An epidemic of dermatitis of unknown etiology occurred from May to August, 1983 among the farmers working in paddy fields in Kusatsu city, Shiga prefecture.
The dermatitis was characterized by erythemato-papulo-vesicular eruptions with severe itiching, and localized in legs and arms.
The questionnaire was conducted on 1757 farmers, and 192 of them replied that theysuffered from dermatitis after working in paddy fields with shoes or bare feet. Among the farmers suffering from dermatitis, 58.1 % of them were suspicious of cercarial dermatitis. And the inquiry by the phone made it more affirmative that 90 % of the dermatitis were cercarial dermatitis.
Six patients were serologically examined by indirect fluorescent antibody method using Gigantobilharzia cercariae and Schistosoma mansoni cercariae as antigen. All of them showed high serum titer, and were diagnosed as cercarial dermatitis. Although no cercariae was found from snails in paddy fields of Kusatsu city, Austropeplea ollula, the vector snail for avian schistosome especially for Trichobilharzia was the extremely dominant snail (99.3 %). Trichobilharzia was the most suspicious avian schistosoma as the etiology of this epidemic dermatitis in Kusatsu area.

There is a great diversity of manner in agricultural daily work compared to other industrial works. Therefore, at the estimation and comparison of farmers' subjective symptoms caused by the work, it should be known the relative grade of the work load of the day compared to those of other working days.
From this viewpoint, in this study, seventy three farmers who had been surveyed the subjective symptoms after daily work 10-16 months before were shown the working record of the day and were made to recall and estimate the grade of the work load and fatigue at that time by five steps rating method. The obtained data were referred to their fatigue symptoms.