Swimmer's Itch - Treatment and Prevention
Schistosomes are parasites, also known as flukes or flatworms, whose primary hosts are ducks. Schistosomal dermatitis, or "swimmer's itch" or "clam digger's itch" is a rash which results when the larval stage, or cercariae, of these parasites penetrates the skin of a human, perhaps in the course of seeking a freshwater snail as its host.
This problem is not always limited to freshwater lakes and rivers. In the United States, the states surrounding the Great Lakes have the highest occurrence, but the far south, Pacific northwest, and plains states also have had outbreaks. The snails that harbor the larvae inhabit the same type of lake waters that bathers prefer, and are not abundant in rough waters. The larvae are normally released in warm water, with July the peak month.
The development of the rash depends on previous exposure and individual allergy to the larvae. After the first exposure, bumps may appear five to thirteen days later. Re-exposure produces reactions that are increasingly more rapid and intense because of the heightened allergic response. After sensitization develops, the rash typically begins one or two days after exposure with small, itchy bumps. There may be a prickling sensation as the victim leaves the water, due to the cercariae penetrating the skin. This sensation can be felt for an hour or so, as the water evaporates from the skin. The bumps may appear as soon as ten hours later. They are surrounded by a red area and sometimes develop small blisters on top of each bump. In severe reactions, the bumps coalesce to form large, red swollen areas. The rash resolves in a few days, but secondary infection is common.
Swimmer's Itch - Treatment
Rubbing alcohol, calamine, or soothing creams or lotions can be applied to the rash for symptomatic treatment. Antihistamines help relieve itching. Aspirin may be helpful. The most practical preventive is rough toweling and showering.
Swimmer's Itch - Prevention
Duck hunters and fishermen may be involved as well as swimmers and bathers. A layer of thick grease applied to the skin or the wearing of tightly woven clothing may deny the larvae access to the skin, but this is impractical for bathers. Swimmer's itch can best be prevented by destroying the snails, through chemical treatment, that serve as hosts for the larvae.
This problem is not always limited to freshwater lakes and rivers. In the United States, the states surrounding the Great Lakes have the highest occurrence, but the far south, Pacific northwest, and plains states also have had outbreaks. The snails that harbor the larvae inhabit the same type of lake waters that bathers prefer, and are not abundant in rough waters. The larvae are normally released in warm water, with July the peak month.
The development of the rash depends on previous exposure and individual allergy to the larvae. After the first exposure, bumps may appear five to thirteen days later. Re-exposure produces reactions that are increasingly more rapid and intense because of the heightened allergic response. After sensitization develops, the rash typically begins one or two days after exposure with small, itchy bumps. There may be a prickling sensation as the victim leaves the water, due to the cercariae penetrating the skin. This sensation can be felt for an hour or so, as the water evaporates from the skin. The bumps may appear as soon as ten hours later. They are surrounded by a red area and sometimes develop small blisters on top of each bump. In severe reactions, the bumps coalesce to form large, red swollen areas. The rash resolves in a few days, but secondary infection is common.
Swimmer's Itch - Treatment
Rubbing alcohol, calamine, or soothing creams or lotions can be applied to the rash for symptomatic treatment. Antihistamines help relieve itching. Aspirin may be helpful. The most practical preventive is rough toweling and showering.
Swimmer's Itch - Prevention
Duck hunters and fishermen may be involved as well as swimmers and bathers. A layer of thick grease applied to the skin or the wearing of tightly woven clothing may deny the larvae access to the skin, but this is impractical for bathers. Swimmer's itch can best be prevented by destroying the snails, through chemical treatment, that serve as hosts for the larvae.
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