A dermatitis of unknowns etiology has occurred among the farmers working in paddy fields in some districts of Kagoshima Prefecture, such as Ibusuki, Hiyoshi, Oura, Makizono and Minami-tane.
In order to acertain the cause of the disease, the epidemiological investigations have been made since1975.
The dermatitis occurrs from March to July when rice-planting and weeding are on and is characterized by erythemato- papulo-vesicular eruptions accompanied with severe itching. The chief symptoms are observed on the parts exposed to water, especially on forearms and lower legs.
The research for snail intermediate hosts was carried out in the paddy fields where the dermatitis originated.
As a result, two species of apharyngeal furcocercous cercariae were obtained from the fresh water snails, Polypylis hemisphaerula and Austropeplea ollula. The cercaria from P. hemisphaerula resembled to that of Gigantobilharzia sturniae in shape and size, and the other one from A. ollula was identified as species belonging to the genus Trichobilharzia and was regarded the same species as described in Saitama Prefecture by the authors.
An experimental infection with the cercaria belonging to the genus Trichobilharzia was performed. A few drops of water containing10cercariae were placed on the forearm. The cercariae invaded into the skin and produced a dermatitis quite similar to that prevailing in the endemic areas.
Therefore, it was concluded that the etiological agent were the cercariae of two different avian schistosomes, namely, G. sturniae and Trichobilharzia sp.