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Chapter 2

Schistosomiasis

Schistosomiasis is one of the most protean diseases suffered by man. It was known to the Pharaohs over 5,000 years ago. The presence of species of snails in Paleolithic sites in Africa, capable of carrying the immature stages of the parasite raises the possibility of an even older history. The ancient Egyptians recognized the malady causing "the bloody urine and stools" and knew that it was caused by worms. It now infects about 200 million people throughout the tropical world and its literature is vast and complex, describing many aspects of the disease in many languages. Bilharz first described the etiology in 1851, but it was not until 1913 that Myairi recognized the snail as the intermediate host. It was many years later, in 1957, that schistosomiasis was first described in Southeast Asia. The Mekongi subspecies was not accepted until 1978. It is truly a continuing modern plague, yet the life cycle of this blood fluke is such that the adoption of simple but strict hygiene would probably eradicate the disease within a generation. Surveying the subject, one must wonder both at man's failure to rid himself of this affliction and at his ability to live with it.

Synonyms

Schistosomiasis: Bilharzia. Bilharziasis. Katayama disease. Kin Kiang fever. Egyptian splenomegaly. Cercarial dermatitis. Swimmer's itch. Collector's itch. Dew itch. Sawah itch. Snail fever. Yangtze fever. Koganbyo. Clam digger's itch. Kichocho. Haemic distomiasis.

Schistosomiasis haematobium: Sp: Esquistosomiasis urinaria. Hematuria de Egypto. Hematuria de los paisos calidos. Fr: Schistosomiase urinaire. Bilharziose. Hematurie du Cap. Ger: Blasenbilharziose.

Schistosomiasis mansoni: Sp: Esquistosomiasis intestinal. Fr: Schistosomiase intestinale. Ger: Darmbilharziose.

Schistosomiasis japonica: Sp: Esquistosomiasis japonesa. Fr: Schistosomiase japonaise. Ger: Schistosomiasis japonica.

Definition

Schistosomiasis is an infection with parasitic blood flukes (worms) which are digenetic trematodes, schistosomatidae. Four species regularly affect man: S. haematobium, S. mansoni, S. japonicum and S. intercalatum. Four more have limited geographical distribution; S. mattheei, S. mekongi, S. incognitum, and S. rodhaini. Within these species there are some strains, such as the Formosan strain of S. japonicum, which live for only a short period within man and may fail to reach maturity. There are other species, normally parasites of cattle or birds (zoonotic) which also occasionally infect man but do not usually cause significant symptoms or radiological changes. However, they can confuse laboratory tests. When they do rarely cause symptoms, the illness is less severe.

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Copyright: Palmer and Reeder