A parasite of birds and mammals that is released by infected snails into natural bodies of water, including those used for recreational swimming. Schistosomes can cause a skin rash that is also called schistosome dermatitis, or “swimmer’s itch,” and often affects children. The skin irritation is acquired by swimming or wading in water infested with schistosomes and then allowing the water to evaporate from the skin, rather than using a towel to dry the skin. As the water evaporates from the skin, a tingling sensation may be experienced as the schistosome parasite penetrates into the skin. This mild itching generally subsides within 10 to 15 hours and then resumes as an extremely intense itch, which may persist for a week. Initial exposure to infested water may not cause schistosome dermatitis, but repeated episodes of exposure thereafter increase sensitivity to the parasite. The rash is treated with creams and lotions containing specific antiparasite ingredients.