Verbrugge, L.M., J.J. Rainey, R.L. Reimink, and H.D. Blankespoor. 2004. Prospective study of swimmer’s itch incidence and severity. Journal of Parasitology 90(4): 697-704.

 This epidemiologic study reports incidence, severity, and risk factors of swimmer’s itch (cercarial dermatitis). Daily diaries about water exposures and swimmer’s itch symptoms were completed by 40 riparian households at Douglas Lake, Michigan, for July 2000. Minutes spent in the water, minutes in shallow water, location, time of day, preventive action, age, and gender were recorded for all residents and guests. Incidence of swimmer’s itch was 6.8 episodes per 100 water-exposure days. Probability of an episode increased with more days of water use and at locations with onshore winds. Episode severity increased with more time in the water and at the same locations. Age and gender had no effect on incidence or severity. In sum, onset and severity of swimmer’s itch are affected by how people interact with the lake, not by their demographic features. More studies of human incidence and severity are needed to convince public health agencies to address this problem at recreational lakes. Study designs that combine epidemiologic and biological data will simultaneously inform public health education and biological control programs.

Verbrugge, L.M., J.J. Rainey, R.L. Reimink, and H.D. Blankespoor. 2004. Swimmer’s Itch: Incidence and Risk Factors. American Journal of Public Health 94(5): 738-741.

Swimmer’s itch (cercarial dermatitis) affects people engaged in open-water activities. We report incidence and risk factors for a US lake. Water exposures and swimmer’s itch experience were reported daily for riparian household residents and guests at Douglas Lake, Michigan, in July 2000. Incidence of swimmer’s itch was 6.8 episodes per 100 water exposure days. Positive risks were (1) exposures in shallow water and in areas with onshore winds and (2) more days of lake use in July. Further epidemiological studies will help public health agencies address this bothersome problem at recreational lakes.

Blankespoor, C.L., R. L. Reimink, and H.D. Blankespoor. 2001. Efficacy of Praziquantel in Treating Natural Schistosome Infections in Common Mergansers. Journal of Parasitology 87: 424-426. 

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. 

Blankespoor, H.D. and R. L. Reimink. 1998. An Apparatus for Individually Isolating Large Numbers of Snails. Journal of Parasitology 84(1): 165-167.

An apparatus for rapid screening of large numbers of snails for cercariae of digenetic trematodes is described. Snails are placed in special plastic vials suspended in Lexan inserts, exposed to fluorescent light in a wooden cabinet, and then examined in a special aluminum tray designed for use with a dissecting microscope.

Reimink, R.L., J. A. DeGoede, and H.D. Blankespoor. 1995. Efficacy of Praziquantel in Natural Populations of Mallards Infected with Avian Schistosomes. Journal of Parasitology 81(6): 1027-1029.

In 1991, mallards (Anas platyrhynchos) on North and South Lake Leelanau in Leelanau Co., Michigan were trapped, examined for
natural infections of avian schistosomes, and treated with praziquantel.
Prevalence of infection from the 113 birds recaptured in 1992 was
compared with that of the previous year on these 2 inland lakes after some of the birds were treated. Infections were determined by examining diluted fecal samples for hatched schistosome miracidia. Approximately  15% of the 366 birds captured the first year homed the second and made up about 27% of the resident mallard population. Of the birds treated
in 1991, only 1.8%showed an infection in 1992 compared with 14.6% for previously untreated birds.  These data indicate that praziquantel is
an effective therapeutic agent for reducing natural infections of the parasite in mallards. Furthermore yearly treatment of mallards at specific Michigan sites may not be necessary for effective control of swimmer’s itch on North and South Lake Leelanau.

Blankespoor, H.D. and R. L. Reimink. 1991. The Control of Swimmer’s Itch in Michigan: Past, Present, and Future. Michigan Academician 24: 7-23. 

 The association between a type of dermatitis known as swimmer’s itch and the free-living stage of certain digenetic trematodes (nonhuman schistosomes) was delineated in 1928 by Cort at the University of Michigan Biological Station. Following his discovery, studies on swimmer’s itch have continued at the Biological Station until the present time. In 1939, the State of Michigan initiated a control program that included the application of copper sulfate to many of the larger recreational lakes. It was assumed that this molluscicide would reduce the prevalence and incidence of swimmer’s itch by interrupting the life cycle of the parasite in the snail intermediate hosts. Unfortunately, swimmer’s itch continues to be a problem in Michigan despite more than a half century of control efforts. In addition, concerns about the accumulation of toxic copper sulfate in our aquatic ecosystems are being expressed more frequently. In 1985, Blankespoor initiated a new approach to the control of swimmer’s itch by treating the definitive host with an antihelminthic drug, Praziquantel. Based on four years of research on Glen Lake, the authors have concluded that controlling swimmer’s itch with Praziquantel is more effective than using copper sulfate, less expensive, and has no detrimental effects on the environment. In 1990, the program was expanded to include three additional lakes in Leelanau County, Michigan.

Guth, B.D., H.D. Blankespoor, R. L. Reimink, and W.C. Johnson. 1979. Prevalence of Dermatitis-Producing Schistosomes in Natural Bird Populations of Lower Michigan. Proceedings of the Helminthological Society of Washington 46(1): 48-53.