Efficacy of Praziquantel in Treating Natural Schistosome Infections in Common Mergansers

Abstract

Fifty-one common mergansers were captured on Douglas Lake (Cheboygan County, Michigan) and their avian schistosome loads were determined by fecal examination. Each bird was given a single dose of 0, 40, or 200 mg/kg of body weight of praziquantel and released. All birds were recaptured within 10 days of drug administration to determine posttreatment schistosome loads. Only the highest dose of praziquantel was found to significantly reduce avian schistosome loads. The potential use of praziquantel in swimmer's itch control programs is discussed.

Molecular Systematics of the Avian Schistosome Genus Trichobilharzia (Trematoda: Schistosomatidae) in North America

“…Although other duck species are also infected, prevalence is very low or there were few worms, most immature (Table II). One of the principal hosts of T. stagnicolae is a merganser (Blankespoor and Reimink, 1988; Leighton et al, 2000; Blankespoor et al, 2001; Coady et al, 2006), corroborated by our survey. It is interesting to note that 2 of the 3 unidentified lineages in Clade Q came from Anas americana , the American widgeon.…”

“…In our study, we collected miracidia from mergansers, Mergus merganser, from the type locality, Douglas Lake, but were unable to locate adult worms or eggs. Our assignment of the name T. stagnicolae to the samples we collected was justified based on the following: 1) our samples were collected from the type locality and the type snail; 2) we infected successfully the type snail with miracidia collected from the type locality; 3) our cercarial measurements were the same as those reported by Talbot (1936) and McMullen and Beaver (1945); 4) previous fecal examinations of M. merganser on Douglas Lake revealed eggs of T. stagnicolae (Blankespoor et al, 2001); and 5) our collections of cercariae from S. emarginata from several lakes in northern Michigan, in northern Minnesota, and New Mexico (Table III), all genetically matched what we collected at Douglas Lake, the type locality (0%–1.2% for cox 1). The finding of a distinct genetic lineage with widespread representation strongly suggests our samples are T. stagnicolae .…”

“…McMullen and Beaver (1945) described T. stagnicolae from an experimental infection in canaries; their study is the only description and record of T. stagnicolae adults. Subsequent reports of presumptive T. stagnicolae in the literature have been as cercariae from S. emarginata (Swales, 1936; McLeod, 1940; Elliott, 1942; Zischke and Zischke, 1968; Keas and Blankespoor, 1997; Leighton et al, 2000; Blankespoor et al, 2001; Coady et al, 2006). In our study, we collected miracidia from mergansers, Mergus merganser, from the type locality, Douglas Lake, but were unable to locate adult worms or eggs.…”

“…Although most North American outbreaks of cercarial dermatitis are ascribed to T. physellae or T. stagnicolae (Swales, 1936; Cort, 1950; McMullen and Brackett, 1941; McLeod, 1940; Hunter, 1960; Zischke and Zischke, 1968; Leighton et al, 2000; Blankespoor et al, 2001; Coady et al, 2006), such identifications typically reflect whether the cercariae were shed from a physid or lymnaeid snail, respectively. The framework incorporating molecular markers developed here will be of immediate use in making more precise determinations.…”

A study on cercarial dermatitis in Khuzestan province, south western Iran

“…Control of this condition is difficult, requiring strict maintenance of bodies of water and if necessary the use of molluscicides such as niclosamide. The use of praziquantel in baits for treating the definitive hosts appears to interrupt the natural cycle of avian schistosomatidae [12]. …”