Air drying gives the parasite time to burrow into the skin. This can happen when someone air dries after being in water where the parasite is living. The parasites are unable to live in a human and soon die. An interesting note is that previous contact with cercariae can lead to a more immediate and intense immune response.People get swimmer’s itch when the parasites burrow into their skin. Scratching the affected areas may result in secondary bacterial infections. After a period of approximately 12 hours, pruritic papules may become vesicular. This is an indication of initial penetration of the cercariae. Symptoms include reddening and itching of exposed skin in the water or immediately after emerging. and Ornithobilharzia spp.Ĭercarial dermatitis (swimmer’s itch) is a cutaneous inflammatory response usually associated with penetration of the skin by cercariae of bird schistosomes. Marine (saltwater or brackish) species include Austrobilharzia spp. Freshwater species include Trichobilharzia spp., Gigantobilharzia huronensis, Bilharziella polonica, Heterobilharzia americana, Schistosomatium spp., and Bivitellobiharzia spp. In the United States, cases are commonly reported from the Great Lakes region.Īgents of cercarial dermatitis exist in both marine and freshwater environments. Many species are widespread due to the migration of suitable bird hosts and introduction of snail intermediate hosts. Geographic DistributionĬercarial dermatitis occurs worldwide with cases reported from every inhabited continent. Snail intermediate hosts are diverse and will depend on the parasite species and the habitat of the definitive host. Among the more well-described dermatitis-causing mammalian schistosomes, Heterobilharzia americana is found in dogs and raccoons, and Schistosoma spindale normally infects ruminant livestock. have been identified in goldfinches, starlings, pelicans, cardinals, crows, canaries, and more. with many species of anseriforms, wading birds, and seabirds. are often associated with anseriform birds (e.g. Though some schistosomes of mammals cause cercarial dermatitis, the vast majority involved are of avian origin, and many of which exhibit relatively low specificity among bird hosts. A number of species of trematodes with dermatitis-producing cercariae have been described from both freshwater and saltwater environments, and exposure to either type of cercaria will sensitize persons to both. Humans are inadvertent and inappropriate hosts cercariae may penetrate the skin but do not develop further. The parasite develops in the intermediate host to produce free-swimming cercariae that are released under appropriate conditions and penetrate the skin of the birds and migrate to the blood vessels to complete the cycle. Life CycleĪdult worms are found in the blood vessels of definitive hosts and produce eggs that are passed in the feces On exposure to water, the eggs hatch and liberate a ciliated miracidium that infects a suitable snail (gastropod) intermediate host. Cercarial dermatitis occurs on the exposed skin outside of close-fitting garments. The areas of skin affected by seabather’s eruption is generally under the garments worn by bathers and swimmers where the organisms are trapped after the person leaves the water. These schistosomes all use different snail intermediate hosts, commonly those from the families Nassariidae, Lymnaeidae, and Physidae.Ĭercarial dermatitis should not be confused with seabather’s eruption, which is caused by the larval stage of cnidarians (e.g., jellyfish). ( =Orientobilharzia) turkestanicum) occur occasionally. Cases involving mammalian schistosomes Heterobilharzia americana, Bivitellobiharzia spp., Schistosomatium spp., and some aberrant zoonotic Schistosoma spp. ), Bilharziella polonica, and Gigantobilharzia huronensis. Other avian schistosomes that cause cercarial dermatitis include Ornithobilharzia spp., Austrobilharzia spp. Several genera/species are known to cause cercarial dermatitis the most commonly implicated genus globally is the waterfowl schistosome Trichobilharzia spp. Skin penetration by these zoonotic cercariae causes dermatitis, but the cercariae do not mature into adults in the human body. These cercariae seem to have a chemotrophic reaction to secretions from the skin and are not as host-specific as other types of human-infecting schistosomes. Cercarial dermatitis (“swimmer’s itch”, “clam-digger’s itch”, “duck itch”) is caused by the cercariae of certain species of schistosomes whose normal hosts are birds and mammals other than humans.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |