However, after repeated exposure, sensitivity may develop. In summer, the water temperature reaches the appropriate level for snails to reproduce and grow rapidly, migrating aquatic birds infected with the trematode parasite return from their winter habitats or domesticated aquatic birds return to full activity, and people go out swimming.Ī swimmer’s first exposure to infested water may not result in any reaction. Several combining factors may lead to infection. Certain aquatic mammals such as muskrats and beavers can also be a host. Waterfowl are the usual hosts of these flatworms, with humans only infected accidentally. However, an infected snail will continue to produce cercariae for it's entire life, which can be up to two months. Larvae are generally infective for 24 hours only, once they are released from the snail. After the parasite enters the skin, it dies and may cause Dermatitis in individuals who have been previously infected. If someone is unfortunate enough to be in the wrong place at the wrong time, the cercariae can penetrate the outer layer of human skin. Again, this is through either skin penetration or ingestion. These cercaria burrow out of the snail, seeking a bird host to repeat the cycle. In about a month, the sporocysts develop into cercaria. ![]() Within the snail, the miracidium form the sporocyst. Once the miracidium find the right snail, they infest them through skin or the mouth. These miracidium swim through the water seeking a specific species of aquatic snail, Lynmnaeidae or Physidae. When the host defecates into the water, the eggs hatch, which is called miracidium. ![]() There, the parasites develop to adulthood, when female worms lay eggs that end up in the host's intestines. Swimmer's Itch occurs when a film of cercariae-infested water dries on exposed skin.Ĭercariae penetrate the skin of a bird or mammal, migrate through the various organs, and reside in the blood vessels, usually those surrounding the intestine. Swimmer's Itch develops on exposed areas of skin after contact with these larva when they penetrate the person's skin. Immature larva, called cercariae, of parasitic flatworms, called schistosomes, are released from infected snails into fresh and/or salt water. Swimmer's Itch, sometimes referred to as cercarial dermatitis, is a skin rash caused by an allergic reaction to infestations of certain parasites of birds and mammals. People who have been previously exposed to swimmer's Itch are more susceptible. Symptoms begin as red marks from larvae penetration and itching, which becomes more intense a few hours later, occasionally developing into papules, hives, or blisters. These cercaria penetrate the human host through exposed skin or the mouth instead of the intended waterfowl or aquatic mammal. Condition, sometimes called cercarial dermatitis, is a skin rash caused by infestation by the larvae of a flatworm that typically affects snails and waterfowl.
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