Recent Discoveries

The Ineffectiveness of Using Copper Sulfate for Sustained Control of Swimmer’s Itch

Our research showed that itch-causing parasite cercariae drift considerably, which renders the environmentally damaging practice of applying tons of copper sulfate to kill snails in a swim area ineffective. This important research was instrumental in causing policy change in Michigan, thus further protecting our recreational waters.

2019 - Froelich, K.L., Reimink, R.L., Rudko, S.P., VanKempen, A.P., and Hanington, P.C. Evaluating the efficacy of molluscicide copper sulfate (CuSO4) at reducing cercariae concentrations at a recreation site in Michigan. Parasitology Research 118(5):1673-1677. 

A New Schistosome Species Capable of Causing Swimmer’s Itch

Our non-biased approach to analyzing the causes of swimmer’s itch in Michigan led to the discovery of a new species of parasite from a genus of snail never known to serve as a suitable host in North America. We have since discovered this new species is very common in Michigan, often dominating the schistosome parasite community in lakes.

2021 - Brooke A. McPhail, Sydney P. Rudko, Alyssa Turnbull, Michelle A. Gordy, Ronald L. Reimink, Daniel Clyde, Kelsey Froelich, Sara V. Brant, Patrick C. Hanington. Evidence of a putative novel species of avian schistosome infecting Planorbella trivolvis.Journal of Parasitology 107(1):89-97 (2021)

Non-resident Waterfowl Sustain High Levels of Itch-causing Parasites in Many Lakes

This landmark research produced data that showed removing summer resident waterfowl from our study lakes did not reduce the parasite load to acceptable levels. 

2022 - Rudko, S.P., McPhail, B.A., Reimink, R.L., Froelich, K., Turnbull, A., Hanington, P.C. Non-resident definitive host presence is sufficient to sustain avian schistosome populations. International Journal of Parasitology, January 2022 (https://www.sciencedirect.com/science/article/pii/S0020751922000017?v=s5)

Swimmer’s Itch is Now Preventable

Due to improved technologies, we made more discoveries these past 5 years than the previous 40 years, which has shifted the swimmer’s itch paradigm from control to prevention. This has allowed many lake associations to channel limited funds away from expensive duck trapping towards more pressing lake preservation issues. Besides economics, this paradigm shift has other important advantages over lake-wide control methods: 1. The fragile lake ecosystem is not disturbed by completely removing a top-tier predator and a significant zooplankton contributor, 2. Association funds can be spent on issues affecting all members as opposed to just 30% of the people who actually get swimmer’s itch, 3. Bird lovers can enjoy watching the waterfowl all summer long, 4. Individual riparians now have control of their risk of getting swimmer’s itch and don’t have to wonder if a swim will result in a ruined vacation. 

Education is an important part of this paradigm shift. Here are some things we’ve discovered and documented through our publications:

1. Itch-causing cercariae are more prevalent in the morning and drop off drastically later in the afternoon (they only live for a day, are eaten by other zooplankton, and/or are blown up on shore with wind).

2. Cercariae rise to the water’s surface once released from the snails early in the morning and then move about by the wind and water currents.

3. Cercariae can be prevented from entering a swim area using a simple floating baffle.

4. Cercariae can be easily removed from a swim area using a fine mesh (20um) net.

5. Tight-fitting protective swimwear (such as rash guards used by ocean swimmers to prevent jellyfish stings) can be worn for protection

6. Cercariae density increases with an onshore wind (they get blown into a swim area) but decreases with onshore wind intensity. This is thought to be because stronger winds more quickly blow the cercariae up on shore (unless, of course, there is a sea wall in which case they will likely congregate in shallow water). Therefore, be cautious letting children play in the first few feet of water nearest to shore when there is an onshore wind (unless they are protected).