Arthropod borne Diseases
By
Dr. Sabry Ahmed Salem
Prof. of community medicine
Environ mental health &
occupational medicine
Classification According to causative agent
I. Bacterial :
- Tick borne relapsing fever
- Louse borne relapsing fever
II. Viral:
- Yellow fever
- Rift valley fever
- Dengue(break bone) fever
- Arbovirus encephalitis
- Sandfly fever
III .Parasitic:
- Malaria
- Filarial
- leishmaniasis
IV. Rickettsial:
- Typhus group (epidemic, endemic and scrub
typhus).
- Spotted fever (rocky mountain fever).
- Trench fever.
Plague
Definition: Acute Infectious – insect – borne disease
gram (-)ve bacilli.
Causative: Yersinia (Pasteurella pestis) , Gram –ve,
bipolar stained and killed by heat, sunlight,
and disinfectants.
Reservoir of infection:
- Rats and other rodents (wild) flea.
- Domestic rodents through fleas outbreak (epizootic)
- Death of rats, fleas leave rats and causes epidemic
of plague.
Vector: rat flea (xenopsylla cheopis).
-Rat to rat then them rat to man
Mode of transmission:
1. Flea faeces of flea: lead to contamination of skin
abrasions.
2. Flea bite.
3. Droplet infection: from man to man in pneumonic cases.
Incubation period: International period is 6 days.
Clinical picture: 3 types:
1. Bubonic plague: lymph nodes usually inguinal
2. Septicemic plague.
3. Pneumonic plague: fatal.
Diagnosis:
1. Clinical picture.
2. Laboratory: sample from affected blood, lymph
node or sputum (bipolar-stain) bacilli (G-ve) with
characteristic bipolar staining.
Prevention:
1- General prevention
Rodent control: by
– removal of breeding places.
- Rat-proof buildings.
- Trapping.
- Insecticides.
- Fumigation by SO2 & HCN of cargoships .
Flea control: by
Ventilation and dust control.
Removal of breeding places.
Insecticides (D.D.T dusting): dusting breeding places
and rats holes and runs
1- Specific protection: by
1- Active immunization : to risk- groups
a- Otten's vaccine. Live- attenuated , single dose , 1 ml S.C,
causes about 6 months- protection.
b- Haffkin’s vaccine Killed vaccine, 2 doses:
0.5 ml (after 7-10 days) 1 ml Sc gives few months protection.
2- Chemoprophylaxis:
to contacts and at-risk group. Tetracycline
250mg/6hrs. for 6 days.
3- International (Quarantina measures):
Protection of ports against rodents.
Deratting certificate from cargoship (fumigated by
SO2, HCN) and valid for 6 months.
Control:
Case: Notification, isolation, heavy dusting with DDT
10%, to any place where fleas may be found.
Treatment by chemotherapy and release when
clinically free.
Contacts:
- Dusting with DDT 10%.
- Surveillance for 10 days.
-Chemoprophylaxis: tetracycline 250 mg/ 6 hrs
for 6 days.
Epidemic measures:
-Mass Flea control before rat control.
-Chemoprophylaxis of at-risk groups.
-Case finding management.
* Causative agent: plasmodium (protozoon) having
four species
4 species
1- P. Vivax
- Benign tertian (vivax) malaria
2- P. Ovale
- Ovale malaria (Benign tertian, less
common).
3- P. Malariae
4- P. Falciparum
* Vector:
Extrinsic I.P:
- Quartan malaria.
- Malignant malaria.
- Female Anopheles mosquito with
sporozoites in their salivary glands.
Average: 2 weeks.
* Reservoir of infection:
a. Infected person (patient) having gametocytes
in his peripheral blood causes infection if
infective to mosquito vector ♀.
b. Patient can be a carrier of several plasmodial
species at the same time.
* Period of infectivity:
For many years or life so long as gametes are
present in the blood and no treatment is given.
Relapses:
In P. vivax and ovale may occur more than 3 years
after the first attack.
In P. falciparum disappears within 1-2 years.
P. malariae shows prolonged low. Level
asymptomatic parasitism.
* Mode of transmission:
a- Insect- bite by Infective female Anopheles
mosquito
sporozoites ( the infective stage in
the salivary glands of mosquito).
b- Direct- transmission: by inoculation of
contaminated blood (transfusion).
* Incubation period:
a- average: 2 weeks
- falciparum malaria (12 days)
- vivax malaria
( 14 days)
- quartan malaria
(28 days)
- ovale malaria
(17 days)
•Clinical picture and diagnosis
1- Attacks of rigors, fever then sweating:
- Rigors or cold shivers with fever ( ½ -1 hour).
- Hot stage; fever (1 to 4 hrs.)
- Sweating stage: Profuse sweating (1-4 hrs) the
above attacks are due to destruction of R.B.Cs
and release of pigments and toxins.
2- Anaemia (hemolytic)
3- Hepato- splenomegaly: (due to engulfed parasites by the
recticulo-endothelial cells 
hypertrophy).
4- Malignant malaria (P. faciparum) may be:
a-Attacks are not well defined and fever may be continuous or
irregular. i.e. atypical attack
b-Clumping of the affected R.B.Cs leads to occlusion of blood
capillaries causing lesions according to the affected area.
C. May be severe and fatal taking different
forms
i- Cerebral form: headache, fever, convulsions and
coma.
ii- Algid form: collapse and peripheral circulatory failure.
iii- G.I.T form: severe diarrhea or dysentery
dehydration.
d. Black water fever. Acute intravascular haemolysisi of
R.B.Cs caused by repeated attack or prolonged
course of P. falciparum infection and manifested by:
hemolytic anemia (+++), hemolytic jaundice, high
fever, hemoglobinuria (Dark Red urine) and high
Mortality Rate.
5- Nephrosis, specially in children may occur with P.
falcipartum infection (pus And casts in urine).
6- Abortion or congenital infection when the pregnant is
infected with malaria.
* Diagnosis:
Clinically: Acute attacks of chills, fever and
sweating are suggestive.
Laboratory: blood film examination for the parasite
during the febrile attack.
* Prevention and control of malaria:
I- Control of human reservoir (cases)
1- Case- finding:
During health appraisal by blood films and clinical
examination.
During survey studies and malaria campign for chronic
cases and asymptomatic infections.
2- Treatment of diagnosed cases by proper
chemotherapy.
3- Re-examination: after treatment.
II- control of vector:
1. Eradication of breading places (water collections).
2. Control of breading places (larvae) collections)
3. Destroying the adult mosquito by insecticides with
temporary (inside the building) or permanent
(residual) outside the buildings.
III- Protection of man:
1. Prevention of mosquito to reach man by: screening,
Animal barrier & netting.
2. Protection of man against mosquito bites by,
protective clothes, netting of beds & application of
repellents.
3. Specific prevention by chemoprophylaxis.
* Chemoprophylaxis: for visitors to endemic areas:
Chloroquine : Antimalarial drug is given in suitable
dose one week before traveling and continue for 2
weeks after leaving Chloroquine is the drug of
choice and the prophylactic dose may be one tablet
/ week.
* Eradication of malaria:
Is the elimination of malaria in a certain locality based
on destruction of the mosquito vector in a timelimited period. Methods of implementation:
i.e. requirements:
Survey study of vector to put a plan of work.
Mass application of insecticides (residual) for all inhabited premises of the locality to be repeated
yearly for 3 years or more.
1. Supporting eradication by mass, case finding and
treatment and chemoprophylaxis and health
education of the public.
2. Follow- up of work by survey study to check
fulfillment (evaluation) and maintenance of
eradication. (i.e. to check progress of eradication)
• Malaria survey:
It a field study to assess the magnitude of malaria
problem in a given locality and study the ecological
factors determining spread and endemicity of the
disease.
I. Objectives: - Measuring the magnitude of the
problem .
- Studying the ecological factors.
- Planning for prevention & control.
II. Steps: - Planning. - Preparation. - Investigations.
- Tabulation of data.
- Analysis of data.
- Report- writing.
III. Investigations: Locality. - Infection in man.
Insect vector.
*Investigations
1- Locality: - Map showing water channels and
collections, cultivated land and houses.
- Climate.
- Population data.
2- Infection in man: Examination of children
aged 2-9 years for finding malariometric indicies.
Or malaria indices
a- Spleen index: % of examined children with
splenomegaly.
N.B: Non specific and ONLY valid in areas free of
parasites associated with splenomegaly.
b- Parasite index: % of examined children having malaria
parasites in blood.
* This is the Direct specific index of malaria infection.
3- Insect vector (biological environment)
a- Study of breeding places.
Sampling of water collections in the area to find
anopholes larvae and pupae.
b- Study of adult mosquitoes
Density and habits of anopheles mosquitoes in the building
of the area.
Collection of mosquitoes to be examined for specific
malaria indices which include:
Oocyst index: % of examined anopheles mosquitoes having
Oocysts in stomach wall.
Sporozoite index: % of examined female anopheles
mosquitoe, having sporozoites in salivary glands. (more
valid and specific for the infection rate of the mosquito
I. Oocyst index: % of examined anopheles mosquitoes
having Oocysts in stomach wall.
II. Sporozoite index: % of examined female anopheles
mosquitoe, having sporozoites in salivary glands. (more
valid and specific for the infection rate of the mosquito
vector).
• Malariometric indices:
- 2 for man
- 2 for mosquito
a- in children aged 2-9 years
- Spleen index
- Parasitic index.
b- For mosquitoes
- Oocyst index.
- Sporozoite index.
Filariasis
Definition: Parasitic, disease of lymphotics and
lymph nodes, may ending by elephantiasis.
Causative agent: Wuchereria Bancrofti (is the most
important).
Reservoir:
Man: as a case: Gravid female worm puts
microfilaria which appear in peripheral blood at
night.
Vector: Mosquito Culex pipiens
(Insect bite): the mosquito takes microfilariae
with blood meals).
Mode of transmission: by mosquito (culex) bite
Clinical picture & pathology:
Acute stage:
- Lymphadenitis and local lymphagnitis
Chronic stage:
a. Lymphatic dilatation: i.e. lymph varies.
b. The Lymphatic Vs. rupture  chyeuria. Chylothorax,
chylous ascites & chylocale.
c. Then Elephantiasis: commonly legs and scrotum.
Diagnosis:
Clinical picture: suggestive in endemic areas.
Laboratory: Blood film (at night) shows microfilariae.
Prevalence:
Endemic in Egypt at Giza and Rasheed as foci of
endemicity due to presence of reservoir of infection
(cases) and breeding of mosquito vector.
Prevention:
1- Mosquito control: (Place, larvae, adult mosquito)
a. Eradication of breeding places.
b. Control of breeding places by fish (Gambusia
affinis ) and insecticides (larvae).
c. Adult mosquito control: by insecticides for
temporary or residual affect, outside and inside
houses.
2- Man protection against mosquito bite by :
a. Screening.
b-Animal barrier.
C-Protective clothes and netting of beds.
a. Repellents application.
Control of filariasis
-Case finding.
- Treatment (Hetrazan, filiran).
Filariasis compaign:
In endemic areas:
Survey study.
Mass case
finding and treatment.
Vector eradication or control.
Arthropod borne Viral diseases
Caused by RNA virus of (Arboviruses) & Arthropod –
borne infection
Reservoir of infection:
A- Animals - Rift valley fever
- Hemorrhagic fever.
B- Man
- Encephalitides
- Jungle yellow fever.
- Urban / rural yellow fever
- Dengue.
- Sandfly fever
Vectors:
Biting insects as mosquitoes, sandfly and ticks.
Yellow fever
Definition:
Acute infectious arthropod- borne viral disease.
Causative agent:
Yellow fever virus (arbovirus).
Reservoir of infection:
Man (cases): in urban / rural yellow fever.
Monkey: in jungle yellow fever.
Vector: female Aedes aegypti (♀) in Urban type.
Female aedes African usually in Africa, Jungle
yellow fever. Hemagogus in America.
Mode of transmission:
Bite of infective mosquito
How man acquires infection
1. Entering the jungle: Y. f is endemic.
2. Monkey strays into human settlement and bitten by
A-aegypti mosquito causes man infection.
3. Flying mosquitoes outside the forest for short
distance causes man infection.
Incubation period; About 3 –6 days. (6 days
international)
Susceptability:
All ages and sexes get urban Y.F.
Young adult males who work in the Jungle if get
infection it is occupational disease.
Clinical picture:
Hepatitis with liver necrosis, kidney dysfunction.
Fever, Jaundice, hemorrhage and albuminuria.
Diagnosis:
Clinical picture.
Laboratory : by demonstration of antibodies
(neutralizing, complement fixing and
haemoaglutination Abs.).
Immunity:
Natural acquired immunity after disease, absolute
immunity.
Artificially induced after active immunization by 17-D
vaccine produces absolute immunity for at least 10
years.
Prevention:
1- Mosquito control:
In jungle Y.F. is impractical.
In urban Y.F : anti- larval and anti- adult measures.
2- Specific prevention by vaccination
a- 17-D. vaccine: live- attenuated, prepared in chick- embryo,
0.5 ml SC, protection after 10 days for at least 10 years.
b- Dakar vaccine:
Live otten. / prepared in mouse-brain, by skin
scarification may lead to encephalitis.
Not used on international level by WHO.
3- International measures
To prevent introduction of Y.F from endemic areas to
recipient areas (e.g Egypt).
1- valid international vaccination certificate is required for
- Travelers between endemic and recipient areas.
- Aircrafts, using airports of endemic areas and employees.
Validity : begins after 10 days of vaccination. And
lasts for 10 years.
If the certificate is not valid (i.e. not available or the
travelers arrive before 10 days of vaccination)
isolation until the certificate becomes valid with
maximum 6 days.
b- Disinfections of any air craft leaving an endemic
area for receptive area by aerosol spray of
insecticide: shortly before and also on arrival if
necessary.
c- Quarantine of imported monkeys at receptive areas.
Rift valley fever (R.V.F)
-Acute viral, zoonotic arthropod- borne disease was
introduced into Egypt in 1977 from East & south Africa
causing an outbreak in animals and was transmitted to man.
-Causative agent: specific virus (Phlebovirus subgroup).
-Reservoir: cattle & sheep.
-Vector: Culex mosquito.
- Mode of transmission:
1.Culex bite.
2.Handling of diseased animals or their tissues
(occupational infec)
-I.P: 3-7 days.
Clinical picture (C/ P):
Mild form: fever, influenza. Like picture and usually selflimited.
Severe form (rare): haemorrhage, liver necrosis, retinal
damage and encephalitis.
Diagnosis: 1- Clinically : nonspecific.
Laboratory: + ve serum antibodies.
Prevention:
1. Vector control or eradication.
2. Protection of man against mosquito bite.
3. Protection of man against occupational
infections.
Dengue (Break bone F.)
-Acute infectious insect- borne disease
-Causative agent: Dengue virus.
-Reservoir: Man (case).
-Vector: Aedes aegypti.
-Mode of transmission: insect bite.
-Clinical picture:
-Severe pain in the joints, bone and muscles for
some days followed by recovery.
-Dengue F. may be associated with hemorrhagic
manifestations and renal involvement
(hemorrhagic dengue).
•Diagnosis:
Clinically: nonspecific.
Laboratory: +ve serum antibodies.
* Prevention:
Vector control or eradication.
Protection of man against bite of mosquito.
Leishmaniasis
A group of diseases caused by a protozoon
leishmania is classified into:
1. Cutaneous leishmaniasis.
2. Viscereal leishmaniasis.
3. Muco-cutaneous leshmaniasis.
I- causative agent:
Cutaneous L caused by L. Tropica.
visceral L by L. Donovani.
muco-cutaneous by L . braziliensis.
II-Reservoir of infection:
- C.L :  man
-V.L:man and do
-M.L.: man and rodent
III- Vector: Phlebotomus papatassi(sand fly)
V- Mode of transmission:
-Cutaneous L. through Sand fly bite & contact with
skin lesions of the case.
-Visceral L.due to infective sandfly bite.
-Muco-cutaneous L. due to infective sandfly bite.
IV- Clinical picture:
1. Cutaneous L. shows Single or multiple
ulcerating lesions on the exposed skin.
2. Kala-azar In adults. Prolonged fever,
splenomegaly, hepatomegaly,
lymphadenopathy, cachexia & death
of untreated cases.
In infants: affects young children and gives the
same picture as adults.
1. M.C Leishmaniasis: Ulcerating skin lesions
(nose & mouth) destruction.
VI- Diagnosis:
a. Clinical picture: suggestive in endemic areas.
b.Laboratory:
- Stained smear (from organs, ulcer and blood)
shows L. bodies.
- Culture if indicated.
Prevalence of leishmaniasis :
* Alexandria region has an endemic focus.
* Clinical infection leads to lasting immunity.
* L. donovani infection causes cross immunity.
Prevention of Leishmaniasis (L. Tropica, L.
Braziliensis)
1. Sandfly control.
2. Protection of man against sandfly bites.
3. Control or destroying dogs and rodents.
4. Health education of the public to avoid contact with
skin lesions of others.
5. Specific prevention by trial of live- L. tropica vaccine
in endemic areas.
Control of Leishmaniasis
Early case finding (Case-finding) and treatment
Covering skin lesion to avoid infection of the
vector and contacts.
Disinfection of the contaminated objects of the
case.
Health education of the case and contacts.
N.B: Prevention of L. donovane includes:
Control of sandfly.
Protection of man against phlebotomus paptassi bite.
Rickettsial diseases
Are classified into 3 groups:
I- Typhus group
Ag
organism
reservoir
- Epidemic typhus
R.prowazeki
- Endemic typhus
R. mouseri
- Scrub typhus
R. Tsutsugamushi
Man
Rat
vector, proteus
louse, Ox 19
Flea, Ox19
Rodents Mite, Ox K
II- Spotted fever group “Scrubtyphus”
- Rocky mountain S.F
Ox19, Ox2
R.ricketsi
Dogs & Rodents
- Boutonneuse fever
Ox2
R. conori
Rodents
Tick Ox19,
- Rickettsial pox
R. Akari
Mice
Mite
III- Trench fever
R. Quintana
Man
Lous
- Fever coxiella
burnetti
Rats
ticks.
Tick
Transovarian transmitted R-diseases
Organism transmitted to progeny through the ova.
e.g. 1- Hard tick - American spotted fever.
- Boutonneuse fever
- Q- fever
2- Soft tick  Q- fever.
3- Mite (trambicula akamushi)  scrub typhus.