Experimental Infection of Several Lymnaeid Snails with Heterobilharzia americana

Abstract

Heterobilharziasis seems to have a limited geographic range restricted to the coastal lands of the Gulf of Mexico and the Carolinas. Its snail hosts in this region are the lymnaeids Fossaria cubensis and Pseudosuccinea columella. In the present study seven species of lymnaeid snails from out- side the known zone of distribution of heterobilharziasis (a total of 10 regions in the United States and other parts of the Americas) were exposed to the miracidia of this schistosome. Results of the sus- ceptibility tests show that the geographical range of susceptible snail hosts far exceeds that of H. americana. Its restricted distribution cannot be explained adequately on the basis of the absence of susceptible snail hosts in areas where it has not been reported. Heterobilharzia americana, a schistosome of the raccoon, dog, bobcat, nutria, marsh rabbit, and other mammals, is prevalent in the coastal lands of Texas, Louisiana, Florida, and North Carolina (Malek et al., 1961). Recently it has been found in deer in South Carolina (Byrd, pers. comm). It has not been reported from other parts of North, Central, or South Amer- ica. The mollusks serving as larval hosts to this schistosome are the lymnaeid snails Fos- saria cubensis and Pseudosuccinea columella.