Schistosomiasis
目次
schistosoma is distinct from other trematoda
- trematode中schistosomaは他のtrematodeと異なる特徴を持つ
| schistosoma | other trematode |
|---|---|
| transmitted to human by percutaneous invasion of cercariae |
transmitted to human by oral ingestion of metacercariae |
| male and female separated 雌雄別体 | hermaphrodite雌雄同体 |
| does not require 2nd intermediate host (no metacercariae stage) |
requires 2nd intermediate host |
Schistosoma japonicum
- Katsurada Fujiro found 26 May 1904 from a cat in Yamanashi（水腫腸満）
- Fujinami Kan found 30 May 1904 from a murder victim in Katayama, Hiroshima（片山病）
- found egg in 1904 in Saga（奇病）
pathogenesis
- adult female paired by male migrate to messenteric vein from portal vein and lay eggs into messenteric venule, which are secreted from messenteric venule to intestinal lumen
- eggs also reach urinary bladder or genital tract and generate inflammation, followed by necrosis of tissue and perforation to intestine, resulted in extracorporeal distribution of egg via stool
- eggs are also distributed in liver and cause inflammation resulting in cirrhosis
- inflammation is exclusively due to egg
- adult pairs do not cause disease per se
treatment
- praziquantel was discovered only in mid-1970s in Germany
control
- only way to control is eliminate intermediate hosts, snails - Oncomelania nosophora 宮入貝
