Schistosomiasis is caused by flatworms of the Trematoda class. These occur in different regions of the world, and in Brazil, the person responsible for the disease is the Schistosoma mansoni. This one has the human species as ultimate host, and freshwater snails of the Biomphalaria genus, such as intermediate hosts.
Infected people allow other individuals to acquire the disease by releasing parasite eggs in their feces and urine, when these are deposited in rivers, streams and other freshwater environments; or when they reach these places by floods.
In the water, the larvae - called miracidia - are released and only continue their life cycles if they lodge in snails of the Biomphalaria genus. These have as main characteristic the shell flattened on the sides and grayish brown in color.
The larvae, now called cercariae, develop and are released into the water. In contact with human skin and mucosa, penetrate the organism and can cause inflammation, itching and rednesso in these regions. There, they develop, reproduce and eliminate eggs from veins in the liver and intestine, obstructing them.
You symptoms, when they appear, appear approximately five weeks after contact with the larvae.
At acute phase (the most common), the disease manifests as skin redness and itching, fever, weakness, nausea, and vomiting. The individual can also have diarrhea, alternated or not by intestinal colds.
At chronic phase, liver and spleen may increase in size. Bleeding, with release of blood in vomit and feces, and an increase in the abdomen (water belly) are other possible manifestations.
O diagnosis it is done via stool exams in three collections, where the presence of worm eggs is verified; or by biopsy of the mucosa of the end of the intestine. There is also a way to diagnose it by checking, in a blood sample, the presence of specific antibodies.
O treatment it is made with antiparasitic drugs, usually in a single dose.
THE prevention it consists of identification and treatment of sick people, basic sanitation, fight against snails, and information to the population at risk. Avoiding contact with backwater or runoff and wearing appropriate clothing when coming into contact with water suspected of being infected are individual measures necessary.
By Mariana Araguaia
Graduated in Biology
Source: Brazil School - https://brasilescola.uol.com.br/doencas/esquistossomose.htm