SCISTOSOMIASIS: A REVIEW

Abstract

Schistosomiasis is an acute and chronic parasitic disease caused by blood flukes (trematode worms) of the genus Schistosoma. People are infected during routine agricultural, domestic, occupational, and recreational activities, which expose them to infested water. Transmission occurs when people suffering from schistosomiasis contaminate freshwater sources with their excreta containing parasite eggs, which hatch in water. In the body, the larvae develop into adult schistosomes. It is estimated that at least 90% of those requiring treatment for schistosomiasis live in Africa. Schistosomiasis mostly affects poor and rural communities, particularly agricultural and fishing populations. Symptoms of schistosomiasis are caused by the body’s reaction to the worms' eggs. Intestinal schistosomiasis can result in abdominal pain, diarrhea, and blood in the stool. Liver enlargement is common in advanced cases, and is frequently associated with an accumulation of fluid in the peritoneal cavity and hypertension of the abdominal blood vessels. Schistosomiasis is diagnosed through the detection of parasite eggs in stool or urine specimens. Antibodies and/or antigens detected in blood or urine samples are also indications of infection. The control of schistosomiasis is based on large-scale treatment of at-risk population groups, access to safe water, improved sanitation, hygiene education, and snail control. A clean water supply, sanitation, vector control, and health education can interrupt the spread of schistosomiasis. Early antiprasitic treatment, (i.e praziquantel) especially with acute schistosomiasis, may allow people to recover completely without developing chronic disease. A few people get the disease but recover completely. Even patients with early chronic disease can improve with drug treatment. However, the prognosis is worse for people who have other health problems (for example, with a suppressed immune system, HIV, or chronic infections such as malaria) and subsequently get infected with Schistosoma. People with chronic disease may improve with careful antiparasitic drug treatments and symptomatic treatment of the complications associated with schistosomiasis.