Parasitic helminth of human importance Disease: Schistosomiasis Agent: Schistosoma 4 species: Differential pathogenicity Mollusc intermediate host Water-borne Digenean infection

Platyhelminths : Flukes Intestinal flukes e.g. Fasciolopsis buski, Echinostomes Liver flukes e.g. Fasciola hepatica, Opisthorcis, Clonorchis Lung flukes e.g. Paragonimus Blood flukes e.g. Schistosomes

Species of Schistosomes Schistosoma mansoni : Africa, Brazil, Venezuela, parts of the Carribean, Puerto Rico : mesenteric veins of colon, no imp reservoirs Schistosoma japonicum : Far East, parts of China, Japan, Phillipines, Indonesia : mesenteric veins of small intestine, many imp reservoirs. Produces more eggs

Species of Schistosomes Schistosoma haematobium : Africa, Cyprus, S. Portugal, isolated focus in India, recently Jordan : Vesicles assoc. with bladder, characteristic hematuria Schistosoma mekongi : Mekong river basin, Cambodia Schistosoma intercalatum : W and C Africa

Symptomatology Egg laying produces ACUTE stage of disease Intestinal schistosomiasis Urinary schistosomiasis Hepatosplenic schistosomiasis Bladder cancer Pulminary & cerebral complications

King et al. 2005: Lancet Recent meta analysis of disability due to Schistosomiasis: significant and underestimated burden of subtle morbidity (anemia, chronic pain, diarrhoea, malnutrition)

Immunology and pathology Schistosomula : antibody-dependent cell mediated cytotoxicity Antigenic disguise Granuloma formation & modulation Periportal fibrosis, cirrhosis, pulmonary schistosomiasis, bladder fibrosis Placental & neurological involvement

Schistosomiasis and pregnancy Currently schistosomes infect about 40 million women of child-bearing age but we know little of associated morbidity Limited evidence of poor birth outcomes including birth weight Friedman et al. (2007)

Diagnosis Detection of eggs in faeces or urine Rectal biopsy Immunodiagnosis Detection of proteinuria/hematuria urine (sedimentation/filtration/polyc arbonate filters, reagent sticks) faeces (formyl ether sedimentation, Kato-Katz, KOH digestion) indirect (new dipstick assay anti-CAA sandwich ELISA)

Schistosome eggs

Epidemiology : reservoir hosts, snail hosts, irrigation and other water projects Treatment : Praziquantel Control (integrated approach preferable) Chemotherapy Education and sanitation Mollusciciding Vaccine development