09-28-1988 - Agenda Packet City Council - regular meeting

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Swimmer's itch: a preventive approach A baby merganser (raving its toenails clipped before treatment with Praziquantel. And below, a cercaria that can penetrate the skin and cause swimmer's itch. The research at Glen Lake centered around use of the drug Praziquantel on infected aquatic birds as an alternative to treating lakes with copper sulfate, the traditional remedy for swimmer's itch. Copper sulfate kills the intermediate snail host, breaking the life cycle of the parasite and theoreti- cally reducing or eliminating the problem. However, this method has several drawbacks. While copper sulfate can indeed kill snails, it is a very toxic sub- stance that can be lethal to most forms of life. Moreover, its effectiveness depends on prolonged, uniform application, exposing snails for several hours. Unfortunately, wave action, changing wind direction, water pH, application method and the knowledge and experience of the applicators are all variables that can drastically reduce the chemical's effectiveness. In addition, scientific assumptions that copper sulfate does not harm the environment are proving incorrect. No long-term studies have been done on the effects of copper in lake sedi- ments on aquatic organisms, but data from short-term studies indicate a higher ratio of adverse affects on animals than was previ,)usly thought. This discovery is prompting resi- derrts on some lakes to threaten litigation if copper sulfate is aF died. Without an adequate remedy for swimmer's itch, some lake -domi- nated statU such as Michigan, are experienciri , increases in the occur- rence and severity of this disease. This may be due to a combination of factors, includ- ing more awareness and reporting of swimmer's itch increased recreational use of lakes, and more aquatic birds In addition, improved water quality on many lakes has raised populations of aquatic or- ganisms such as snails However, the Glen Lake studies indicate that Praziquantel treatments may solve the copper sulfate dilemma. This method treats the infected birds instead of the lake Since . & to. the majority of the infected birds are not migratory, treatments should break the parasite's life cycle. Seed -eating birds, such as mallards, Canada geese, swans and wood ducks, are prebaited and then given Praziquantel in feedings of grain or grain products. Non -seed -eating birds, such as the common mer- ganser, are captured and either injected or given an oral dose of the drug. They are then aged, sexed and released on a lake where the snail host is not found or where swimming is not a major recreational activity. Laboratory studies with mallard ducks found Praziquantel to be non -toxic (even at 50 times the nor- mal dose) to birds or to other aquatic: animals. Further research indicated that treating 50 to 75 birds with the drug costs less than an ap- plication of copper sulfate at current levels. During the past three years, in- fection in both snails and ducks has declined substantially following Praziquantel treatment. Many resort owners at Glen Lake reported fewer incidences of swimmer's itch during the past two years, and none reported an ircrease While much more work must be done before this method's potential can be fully evaluated, re- searchers at Glen Lake are very encouraged with the initial phase Ultimately, this could mean good news for tourists as well as for the economies of those lake areas that depend upon tourist -generated income LAKE LINE, September P88 Page 5 I