Five New Species of Avian Schistosomes from Wisconsin and Michigan with the Life Cycle of Gigantobilharzia gyrauli (Brackett, 1940)

Abstract

In a recent summary of the distribution of schistosome dermatitis in this country (Brackett, 1941), it was reported that the disease is to be found chiefly in the northern parts of Michigan, Wisconsin, Minnesota, and Manitoba. In this area, Cercaria stagnicolae Talbot, 1936, is responsible for the largest proportion of the outbreaks. This can partially be explained by the fact that its snail hosts, varieties of Stagnicola emarginata, prefer a habitat that is also chosen by bathers and that this snail species reaches the height of its development during the resorting season. Within this important center of schistosome dermatitis, the disease was found to be distributed unequally and to fluctuate from year to year. Neither of these features could be completely correlated with the presence or absence or fluctuations of the snail hosts and it was suggested that the explanation probably would be found when the life cycle of C. stagnicolae is demonstrated and the adult stage and its host become known. Talbot (1936) and others have attempted to determine the life cycle of C. stagnicolae by exposing birds and mammals to this form. Perhaps these experiments have all been unsuccessful because this cercaria may be very specific in its definitive host and the proper bird or mammal might not have been used. In an effort to become better acquainted with the adult schistosome fauna of the dermatitis areas McLeod (1940) and the author (Brackett, 1940a) and others have examined many birds and some mammals from Manitoba, Wisconsin, and Michigan specifically for blood flukes. The results of these investigations combined with reports in the literature showed that about 10 species of schistosomes occurred in birds to be found in Wisconsin and vicinity. The present paper reports the results of the examination of birds in the spring and summer of 1940 in Wisconsin and Michigan during which time 5 previously undescribed schistosomes were found.