RESUMO
A dermatitis of unknown etiology has occurred among farmers working in paddy fields in the eastern area of Saitama Prefecture (Ozu et al., 1972). And it was proved to be caused by the invasion of a bird schistosome cercaria shed from <I>Austropeplea ollula</I> (Suzuki et al., 1973).<BR>In an attempt to dertermine the final host of this schistosome, a survey on the wild birds was undertaken in the endemic area. But, no natural infection was found in 8 Corvus corone, 7 <I>Sturnus cineraceous</I>, 5 <I>Egretta garzetta</I>, 4 <I>Nycticorax nycticorax</I>, 8<I>Anas platyrhynchos</I>, 7 <I>A. crecca</I> and 170 <I>A. poecilorhyncha</I>.<BR>Experimental infections with the cercariae were performed using domestic ducklings and canaries, and a bird schistosome egg could be found in feces of the domestic ducklings 20 days after the infection. The egg was crescent-shaped and the miracidium was clearly seen within.<BR>Based on the results of the experimental infections, the most probable final host of this schistosome in Saitama Prefecture was supposed to be the anatid birds.