Typically, hosts of avian schistosomes are migratory water birds, including shorebirds, ducks, and geese. Adult worms are found in the blood vessels and produce eggs that are swallowed and passed in the feces . On exposure to water, the eggs hatch and liberate a ciliated miracidium that infects a suitable molluscan intermediate host . The parasite develops in the intermediate host, usually a certain species of snail , to produce free-swimming cercariae that are released under appropriate conditions and penetrate the skin of the birds to complete the cycle . A number of species of dermatitis-producing cercariae have been described from both freshwater and saltwater environments, and exposure to either type of cercariae will sensitize persons to both.
Cercarial dermatitis occurs worldwide with cases reported from every continent except Antarctica.
In the US, cases are commonly reported from the Great Lakes region.