shown are
unpublished data of the pilot study. The sample size was actually increased to increase
the power in the analysis.
Schistosomiasis is related to 460 gram decreased birth weight in moderate
infections. Schistosomiasis increases pro-inflammation in maternal peripheral blood at 32
weeks. Schistosomiasis increases pro-inflammation in placental blood. Schistosomiasis
increases trophoblast pro-inflammation measured
by immunohistochemistry.
Trophoblast pro-inflammation is associated with decreased birth weight. To determine
the mechanism of proinflammatory secretion in the placental level, the study
hypothesized that parasite eggs could activate trophoblasts via TLR ligation.
To summarize, the study showed that schistosome infection reduced maternal
weight and bio-available iron; increased peripheral and placental pro-inflammation with
adverse pregnancy outcomes like LBW, IUGR and pre-eclampsia.
Another related project entitled “S. japonicum and Pregnancy Outcomes” has the
following objectives: to collect data on safety and toxicity for mother and newborn; to
assess potential benefit of treatment to mother and newborn and to understand
mechanisms of schistosomiasis related pregnancy morbidity.
The study used randomized, double blind, placebo controlled trial with sample
size of 500 infected pregnant mothers with 250 light intensity infections and 250
moderate/Heavy intensity infection. PZQ is given at 14 – 16 weeks gestation at RTR
hospital and followed-up at 10-14 days post treatment at 22, 32 weeks gestation and 2-6
days after delivery. The trial closes out 28 days after delivery. Preliminary results were
presented.
Lastly, definitions of severe adverse events (SAE) and adverse events (AE) were
given. SAE is defined as any adverse event/experience occurring that results in the ff;
death, life threatening, requiring hospitalization or prolonged hospitalization, results in
congenital anomaly/birth defect, persistent or significant disability. AE is any untoward
medical condition, and does not necessarily have causal relationship with the study drug,
solicited (during active surveillance visits) or not solicited, through patient history or
reports.
51-2
33
Effects of schistosome infections on immunodeficiency virus transmission and
progression
W. Evan Secor, Ph.D.
Division of Parasitic Diseases
Centers for Disease Control and Prevention*
Atlanta, GA USA
The reasons for studying coinfections are as follows. Infections in populations
never as “clean” as laboratory conditions. Accurate interpretation of observations may
require taking co-infecting agents into account. The value of epidemiologic associations
is strengthened by demonstration of biologic mechanisms for xxample: co-incidence of
malaria and Burkitt’s lymphoma (decreased EBV immunity w/malaria). There are
implications for immunization and control programs.
For schistosomiasis in Western Kenya, car washers occupationally exposed to
schistosomiasis
(adults) as supported by accurate water contact data. They are a
critical population for understanding pathology and resistance versus susceptibility to
reinfection. However, > 30% of the sexually active population is positive for HIV-1,
thereby likely to affect immune response. This study also address hypothesis of worm
infections contributing to high rates of HIV-1 acquisition/progression to AIDS in subSaharan Africa.
Sub-Saharan Africa constitutes 10% of the world’s population. It also constitutes
65% of world’s population living with HIV/AIDS. The main mode of transmission is
heterosexual sex. There is an apparent discrepancy, although this is not a unified
consensus. There are questions on why there are differences in viral types; differences in
available healthcare; differences in cultural practices and Parasitic disease co-infections.
The rationale for HIV/Schistosomiasis co-infection studies include the following.
Schistosoma spp. and other helminths are strong chronic stimulators of Th2-type
cytokines. In the mouse model there is delayed CD8-mediated viral clearance (esp. in
granulomas) and Th2 immune shift. In vitro studies indicate that HIV demonstrates
increased viral infectivity and replication in cells with Th2 phenotypes. Ex vivo studies
show higher expression of chemokine receptors on CD4 cells from schistosomiasis
patients which reverses with treatment. The question is could treatment of
schistosomiasis and other helminths (with available, cheap, safe drugs) be a cost-effective
public health measure for sub-Saharan Africa?
To answer the question of whether or not schistosomiasis causes higher viral
loads in vivo, case control study should be done but it is ethically difficult. An alternative
is to treat schistosomiasis in co-infected individuals and then compare pre- and postviral loads. Successful treatment is also confirmed by reduction in fecal egg excretion
and circulating schistosome antigen.
To the question does treatment of helminths reduce viral loads in vivo? The
answer is no in the following studies: Kenya: schistosomiasis (Lawn et al., AIDS
14:2437, 2000); Uganda: schistosomiasis and/or intestinal helminths (Brown et al., JID
190:1869, 2004); Zambia: primarily intestinal helminths, some schistosomiasis
(Modjarrad et al., JID 192: 1277, 2005); Uganda: schistosomiasis (Brown et al., JID
191:1648, 2005) and Malawi: intestinal protozoa and worms, some schistosomiasis
34
(Hosseinipour et al., JID 195:1278, 2007). The conclusion may be that perhaps treatment
confers no beneficial effect or could even be harmful to the patients.
Treatment of schistosomiasis is better than no treatment as shown by the study in
Zimbabwe on schistosomiasis published by Kallestrup et al., JID 192:1956, 2005. At 3
months after enrollment, persons randomized into treatment group had significantly less
increase in viral load and significantly less decrease in CD4 cell count than persons who
received delayed treatment.
To answer the question does schistosomiasis exacerbate immunodeficiency virus
infections,
Rhesus monkeys with chronic, undetectable simian/human
immunodeficiency virus (SHIV) infections were exposed to 500 cercariae of S. mansoni
and schistosome egg excretion, plasma levels of SHIV mRNA and cytokine mRNA were
monitored. Results of the experiment were shown.
To determine if schistosomiasis decreases the viral dose necessary to establish
infection, Rhesus monkeys without schistosome infection were exposed to titered
concentrations of SHIV to establish infectious dose in control animals. A second group
was infected with 500 cercariae of S. mansoni, monitored for egg excretion, eosinophilia,
and cytokine levels. At 7 weeks after infection, they were exposed to decreasing
concentrations of SHIV. Results of the study were shown.
The study concluded that Rhesus monkeys with acute schistosomiais have an
AID50 17-fold lower than parasite-free rhesus monkeys. Through week 10 post SHIV
infection, coinfected RM showed higher viral replication than parasite-free RM; higher
number of CD4 & CD8 cells shift to central memory CD4+ cells, and greater number of
viral copies per cell in coinfected RM. Questions raised are whether this is only a
phenomenon of acute infection and bolus of virus versus more physiologic exposure.
Experiments using repeated low dose exposures are ongoing.
The possible mechanisms proposed are as follows. There is effect of local
exposure or a systemic effect. The Intestine is the largest “immune organ. ” There is
Increased translocated bacterial LPS associated with progression of immunodeficiency.
There is exit of eggs through gut wall associated w/increased bacterial translocation
during schistosomiasis (No detectable elevation of serum LPS). There might be
differences in rectal, vaginal and intravenous exposures. There are effects on host
cellularity. HIV replication is associated with activated cells (# of targets, proliferation,
other markers of activation). HIV entry into cells is dependent on chemokine receptors,
viral strain specific.
For S. mansoni infection of rhesus macaques, macaques were infected with 500
cercariae percutaneously. Peripheral blood lymphocytes analyzed by flow cytometry to
determine CD4 T cellsCD4, CD3; proliferationKI-67; activationHLA-DR, CD25
(IL-2R) and chemokine receptorCCR5, CXCR4. Results of the assay were presented.
The following findings were used to answer the question on whether or not mast
cells as reservoirs for HIV-1. Progenitor mast cells (prMCs), but not mature mast cells
express chemokine receptors and are susceptible to infection with HIV-1. The high
affinity IgE receptor, FcεRIα, is expressed at an early developmental stage on all prMCs.
Signaling through FcεRIα enhances CXCR4 expression on prMCs and increases their
susceptibility to HIV-1. prMCs that become infected with HIV, mature and migrate to the
tissue may be HAART-resistant reservoirs of HIV-1. TLR signaling (2, 4, or 9) triggers
HIV-1 replication in mast cells.
35
The IL-4-inducing principle of S. mansoni eggs (IPSE) is a dimeric glycoprotein
of 40kDa, a.k.a alpha-1. It is present in SEA, secreted from subshell area of schistosome
eggs and binds IgE nonspecifically. It triggers IL-4 release from basophils and is IgE
dependent. The signaling may not be dependent on cross-linking. The IPSE/alpha-1 has
two N-glycosylation sites, each occupied in large proportion with core-difucosylated
diantennary glycans carrying ≥1 Lewis X motifs.
The study concluded that increased susceptibility to SHIV during S. mansoni
infect. may result from increased chemokine receptor expression/cell activation. Acute S.
mansoni infection causes an increase in CD4 T cell number, HIV-1 co-receptor
expression and
CD4 T cell activation. Mast cells may be a reservoir for
immunodeficiency virus but a question remains if there is increased mucosal expression
during schistosomiasis. IgE + SEA can increase HIV-1 co-receptor expression and cell
susceptibility. There is Fc receptor dependence. There may be implications for persons
with allergies. There is a question if stimulation of cells result in greater viral production.
If so, what are the intracellular signals?
Other considerations are relevance to humans where schistosome infection is
more persistent; effects of S. haematobium on viral concentration in mucosae (Leutscher
et al., JID 191:1639, 2005; Feldmeier et al., Int. J. STD AIDS 5:368, 1994); effects of
schistosomiasis or other helminths on efficacy of CTL vs. nAb vaccine strategy and
effects of schistosomiasis or other helminths on efficacy of ART.
51-3
Evaluation of a rapid strip testdetecting a parasite antigen (CCA) in urine for
diagnosis of active schistosomiasisin the field
G.J. van Dam, N. Midzi, T. Mduluza, S. Mutero, J.H. Kihara, C.J. de Dood, A.M.
Deelder, A.E. Butterworth
and many collaborators in Zimbabwe, Kenya, Uganda, Senegal etc.
The advantages of field microscopical diagnosis are its high specificity, low costs
and measurement of quantitative data.
Disadvantages include sample definition:
sampling errors; Labour-intensive: workload; the need for trained technicians: sensitivity
related; the need for multiple samples and the subsequent logistic problems and the
professional hazard.
Requirements for field test include easy to perform; fast results; easy to read;
high accuracy; shows active infection; long shelf life; no equipment needed and low
cost (< US$ 3). Examples of filed tests are dipstick and rapid strip test.
Schistosome circulating antigens originate from the parasite gut; can be found in
host circulation; are very stable; can be correlated with relation worm burden; can be
used to produce McAb based ELISA and can be excreted as CCA in urine.The rapid
lateral flow test for detection of CCA in urine was presented. The principle involved in
the test was shown. A variant test using gold label is commercially available. Results of
the evaluation of the specificity and sensitivity of the carbon CCA urine strip were
shown. Results of the field evaluation in a study population in Zimbabwe were
presented.
The trials showed that the specificity of the test is around 95%; sensitivity to S.
mansoni infections from 80-95% and sensitivity in S. haematobium infections showing
36
regional variation, but sometimes up to 80%. It is concluded that the improved urine
CCA strip is a valuable tool for field diagnosis of S. haematobium but particularly of S.
mansoni infections.
51-4
Antibody isotype responses to paramyosin, a vaccine candidate for schistosomiasis,
and their correlations with resistance and fibrosis in patients with Schistosoma
japonicum in Leyte, The Philippines
T. Nara1), K. Iizumi1), H. Ohmae2), O.S. Sy3), S. Tsubota1), Y. Inaba4), A. Tsubouchi1), M.
Tanabe5), S. Kojima6), T. Aoki1)
1)
Dept. of Mol. Cell. Parasitol., Juntendo Univ. Sch. Med., Japan
2)
Dept. of Parasitol., Institute of Infectious Diseases, Japan
3)
Schistosomiasis Res. Hosp., Palo, Leyte, The Philippines
4)
Dept. of Epidemiol. Environ. Health., Juntendo Univ. Sch. Med., Japan
5)
Dept. Trop. Med. Parasitol., Sch. Med., Keio Univ., Japan
6)
Center for Med. Sci., Int. Univ. Health & Welfare, Japan
Schistosomiasis is endemic in 75 tropical and subtropical countries affecting 200
million people. The four species that are pathogenic to man are Schistosoma japonicum,
S. mekongi, S. mansoni and S. haematobium. Pathology is attributed to granuloma
formation. Serious sequelae include fibrosis, portal hypertension and ascites.
The bases for developing vaccines are as follows. There is resistance to
reinfection particularly age-dependent resistance. There is occurrence of acquired
immunity. Immune responses include antibody-dependent cellular cytotoxicity (ADCC)
against worms. There is also CD4+ T-dependent granuloma formation against eggs. For
antibody isotype responses, levels of AWA-specific IgE/IgA increase with age and
correlate positively with resistance to reinfection. Levels of AWA-specific
IgG1/IgG3/IgG4 decrease with age and correlate negatively with resistance to
reinfection.
A list of vaccine candidates for schistosomiasis (WHO, 1998) was presented. The
list includes paramyosin (Sm97/Sj97), Glutathione S-transferase (GST, P28), IrV-5
(Myosin heavy chain), Triose phosphate isomerase (TPI), 23k tegumental antigen
(Sm23/Sj23) and Fatty acid-binding protein (Sm14).
Schistosoma japonicum paramyosin (PM) is a myofibrillar protein localized in the
tegument of cercariae, schistosomula, and adults; secreted from the postacetabular glands
of cercaria and predominantly recognized by the patient sera of schistosomiasis .
Immune responses to S. japonicum PM are found in an epidemiological study that
showed the levels of PM-specific IgA correlated POSITIVELY with age in
schistosomiasis japonica in The Philippines. Studies of a mouse monoclonal IgE, Sj18.1
] showed recognition of the epitope, IRRA, of S. japonicum PM; reduction in the worm
recovery by passive transfer and provocation of
ADCC via eosinophils and
macrophages. The question asked is are antibody isotype responses to PM associated
with age-dependent resistance and pathology in liver fibrosis in schistosomiasis japonica
in The Philippines?
37
The present study was conducted as part of the National Schistosomiasis Control
Program of The Philippines (1981 ~ 1999). Patients enrolled ranged in age from 9 to 69
years (M/F ratio; 92/42), diagnosed by Kato-Katz method and treated with praziquantel
(PZQ). Patient sera were collected with written consent prior to the PZQ treatment. The
antigens used were S. japonicum adult worn antigens (AWA) and a series of the
recombinant S. japonicum PM with full-length: PM (1-866 amino acids) and truncated:
PM1 (1~164), PM2 (157~302), PM3 (297~451), PM4 (447~602), PM5 (597~742), PM6
(734~866).
The markers used for estimation of fibrosis were US (Ultrasonographic) score:
Grade 1~4 (Ohmae et al., 1992a, and serologic markers that include procollagen-IIIpeptide (P-III-P); collagen synthesis; Type-IV collagen (Type-IV); collagen degradation
and total bile acids (TBA). Statistical analyses were done using Student’s t-test: to
evaluate differences of antibody titers between the study and control groups; Pearson’s
correlation coefficient (R): to quantify associations between age, US score, serologic
markers, and antibody titers and multiple regression to compare Antibody titers for
truncated PM and their correlations with age and fibrosis markers. Antibody titers and PIII-P &Type-Ⅳ levels were log-transformed.
Correlations between age and markers of fibrosis in schistosomiasis japonica
patients in Leyte, The Philippines showed accumulation of fibrosis with age and
pathologic progress of fibrosis. Correlations between antibody isotype levels and various
markers were shown. Correlations between antibody isotype levels and various markers
showed that PM-IgA levels correlate positively with age and US score (accumulation of
fibrosis); PM-IgE levels correlate NEGATIVELY with P-III-P (progress of fibrosis);
PM-IgG3 levels correlate positively with age, US score, and P-III-P (accumulation &
progress of fibrosis) and PM-IgG4 levels correlate positively with US score
(accumulation of fibrosis).
Isotype responses to the truncated PM showed that PM6 is hardly recognized.
Correlations between age and antibody isotype levels to the truncated PM showed that
epitopes are associated with age. Correlations between US score and antibody isotype
levels to S. japonicum PM showed that epitopes are associated with accumulation of
fibrosis. Correlations between P-III-P and antibody isotype levels to S. japonicum PM
showed that epitopes are associated with collagen synthesis (progress of fibrosis).
Correlations between Type-IV and antibody isotype levels to S. japonicum PM showed
that no epitope is associated with collagen degradation.
Conclusions from the isotype responses to S. japonicum PM are IgA and IgG3
levels correlated positively with age. IgG3 and IgG4 levels correlated positively with PIII-P level. And lastly IgE levels correlated negatively with P-III-P level. For
development of schistosome vaccines, desired immune responses, including induction of
the anti-PM isotypes, should be provoked to avoid exacerbating the pathology.
38