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Swimmer's Itch

Swimmer’s itch is a skin condition caused when swimming larvae of several species of parasitic flatworms encounter human beings rather than their usual avian host, penetrate the skin and trigger an allergic reaction in many people. Scientifically known as schistosome cercarial dermatitis, it has been recognized in Michigan inland lakes since at least the 1920s, although only in recent years has it become a significant problem for recreation.

In response to increasing complaints on Crystal Lake, the CLWA formed a Swimmer’s Itch committee in the summer of 2006. In 2009 concerned stakeholders formed the Crystal Lake Swimmer’s Itch Partnership, which now constitutes one of the standing committees of the CLWA. In 2015, CLWA helped form a coalition called Michigan Swimmer’s Itch Partnership (MISIP), now consisting of 24 northern Michigan lake associations. By joining forces the group has greatly expanded the expertise and resources now being directed at solving this complex problem, which is so detrimental to enjoyment of Crystal Lake’s waters.

During the summer of 2016 the CLWA contracted with SICON LLC to carry out a full-lake assessment of the snail infection rate on Crystal Lake, which will serve as a base-line metric for measuring future progress in decreasing the incidence of the parasite. TO READ THEIR REPORT CLICK HERE.

In 2017, with the assistance of a grant from the State of Michigan awarded to the MISIP, the CLWA hired Swimmer’s Itch Solutions LLC to trap merganser broods and relocate them to other water bodies where swimmer’s itch is not present. Higgins Lake has experienced excellent results from a similar program that began three years ago, so we expect to see promising results as soon as 2018. A full report on this work is now available HERE.

Over the years the CLWA has developed several trial programs to combat swimmer’s itch:

  • Pyrotechnics to discourage common mergansers, which carry the parasite, from nesting on Crystal Lake in the spring;
  • Raking the lakebed to disrupt parasite-infested snails dwelling in swimming areas during the summer;
  • Hunting to decrease the merganser population in the fall;
  • Public education, including a brochure on preventing and treating swimmer’s itch, signs at major public beaches, public meetings and media outreach;
  • Product testing to find effective barriers that can be applied to protect the human body.

In addition, the CLWA actively supports scientific research to increase knowledge of the biology of the parasitic cycle and the causes of swimmer’s itch, in order to find better methods of combating it. Daily records maintained at the Congregational Assembly beach have provided invaluable raw data. See the data here: Swimmer’s Itch data CSA summary 2013-2017