Evaluation of targeted copper sulfate (CuSO4) application for controlling swimmer’s itch at a freshwater recreation site in Michigan


Swimmer’s itch has historically been controlled by applying copper sulfate (CuSO4) to lakes as a way to eliminate snails that serve as the intermediate hosts for swimmer’s itch-causing parasites. CuSO4 is still sometimes applied specifically to areas of lakes where swimmer’s itch severity is high. It is unclear whether targeted application of chemical molluscicides like CuSO4 is effective for controlling swimmer’s itch. Previous research has found that the larval stage of the parasites responsible for swimmer’s itch are released from infected snails and are concentrated by onshore and alongshore winds, and thus, may not be affected by such focused applications. In this study, we evaluated the impact of targeted CuSO4 application to a specific recreational swimming area in a lake in Michigan. We measured the effect on snail populations, as well as on the presence/abundance of swimmer’s itch-causing parasites using qPCR. Ultimately, while CuSO4 was confirmed to significantly reduce populations of snails within the treatment area, it was found to have no significant impact on swimmer’s itch-causing parasites in the water, likely due to the free-swimming larval stages (cercariae) moving into the treatment area from surrounding regions.

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This work was supported by the Michigan Swimmer’s Itch Partnership (RLR), Alberta Environment – Energy and Environment Solutions #2332 (PCH) and the Natural Sciences and Engineering Council of Canada #2018-05209 and 2018-522661 (PCH).

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Correspondence to Patrick C. Hanington.

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Froelich, K.L., Reimink, R.L., Rudko, S.P. et al. Evaluation of targeted copper sulfate (CuSO4) application for controlling swimmer’s itch at a freshwater recreation site in Michigan. Parasitol Res 118, 1673–1677 (2019). https://doi.org/10.1007/s00436-019-06280-3

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  • Swimmer’s itch
  • Digenetic trematode
  • Schistosome
  • qPCR
  • Water
  • Copper sulfate
  • Chemical treatment