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Epidemiology

Many types of schitosome species cause cercarial dermatitis, therefore the distribution of the disease is world-wide. Often times the distribution of the schitosome mirrors the distribution of its intermediate host, the snail. The following table summarizes the distribution of various types of schistosomes: There are two basic types of human activities that lead to exposure to cercarial dermatitis. The first are recreational activities such as swimming and diving bring people in contact with avian or mammalian cercariae. Secondly, farming or food production that requires flooded fields such as rice farming. While the first may be an unfortunate nuisance for fun-loving beach goers, the second activity is necessary for subsistence and economic well-being. For example, for workers in the water chest nut industry in India cercarial dermatitis is a serious problem, especially for the veteran workers that have been exposed multiple times. As one may recall, the immune response becomes more vigorous with subsequent exposures.

Overview of World Distribution of Schistosomes Causing Cercarial Dermatitis

Genus Location Intermediate Host Final Host
Schistosomatinae
Heterobilharzia North America Pulmonata Mammals
Orientbilharzia Asia Pulmonata Mammals
Schistosoma Worldwide Pulmonata,
Prosobranchia		 Mammals
Schistosomatium North America Pulmonata Rodents
Austrobilharzia Worldwide Prosobrachia Birds
Bilharzienllinae
Bilharziella Northern Hemisphere Pulmonata Birds
Trichobilharzia Worldwide Pulmonata Birds
Gigantobilharziinae
Gigantobilharzia Worldwide Opsithobrachia Birds



Country Information

Has a worldwide distribution. Although the type of activity that leads to exposure can be guessed. It can also be inferred that cercarial dermatitis will present more of a public health issue in areas where exposure to water is a vital part of economic activities. For example, countries that rely on flooded-field farming and tourism centered around aquatic activities may consider cercarial dermatitis more of a problem than others.