Swimmers Itch - Some Maine Lakes have a serious problem with swimmers itch. Swimmers itch is a skin rash caused by a parasite that infects some birds, ducks, geese, swans, and other small mammals. These parasites migrate through water and are capable of penetrating human skin and can cause an allergic reaction. About one third of the people who come in contact with the parasite develop swimmers itch. Children are most often infected because they swim or wade in shallow water. Symptoms may appear within one to two hours of exposure. The irritated spot reaches its maximum size after 24 hours. The itching may continue for several days. The symptoms should disappear within a week. There is no treatment necessary for swimmers itch. It is recommended that people do not feed ducks (and in the case of Dexter's public beach, the seagulls) in order to prevent this problem from occurring.