Disease

Schistosomiasis

Infectious Agents

S. mansoni, S. haematobium, S.japonicum

http://www.abdn.ac.uk/biologicalsci/research/integrative/images/vector8.jpg

Cercariae

http://home.austarnet.com.au/wormman/paraimg/smanscer.jpg

http://biology.unm.edu/biology/esloker/pi/Cercaria.jpg

Prevalence

200 million people worldwide

Distribution:

http://www2.ncid.cdc.gov/travel/yb/utils/images/map4-10_lg.gif

Incubation Period

About 3 months since fresh-water contact

Reference

Transmission

Through feces/urine of infected individuals into several species of fresh-water snails. Eggs hatch and larva grow and mature in snails. Worms leave snails and are allowed to then swim freely in water for up to 48 hours. Parasite then penetrate the skin of persons in contact with contaminated water.

Life Cycle:

Reference

http://www.tesd.k12.pa.us/stoga/AfricaLW/schistosomiasis.jpg

Symptoms/ Clinical Features

Pathology of S. mansoni and S. japonicum schistosomiasis includes: Katayama fever, hepatosplenomegaly, hepatic perisinusoidal egg granulomas, Symmers’ pipe stem periportal fibrosis, portal hypertension, and occasional embolic egg granulomas in brain or spinal cord. Pathology of S. haematobium schistosomiasis includes: hematuria, scarring, calcification, squamous cell carcinoma, and occasional embolic egg granulomas in brain or spinal cord.

http://upload.wikimedia.org/wikipedia/commons/2/27/Schistosomiasis_itch.jpeg

Diagnosis

Stool or urine sample and a blood test to identify eggs.

Treatment

Praziquantel is the drug of choice most often used today.