Larval trematodes in freshwater snails at the Ross River Reservoir, northern Australia, with emphasis on Trichobilharzia sp(p)., causative agents of swimmer's itch

Abstract

Prevalence of trematode cercariae within freshwater snails at the Ross River reservoir is presented, with special attention to Trichobilharzia sp(p). (Digenea:Schistosomatidae), known causative agents of schistosome dermatitis. Three pulmonate snails-a lymnaeid, Austropeplea lessoni, and two planorbids, Gyraulus gilberti and Amerianna carinata-and one prosobranch snail, Thiara balonnensis, were common in the reservoir. These snails were infected with trematode cercariae representing six different families. Both Austropeplea lessoni (4.5%) and G. gilberti (1.8%) act as intermediate hosts of Trichobilharzia sp(p). Trematode infection levels increased as snail size increased. The implication for surveillance techniques is that only the larger snails (A. lessoni > 10 mm, G. gilberti > 3 mm and Amerianna carinata >6 mm) require dissection to determine the prevalence of trematode infections.