The miracidium uses cilia to follow chemical and physical cues thought to increase its chances of finding the first intermediate host in its life cycle, a freshwater snail. Once a schistosome egg is immersed in water, a short-lived, non-feeding, free-living stage known as the miracidium emerges.These parasites use both freshwater snails and vertebrates as hosts in their parasitic life cycles as follows: In marine habitats, especially along the coasts, swimmer's itch can occur as well. Other taxa reported to cause the reaction include Bilharziella polonica and Schistosoma bovis. It can also be caused by schistosome parasites of non-avian vertebrates, such as Schistosomatium douthitti, which infects snails and rodents. The genera most commonly associated with swimmer's itch in humans are Trichobilharzia and Gigantobilharzia.
The condition was known to exist as early as the 1800s, but it was not until 1928 that a biologist found that the dermatitis was caused by the larval stage of a group of flatworm parasites in the family Schistosomatidae. Swimmer's itch has probably been around as long as humans. In addition, bathing in oatmeal, baking soda, or Epsom salts can also provide relief of symptoms. Orally administered hydroxyzine, an antihistamine, is sometimes prescribed to treat swimmer's itch and similar dermal allergic reactions. There are no permanent effects to people from this condition. People repeatedly exposed to cercariae develop heavier symptoms with faster onset. The intense itching, which peaks after 48–72 hours, is associated with pain and swelling of the affected areas. The papules disappear in 1–2 weeks but secondary effects from scratching can continue longer. Within 10–12 hours these turn into very itchy papules that reach their worst by the second or third day. Initially, wheals develop quickly, then turn into maculae in about half an hour. The main symptom is itchy papules (raised skin) that commonly occur within 2 days of infection. Nevertheless, the condition has been regarded as an emerging infectious disease. Incidence may be on the rise, although this may also be attributed to better monitoring. It is common in freshwater, brackish and marine habitats worldwide.
Whats swimmers itch skin#
Swimmer's itch, cercarial dermatitis or schistosome dermatitis is a short-term allergic immune reaction occurring in the skin of humans that have been infected by water-borne schistosomes, a type of flatworms. Cercarial dermatitis on lower legs, four days after spending a day in the shallows of a lake
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