BMD 4202 – Parasitology Lecture
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PLATYHELMINTHES
Reference: Balatbat, R. (2022,
Platyhelminthes [Video]. Teams.
March
27).
OUTLINE
I. The Blood Flukes
A. Introduction
B. Blood Flukes
C. Schistosoma japonicum
D. Schistosoma mansoni
E. Schistosoma
haematobium
II. The Intestinal Flukes
A. Fasciopsis buski
B. Echinostoma ilocanum
C. Heterophyes
heterophyes
III. The Lung Fluke
A. Paragonimus
westermani
IV. The Liver Flukes
A. Fasciola hepatica
B. Fasciola gigantica
C. Clonorchis sinensis
D. Opisthorchis felineus
E. Opisthorchis viverrine
I. THE BLOOD FLUKES
A. Introduction
Phylum Platyhelminthes General Characteristics
❖ Dorso-ventrally flattened
❖ Leaf-like (Turbellaria - free living and Trematoda - parasitic but
not all monoecious) or ribbon-like (Cestoda - parasitic
tapeworms and all are monoecious)
❖ Bilaterally symmetrical
❖ Mostly parasitic
➔ Members under Trematoda and Cestoda
➔ Members of Turbellaria are free-living
❖ Mostly monoecious
➔ Except for members of the family Schistosomatidae
which are dioecious
Class: Trematoda
❖ Exclusively parasitic
❖ Indirect life-cycle utilizing intermediate host
❖ Larva: ciliated integument
❖ Adult: non-ciliated
❖ Oviparous (Egg-laying)
➔ Eggs, except Schistosomatidae have operculated
eggs
❖ Mostly monoecious except Schistosomatidae
❖ Have two suckers (for attachment): oral and ventral
(acetabulum) suckers (except Heterophyes heterophyes with 3
suckers).
B. Blood Flukes
Six Medically Important Species
❖ Schistosoma haematobium (Endemic in Africa and Middle East)
in asia and latin america; high prevalence in egypt
❖ S. mansoni (Endemic in Africa, certain parts of Asia and South
America)
❖ S. japonicum (Present in East and Southeast Asia)
japonicum is eradicated in Japan, but present in
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China
S. mekongi (Present in China)
S. malayensis (Present in Malaysia)
S. intercalatum (Present in Indonesia)
C. Schistosoma japonicum
Common name: Oriental Blood fluke
Disease: Schistosomiasis
Epidemiology
❖ Most important zoonotic disease in the Philippines since it can
infect hundreds of domesticated and wild animals.
❖ Focus on the intermediate host to eliminate
❖ Non-host specific
❖ Also endemic in China, India and other parts of Southeast Asia;
already eradicated in Japan.
❖ 780 million at risk worldwide
❖ 200 million infected per year
❖ 20 million deaths/year
❖ Distribution in the Philippines: 12 million at risk in 28 provinces
(usually provinces of the south), in 12 regions.
❖ More prevalent in southern areas.
❖ Endemic areas include Oriental Mindoro and provinces in
Visayas and Mindanao.
❖ Imported cases in Manila (from other places)
❖ Misamis oriental is one of the only provinces in Mindanao that
is not included in endemic areas due to high elevation of the
province; hence, no Oncomelania species.
❖ Newly identified endemic area: Cagayan
➔ This is due to the importation of carabaos or water
buffalos from Mindanao.
➔ Noncomplainer quadrasi, an intermediate host, sticks
to the skin/folds of carabaos whenever they swim in
muddy pools.
❖ Reservoir hosts (non-host specific)
➔ Dogs
➔ Cats
➔ Rats
➔ Mice
➔ Cattle
➔ Water buffalos
➔ Swine
➔ Equines
Risk Factors
❖ O. quadrasi in Philippines
❖ Contact with water infested with Oncomelania spp.
➔ Bathing
➔ Washing
➔ Fishing
➔ Farming
❖ No latrine or washing facilities
❖ Defecation in bodies of water
❖ Short supply of safe water
❖ High prevalence among males because most agricultural
workers are males, women are also exposed to parasite due to
bathing and washing/laundry.
❖ Water contact habits (Farming, laundry, etc)
❖ Prevalence is higher in working age groups and in school-aged
children.
❖ Proximity of habitats snail to humans
Morphology
❖ Egg (Diagnostic stage) – non-operculated with lateral knob
❖ Cercaria (Infective stage for the definitive host – forked tail
unlike in others with knob tail. This goes inside the skin due to
release of hyaluronidase acid.
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Habitat: Mesenteric vein draining the small intestine.
S. japnonicum penetrates the skin using hyaluronidase.
Paired adult worms are in constant copulation, Female lives
inside the gynecophoric canal of the male.
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The species and the eggs are highly antigenic. Immune cells
attack these antigens destroying the blood vessel allowing them
to gain access to the duodenum of small intestine. These
specimens can be seen in stool samples.
If the patient defecates directly in the body of water or latrines
with incomplete walls, eggs will be passed and hatched into the
environment releasing the miracidium. The miracidium will look
for a suitable host through penetration to their integument.
Once inside the snail, each miracidium will divide forming the
mother sporocysts. Each mother sporocyst will divide forming
daughter sporocyst. Each daughter sporocyst will divide to form
hundreds of cercariae.
In humans, there is no internal multiplication, cercaria will not
multiply inside the human.
ADULT MORPHOLOGY – Smooth integument; tubercles are
inconspicuous
Male: 12-20 mm
➔ 7 testes in the anterior part
Female: 26 mm
-35,000 eggs/day/worm (most severe
➔ 3,000
manifestation/symptoms)
Life Cycle
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Indirect Life Cycle; needs only one intermediate host
Intermediate host: Oncomelania spp
In the Philippines: Oncomelania quadrasi (Tiny terrestrial
snails)
➔ Snails are found attached to decaying coconut husks,
on the banks of creek, and attached to fallen
branches
In China: Oncomelania hupensis
Intermediate hosts all over Asia:
➔ Oncomelania spp (Freshwater snails)
★ O. quadrasi
★ O. hupensis
➔ China
★ O. nosophora (Japan)
➢ Japan focused on eradicating the
snail host by blocking breeding
grounds
★ O. lindocense (Indonesia)
★ O. formosana (Taiwan)
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Pathology
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Cercarial dermatitis (Swimmer’s Itch)
➔ Each papule is a point of entry for cercaria
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Petechial hemorrhages
Hepatosplenomegaly
➔ Sign of chronic infection
➔ Enlargement of the liver and spleen
➔ Umbilical hernia
➔ Enlargement of abdominal veins
➔ There is hepatic portal tension wherein there is a
blockage of portal veins due to eggs and worms
(highly antigenic) which stimulates calcification and
deposition of collagen around the affected areas.
➔ Signs and symptoms are like Liver cirrhosis.
➔ This condition is irreversible.
➔ Due to hepatic portal tension
Calcification of the liver due to deposition of fibrinogen and
collagen resulting in scar formation. The parasite stimulates
interleukin-13, causing migration of fibroblast in the liver.
Calcification of lungs due to migration of the worm
Diagnosis
❖ Circum-oval Precipitin Test (COPT)
➔ the eggs are subjected to the slide. Add 1 drop of
serum. Incubate for 3 days, waiting for the formation
of blebs (antibodies for eggs)
❖ Ultrasonography
➔ for those that are suffering from hepatosplenomegaly
❖ Kato-Katz – to determine severity
❖ Kato-Thick
❖ Rectal biopsy
➔ for heavily infected
❖ LAMP – Loop-Mediated Isothermal Amplification (Gold
Standard)
➔ Requires water bath not thermocycler
Treatment
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Praziquantel (for trematode and cestode infection)
➔ Mechanism of action: It increases the permeability of
the membranes of schistosome cells towards calcium
ions. The drug thereby induces contraction of the
parasites' muscle, resulting in paralysis in the
contracted state; prevents the worm from releasing
acetylcholinesterase, resulting in paralysis.
Control and Prevention
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Cerebral schistosomiasis
➔ The parasite reaches the brain because parasites are
in the blood.
➔ Migration of the worm through the cerebral venous
plexus (Batson plexus).
➔ Calcification around the eggs in the blood vessels
➔ Symptoms include convulsion, headache, and
paralysis
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Avoid swimming, wading, or walking in streams infested with
Oncomelania spp.
Prevent use of night soil (human excretion) as fertilizers
Proper excreta disposal, prevent animals to have in contact
with human feces
Provision of latrines and safe water
Snail control
Education
Proper sanitation
Case detection and treatment
DOH Schistosomiasis Control Program
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Esophageal varices
➔ Internal bleeding in the esophagus causing the patient
to choke.
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Partner Institutions
➔ Research Triangle Institute (RTI), International, Save
the Children, Plan International, WHO, DA, DepEd,
DILG, NIA, Academe, and LGUs
Policies and Laws
➔ Schistosomiasis Clinical Practice Guidelines
★ DM 2016-0212
★ AO 2009-0013
★ AO 2007-0015
Strategies, Action Points and Timeline
➔ Preventive Chemotherapy through Mass Drug
Administration
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Intensified Case Management
Promotion of Animal Health and Veterinary Public
Health under One Health Approach
Effective Intermediate Host Control and Surveillance
Water, Sanitation and Hygiene (WASH)
D. Schistosoma mansoni
Common name: Manson’s Blood fluke
Disease: Intestinal Bilharziasis
Epidemiology
❖ Endemic in Africa and certain parts of Middle East and South
America
❖ Reservoir hosts: Rodents, monkeys, and baboons
Morphology
❖ Egg – with lateral spine
❖ Cercaria – with forked tail
Life Cycle
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Intermediate Host: Biomphalaria and Tropicorbis/Gyraulus
(Freshwater snails)
Habitat: Mesenteric vein draining the large Intestine
ADULT MORPHOLOGY
➔ Integument with conspicuous tubercles
Male: 6-12 mm
➔ 6-9 testes
Female: 7-17 mm
➔ 300 eggs/day/worm
Pathology and Diagnosis
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Paired adult worms in copula
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Pathology is similar with S. japonicum
Circum-oval Precipitin Test (COPT)
Ultrasonography
Kato-Katz – to determine severity
Kato-Thick
Rectal biopsy
LAMP – Loop-Mediated Isothermal Amplification (Gold
Standard)
Treatment
❖ Praziquantel (for all trematode and cestode infection)
Control and Prevention
❖ Avoid swimming, wading, or walking in streams infested with
Biomphalaria and Tropicorbis/Gyraulus spp.
❖ Prevent use of night soil as fertilizers
❖ Proper excreta disposal, prevent animals to have in contact
with human feces
❖ Provision of latrines and safe water
❖ Snail control
❖ Education
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Proper sanitation
Case detection and treatment
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Schistosoma eggs in the bladder
E. Schistosoma haematobium
Common name: Vesical Blood Fluke
Disease: Urinary bilharziasis/Schistosomal hematuria
Epidemiology
❖ Endemic in Africa, other cases in Middle East but cases are
imported in Africa
❖ Reservoir Hosts – NHP’s and rodents
Morphology
❖ Egg – with apical spine
❖ Cercaria – forked tail
Diagnosis
❖ COPT
❖ Biopsy
❖ Urine Concentration Test
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ADULT MORPHOLOGY: Integument with minute tubercles
Male; 10-15 mm
➔ 4-5 testes
Female
➔ 1,500 – 3,500 eggs/day/worm
Treatment
❖ Praziquantel
❖ Metrifonate
➔ Anticholinesterase inhibitor
II. THE INTESTINAL FLUKES
A. Fasciolopsis buski
Common name: Giant Intestinal Fluke
Disease: Fasciolopsiasis/Fasciolosis
Epidemiology
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Endemic in East Asia, Southeast Asia including the Philippines,
and in South Asia
Reservoir Hosts: Pigs, dogs, and rabbits
Present distribution as of 2019 according to WHO
➔ Philippines is still included
➔ South Korea and Japan
Morphology
Life Cycle
❖ Intermediate Host: Bulinus spp (Freshwater snails)
❖ Habitat: Veins draining the urogenital organs; vesical and
pelvic plexuses of the venous circulation
❖ Life cycle is similar with S. japonicum
Pathology
❖ Ø Granuloma
➔ Formation/abscess, formation/fibrosis of the wall of
the urinary bladder, ureter, and urogenital organs.
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Except for schistosomes, all trematode eggs are operculated
Egg – 130-140 um, operculated, oval shape and straw colored
➔ Eggs are similar with Echinostoma and Fasciola
➔ Cannot be identified up to the species level
➔ Only up to the family level (e.g. Fasciolid Egg)
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The infective stage for the definitive host is the metacercaria.
Upon ingestion, the metacercaria will excyst in the duodenum
Final habitat: Duodenum of the small intestine
Eggs are voided in the stool. Embryonation will occur in the
environment
Miracidium will be released in the egg. Miracidium is the
infective stage for the primary intermediate host which are
freshwater snails
Primary Intermediate host: Segmentina spp and Hippeutis
spp.
Inside the snail host, each miracidium will divide forming
sporocysts. Each sporocysts will divide to form hundreds of
radiae. Each radia will divide to form cercariae. Cercariae will
leave the snail host to look for secondary intermediate host.
The cercariae will then form metacercaria.
Adult
➔ 20-75 mm
➔ No cephalic cone
➔ Unbranched ceca; Fasciola has branched ceca
➔ Testes: paired, dendritic
Adult form is similar with Fasciola except that it has no cephalic
cone; Fasciolopsis has no shoulders, no cephalic cone
The female organ, vitellaria and the testes are found in a single
organism; hence, hermaphroditic.
Ventral sucker is bigger than oral sucker
Pathology
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Diarrhea, hunger pains
Ulceration at the site of attachment; perforation
Obstruction of the bowel
Death caused by intestinal intoxication
➔ Due to the secretory products of the fluke
SAMPLE CASES
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Life Cycle
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Ingestion of imperfectly cooked or washed secondary
intermediate host
Secondary intermediate host: freshwater vegetables
➔ Water chesnut (Trapa bicornis) - found in Thailand,
Vietnam, and other parts of Southeast Asia)
➔ Water spinach (Ipomea aquatica) - Philippines
➔ Indian lotus (Nelumbo nucifera) – South Asia and
Divisoria
➔ Watercress (Rorippa nasturtium-aquaticum) Elsewhere
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Gastrointestinal: Fasciolopsis buski infection diagnosed
by upper gastrointestinal endoscopy
➔ 35-year-old immigrant from Vietnam to Taiwan
➔ Diagnosed with 2-month postprandial nausea
➔ Dietary history: Ingestion of uncooked vegetables
➔ Diagnosis: (Through endoscopy) 2.5 cm flesh-color,
oval shaped plaque lesion adherent to the medial wall
of the second portion of the duodenum.
➔ Treated with single dose praziquantel
➔ After 1 year, return from diagnosis, already free from
infection
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Rare cause of appendicitis: Mechanical obstruction due to
Fasciolopsis buski infection
➔ The patient is a 45-year-old female from Southeast
Asia complaining for right, lower abdominal pain
➔ Diagnosis: Appendicitis
➔ Physicians prescribed anti-inflammatory medication
but not responsive for 5 days
➔ Physicians used endoscopy for further diagnosis.
They found the flukes in the appendiceal orifice.
Fasciolopsis buski vomited out by a child; The first case
reported from Nepal
➔ 14-month-old child with travel history in India.
➔ Due to drinking of infested ponds
➔ First diagnosis was Urinary Tract Infection (UTI)
➔ No improvement when treated with meds for UTI
➔ Doctor gave praziquantel without diagnosis, after 12
hours, 4 adult Fasciolopsis were vomited
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Small bowel stricture and perforation: an unusual
presentation of Fasciolopsis buski
➔ Patient was diagnosed with peritonitis
➔ History: Ingestion of unfiltered water and consumption
of raw water vegetables
Diagnosis
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Stool Examination
Treatment
❖ Praziquantel
Control and Prevention
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Snail Control
Sanitation
Detection and treatment of cases
Education
Avoid eating raw/imperfectly cooked secondary intermediate
hosts
B. Echinostoma ilocanum
Common name: Garrison’s Fluke
Disease: Echinostomiasis
Epidemiology
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Distribution: Endemic in Thailand, Indonesia and Philippines
First found in male prisoners in the Philippines
Reservoir hosts: Rodents and Dogs
Distribution in 2019
Life Cycle
❖ Primary Intermediate Host: Gyraulus spp. And Hippeutis
spp.
❖ Secondary Intermediate Host: Pila conica (Garden snails in
the Philippines) and Viviparus javanicus (found in Indonesia)
❖ Mode of Transmission: Ingestion of imperfectly cooked
garden snails.
❖ In the Philippines, we consume ginataang kuhol.
Morphology
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Egg – 83-116 um, oval-shapel, operculated
Diagnosis must be in the family level (e.g., Fasciolid egg)
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ADULT MORPHOLOGY
➔ Reddish-gray
➔ 2.5-6.5 mm
➔ Anterior end has a collar of spines
➔ Testes: paired and lobed
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Eggs are voided in the stool. It will take two months before eggs
release miracidia. Miracidium will look for suitable Primary
Intermediate host. In snail tissue, miracidium will divide to
become sporocysts and then sporocysts will divide to form first
generation radiae. Each first generation radia will produce
second generation radiae. They will divide to produce
cercariae. Cercariae will leave snail host to look for secondary
intermediate host.
Inside the secondary intermediate host, cercariae will encyst
forming metacercariae
Metacercaria is the infective stage for the definitive host.
Migratory birds also served as reservoir hosts
Pathology
❖ Inflammatory lesions
❖ Intoxication
❖ Diarrhea
❖ In comparison to Fasciolopsis, Echinostoma infection is less
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severe due to its small size.
Diagnosis
❖ Stool examination
Treatment
❖ Praziquantel
Control and Prevention
❖ Snail control
❖ Sanitation
❖ Detection and Treatment of cases
❖ Education
❖ Avoid eating raw/imperfectly cooked intermediate hosts
C. Heterophyes heterophyes
Common name: Von Siebod’s Fluke
Disease: Heterophyiasis
Epidemiology
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Distribution:(early 2001) Nile delta, Turkey, Far East, Middle
East, Europe
Reservoir hosts: Fish-eating mammals
Morphology
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Eggs – have a small knob at posterior end (similar with
Clonorchis and Opisthorchis.)
➔ 28-30 um
➔ Eggs have opercular collar
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Adult fluke is 1.03 mm and pyriform shape
➔ Has big genital sucker
➔ Have three suckers
★ Oral sucker (OS)
★ Ventral sucker (VS)
★ Genital sucker (GT = Gonotyl)
➢ Bigger than the two suckers
➔ Testes are paired and ovoid
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A and B are metacercariae in fish muscles
Diagnosis: Only Heterophyid egg
Life Cycle
❖ Primary Intermediate Host: Pironella conica and Cerithidea
cirgulata
❖ Secondary Intermediate Host: Cyprinoid fish
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Pathology
❖ Inflammatory reaction
❖ Myocarditis
➔ Due to migration of adult worm (can penetrate/invade
blood vessels)
❖ Mucoid diarrhea
❖ Granuloma in the brain
➔ Due to migrating adults and eggs inside the body
➔ when the eggs reach the brain
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SAMPLE CASES
An endoscopic surprise in a child with chronic diarrhea
➔ Patient was a 9-year-old male in North India
➔ The patient experienced anorexia and loss 12 kg due
to diarrhea for 6 months
➔ Heavily infected with Heterophyes heterophyes
➔ Diet: Non-vegetarian
➔ Found mobile worms in intestine with endoscopy
Diagnosis
❖ Stool examination
Treatment
❖ Praziquantel
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Mode of Transmission: Ingestion of Imperfectly cooked
secondary intermediate host cyprinoid fish
Infective stage for the definitive host is the metacercaria
Metacercaria will excyst in the duodenum of small intestine
producing the adult fluke
Eggs are voided in the stool.
Mode of Transmission of Primary Intermediate host: Ingestion
of the Egg
Hatching of the egg occurs inside the primary intermediate
host. Egg will release the miracidium inside producing
sporocysts and then radiae and lastly cercariae.
Cercariae will leave the primary intermediate host and look for
secondary intermediate host (cyprinoid fish).
Once inside, cercariae will encyst into metacercariae in the
musculature of cyprinoid fish.
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Control and Prevention
❖ Snail control
❖ Sanitation
❖ Detection and Treatment of cases
❖ Education
❖ Avoid eating raw/imperfectly cooked intermediate hosts
III. THE LUNG FLUKE
A.
Paragonimus westermanni
Common name: Oriental Lung Fluke
Disease: Paragonimiasis
Epidemiology
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Distribution: Worldwide distribution (America, Africa, and Asia)
➔ 20.7 million are infected
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➔ 293 million at risk (2020)
Reservoir Hosts: Canines, Felines, Rodents
Paratenic Hosts: Swine, Wild, Boars
Philippine Prevalence (1984): 0.5-12%
➔ Sorsogon (2014)
➔ Samar (2014)
➔ Zamboanga del Norte (2014, n=836)
★ Pw: 6.7% (2.5-12.7%)
★ PTB: 1.9% (0.9-6.3%)
★ Co-infection: 0.3%
➔ Endemic foci (1979)
★ Batanes (1979)
★ Camarines Norte (1979)
★ Camarines Sur (1979)
★ Albay (1979)
★ Mindoro (1979)
★ Cebu (1979)
★ Negros (1979)
★ Cavite (1979)
★ Metro Manila (1979)
Cases in Bicol are high due to Kinagang (crab covered with
coconut meat and will be cooked in coconut milk)
Morphology
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Life Cycle
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Adult
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Coffee bean shaped
8-16 mm
Testes: lobed
by
side
★ Side
Paragonimus
gonads,
Primary Intermediate Host: Brotia asperata (Antemelania
asperata)
Secondary Intermediate Host: Sundathelphusa philippina and
Verunna literata (Talangka)
hence;
Egg
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Diagnostic feature: abopercular thickening, the
posterior part of the egg opposite to the operculum,
the anterior part of the egg.
★ oral sucker is as big as ventral sucker
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Ingestion of Imperfectly cooked or raw crabs
➔ Metacercaria can be found in the gills and muscles of
the crustacean (crab)
➔ The metacercaria will excyst in the duodenum,
penetrate the mucosa, will gain access to the
bloodstream via submucosa and will migrate to the
lungs.
➔ Final habitat: Parenchyma of the Lungs
➔ Eggs are voided in the sputum
★ Early morning sputum
★ In cases, sputum was ingested, eggs may
be found in the stool
➔ Hatching of the egg occurs in the environment
releasing the miracidium and then the miracidium will
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look for primary intermediate host via integument
penetration.
Miracidium is the infective stage for the snail host.
Inside the primary intermediate host, miracidium will
divide to form first generation sporocysts and then will
divide to produce second generation sporocysts then
will divide to form radiae and these will divide to
produce cercariae.
Cercaria will leave the primary intermediate host and
look for secondary host by invading the gills and
muscles of the crustacean and then will encyst
forming metacercariae.
Metacercariae is the infective stage for the
definitive host.
Pathology
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oral sucker is as big as ventral sucker
Egg
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Same with Tuberculosis
➔ Chronic productive cough
➔ Hemoptysis (Cough with blood)
➔ Dyspnea (Shortness of breath)
➔ Fever
➔ Weight loss
➔ Night sweats
130-150 um
Diagnosis
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Stool Examination
Sputum Examination (Early morning sputum)
X-ray
Treatment
❖ Praziquantel
Life Cycle
Control and Prevention
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Avoid eating raw/imperfectly cooked intermediate host and
paratenic hosts
Sanitation
Education
Treatment of cases
IV. THE LIVER FLUKES
A. Fasciola hepatica
Common name: Sheep Liver Fluke
Disease: Fascioliasis
Epidemiology
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Distribution: Distributed in over 90% of the world (in 2015)
➔ France, Algeria, Mediterranean, Brazil, and Latin
America
Reservoir Hosts: Undulates and Ruminants (Bison, Cattle,
Deer, Sheep, Hog, Rabbit)
Morphology
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Adult
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30 mm
With cephalic cone
Branched ceca (highly dendritic)
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Primary Intermediate Host: Lymnaea spp.
Secondary Intermediate Host: Freshwater vegetables
Final habitat: Hepatic biliary ducts
Metacercaria is the infective stage for the definitive host
Adults are in the parenchyma of the liver but eggs are in the
biliary ducts and hepatic portal vein
Pathology
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Acute Phase
➔ Fever
➔ Hepatomegaly
➔ Abdominal pain
Chronic Phase
➔ Urticaria
➔ Colic and Gastric Pain
➔ Hyperplasia of the bile ducts
➔ Pipestem liver
➔ Jaundice
➔ Necrotic lesions of the liver
➔ Fibrosis of the liver
★ Immune reaction against the worm and the
eggs producing collagen deposit around the
affected areas
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suppressant)
The whole length of transverse, descending, and sigmoid colon
were filled with Fasciola adults and eggs.
Mesocolon was also perforated filled with adult worms
Diagnosis
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Serology
Stool Examination
CT scan, ultrasound
Treatment
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Halzoun (General term due to many pathogens causing the
disease)
➔ Mode of Transmission: Ingestion of raw liver
➔ Symptomatology: Pain, edema, and bleeding
★ The parasite will stick into the pharynx
causing Halzoun symptoms like pricking
throat sensation, coughing, and sneezing.
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Bithionol
➔ Potent inhibitor of soluble adenylyl cyclase
Triclabendazole
➔ Inhibits microtubule formation
Surgery
B. Fasciola gigantica
Common name: Giant Liver Fluke
Epidemiology
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Distribution: Africa, Hawaii, Asia
Reservoir hosts: Camels, Cattles, Water buffaloes, Wild hogs
Morphology
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Adult Fasciola gigantica is bigger than Fasciola hepatica
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Eggs – 160-190 um
Ectopic Infection
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Peritoneal cavity
Intestinal wall
Lungs
Subcutaneous tissue
Sample Case: Ectopic Human Fasciola hepatica Infection
by an Adult Worm in the Mesocolon
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A 56-year-old female was admitted to a local hospital with
discomfort and pain in the left lower quadrant of the abdomen
for 10 days.
Have dietary history of Lotus leaf powder (appetite
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C. Clonorchis sinensis
Common name: Chinese/Oriental Liver Fluke
Disease: Clonorchiasis
Epidemiology
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Life Cycle
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Distribution: Worldwide – 15 million (2020)
➔ East Asia, Taiwan, Vietnam
Reservoir hosts: Fish-eating mammals
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Same with Heterophyes heterophyes
Primary Intermediate Hosts: Parafossarulus, Bulinus,
Alocinma, and Melanoides
Secondary Intermediate Hosts: Cyprinoid (freshwater) fish,
shrimps
Habitat: Distal bile capillaries
Morphology
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Egg - 28-35 um
➔ Similar with Heterophyes heterophyes with posterior
knob and collars
Pathology
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Adult
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10-25 mm
Testes: branched (dendritic)
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Mostly asymptomatic
Mild cases:
➔ Abdominal pain
➔ Diarrhea or Constipation
Severe cases:
➔ Abdominal pain
➔ Nausea
➔ Diarrhea
Chronic Infection: 30 years
➔ Hepatomegaly
➔ Malnutrition
➔ Liver and bile duct cancers
➔ Cholangiocarcinoma (CCA)
★ Cancer of the bile ducts due to physical and
chemical injury caused by the worm can
lead to cancer formation.
★
Clonorchis sinensis excretory-secretory
products increase malignant characteristics
of
cholangiocarcinoma
cells
in
three-dimensional co-culture with biliary
ductal plates.
D. Opisthorchis felineus
Common name: Cat Liver Fluke
Disease: Opisthorchiasis
Epidemiology
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Distribution: East, Central, South Europe
Morphology
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Adult: 7-12 mm
➔ Testes: Clover-leaf shape
E. Opisthorchis viverrine
Common name: Southeast Asian Liver Fluke
Epidemiology
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Egg: 30 um
➔ Same with Heterophyes heterophyes, with posterior
knob and collars
Life Cycle
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Same with Clonorchis
Primary Intermediate Host: Bithynia leachi (Freshwater snail)
Secondary Intermediate Host: Cyprinoid fish
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Distribution: Thailand, Laos, Southeast Asia
Morphology
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Adult: 7-12 mm
➔ Testes: Clover Leaf Shape
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Egg: 30 um
➔ The eggs are operculated and possess prominent
opercular ‘shoulders’ and and abopercular knob.
Life Cycle
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Same with Opisthorchis felineus
Primary Intermediate Host: Bithynia goniomphalus, B.
funiculate, B. laevis
Secondary Intermediate Host: Cyprinoid fish
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