VIII.124 - Schistosomiasis

Summary

Schistosomiasis (bilharzia), known also by many local names such as “red-water fever,” “snail fever,” “big-belly,”and “Katayama disease,”is an “mmunologic disease”induced by eggs of blood-vesselinhabiting worms of the class Trematoda, genus Schistosoma. These eggs induce an immunologic response after they become trapped in the body organs, especially the liver, gut wall, and urogenital tract.

There are three major human schistosome species: Schistosoma haematobium, which inhabit the veins of the bladder area and whose eggs are discharged in the urine; and Schistosoma mansoni and Schistosoma japonicum, which inhabit the mesenteric veins supplying the intestines and whose eggs are discharged in the feces. In every case, however, the worms may also be found in the liver and portal system. There are also a few other species that can parasitize humans. These include the japonicum-like Schistosoma mekongi from the lower Mekong River basin, and some African schistosomes, such as Schistosoma intercalatum, that normally parasitize cattle and wild animals.

Terminology

The terminology of this disease is very confusing. Theodor Bilharz, the discoverer of the trematode worm responsible for the disease, placed it in the genus Distoma, a broad genus that was soon abandoned as more trematode species were discovered. Numerous generic names were thereafter invented to label the worm, including Schistosoma in 1858 (the name that must stand according to the rules of zoological nomenclature), Gynaecophorus in 1858 Bilharzia in 1859, and Thecosoma in 1860. Before World War II, however, in an understandable desire to honor the name of Bilharz, the disease was commonly called bilharziasis.