Paddy field dermatitis in Assam: a cercarial dermatitis.

Rice field dermatitis is an occupational health problem in Assam. The afflicted paddy field workers develop exanthema on the exposed parts of their skin mainly legs and arms when they come in contact with water in rice fields. Itching sensations start after 30 minutes to 1 1/2 hours after initial exposure. After 6-12 hours there is intensely pruritic macular eruption and in a few cases secondary skin infection may also develop. The clinical course of the disease is suggestive of cercarial dermatitis. Numerous gastropod snails belonging to families Lymnaeidae, Bulinidae and Planorbidae were collected from paddy fields and were investigated for cercarial infection. It was found that planorbid snails were infected with animal schistosome cercariae. These cercariae were able to invade human skin and caused dermatitis in human volunteers after repeated exposure.