Welts normally disappear within a week but red coloration may persist some time longer. The inflamed areas resemble chigger bites, but differ in distribution on the body. Chiggers tend to attack the legs, groin, waistline, and underarm areas, whereas swimmers' itch can be distributed over any exposed area of the body. Swimmers' itch does not produce watery blisters like poison ivy, does not spread from the point of penetration of the parasite, and is not contagious like bacterial infections. Outbreaks of swimmers' itch are related to the distribution of infected waterfowl and vary from year to year in any water body, but are generally most common in July when snail infections mature and parasite production increases.
Hot weather can contribute by speeding development of the parasites.
Infestations often disappear later in the summer when the snail host dies out. Extensive control measures using toxic chemicals are possible but usually not warranted. Individuals can control the effects of exposure by rubbing exposed surfaces of the body briskly with a towel after leaving the water. Bathers who remain in the water and follow this procedure upon leaving fair better than those who enter and leave the water frequently or are playing intermittently in shallow water. Taking a shower in water different from the lake water as soon as possible after leaving will also help.