The Species Composition of the Definitive Hosts of the Trematode Bilharziella polonica (Schistosomatidae) of Southern Karelia (Northwestern Russia)

A helminth fauna study of 398 waterfowl specimens belonging to 43 species living in southern Karelia wetlands (northwestern Russia) was conducted. This is the first time when data on the species composition and the infection of birds that are definitive hosts of Bilharziella polonica Schistosomatidae have been obtained. Bilharziella polonica has been recorded only in seven bird species, namely in the mallard, the Eurasia-n teal, the common goldeneye, the tufted duck, the northern shoveler, and the red-necked grebe; the infestation of the latter is noted in northwestern Russia for the first time. Of the bird species examined, this study describes the role of trematoda-infected birds in maintaining the focus of cercariosis, also known as “swimmer’s itch,” a disease pathogenic for humans. The data presented in our study indicates that the tremat-ode development cycle occurs successfully in the environment of Karelia.