schistosomiasis

Overview Epidemiology Pathogenesis Diagnosis and treatment Vaccination Control Prevention

Theodor Bilharz (1851)

Pirajá da Silva (1908)

2nd most socioeconomically devastating parasitic disease.

3 species that infect humans

Origin› Africa› New World

Intermediate host› Human waste in water› Survival of these parasites depends on

human habits of polluting water with their own feces.

Most Vulnerable people:› Farmers› Fishermen› Children

Moslem countries› They perform ablution

Factors that influence transmission› Economic level› Education level› Sex

Males have the highest rates of infection and are the most intense

› Age

Protective immunity to super infection is elicited› By repeated exposure to cercaria› Presence of adult worms

Resistance to re-infection › Adults (most apparent)› Children (least resistant)

During the age of 8 to 18 years of age

Is unusual › Due to eggs and not to adult worms

Has three phases› Migratory

From the time of penetration until maturity egg production

Symptom less› Acute› Chronic

Acute Phase › Katayama Fever› Schtistosome being producing eggs› Symptoms include

Chills and fever Fatigue Lymphadenopathy

› Many eggs are carried by the hepatic portal circulation back to the liver.

Chronic Phase › Endemic areas

Asymptomatic› Intestinal

Mild, chronic, bloody diarrhea Abdominal pain Lethargy

› Schistosomiasis haematobia Pain on urination and blood in urine

8% of cases of infection S. japonicum and S. mansoni development of egg granulomas and fibrosis in the liver seriously impedes portal blood flow. › Enlargement of the spleen

S. japonicum tend to involve the small intestinal › Eggs of S. japonicum reach the brain more

often › Of the other 60% of all neurological diseases

of Schistosomiasis all brain lesions are due to S. japonicum

S. haematobium is the least seroius › Pain is most intense at the end of urination › Strong evidence nmj mnb that it cause bladder

cancer.

Identification of eggs un stools or urine

› Kato-Katz technique Tissue biopsy Antibody detection

Schistosomiasis is readily treated using a single oral dose of the drug Praziquantel annually

Education

Control by Chemotherapy› Lowered from 60.3% to Helling-Giese

1996.8% one after treatment with parziquantel

Vector Control

Control of snails Environmental management measures

› Stream channelization› Seepage control› Canal lining › Canal relocation with deep burial of snails,

can prevent increase in transmission Procambarus clarkii

Would have great potential value

Protection can be conferred by irradiated cercariae

A number of parasite-derived antigens confer partial protection against re-infection when used to immunize mice, rate, and other animals.

Avoid Swimming

Drink Safe Water

Heat bath water for 5 minutes at 150 F

Vigorously towel down after accidental contact with water.

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