The genera most commonly associated with swimmer’s itch in humans are Trichobilharzia and Gigantobilharzia. Trematodes in these groups normally complete their life cycles in birds. However, swimmer’s itch can also be caused by schistosome parasites of non-avian vertebrates, such as Schistosomatium douthitti, which infects snails and rodents. Other taxa reported to cause the reaction include Bilharziella polonica and Schistosoma bovis.