Schistomiasis, also known as Bilharziasis
Blood flukes (schistosoma) 3 species most commonly affecting humans:
Spread by fresh water snails
- Has huge socio-economic consequences in the tropics.
- S. haematobium found in Africa and the Middle East
- S. japonicum found in the Far East
- S.mansoni is the most widespread, found mostly in South Americ the Caribbean, Africa the Middle East.
- Fresh water snail vectors release cercariae that penetrate skin (during swimming/paddling)
- Causes itchy popular rashàcercariae shed their tails to become schistosomulesàmigrate to the lungs and liver where they grow into adult form.
- 2 weeks later ‘Katayma fever’ = initial immune reaction to worm maturation and shedding of eggs.
- Approx 2 months later, flukes are mature and migrate to their resting habitats.
Acute: Katayama fever
S.mansoni and S.japonicum
- Both favour mesentaeric veins
- Lead to intestinal polyps, blood
- Stained stools, hepatic fibrosis and portal hypertension.
- Favours bladder veins
- Lead to urinary obstruction, polyps and
- Bladder cancer(squamous cell) Hydronephrosis, pyelonephritis, renal failure.
- Transverse myelitis.
- Microscopy for eggs in stool, urine or biopsy.
- Serology in non-endemic areas
- Renal tract US
Avoidance of fresh water contact in endemic areas.