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Schistosomiasis (Bilharzia) and Swimmer's Itch
Schistosomiasis or bilharzia is a disease affecting many people in developing countries.It is also called snail fever. A similar worm causes swimmer's itch in North America but is a distinctly different condition. Both diseasesare caused by flatworms that infect snails and some other type of vertebrate. In both cases snails that are infected with the worms pass the worms on to people through shallow wading water contact The parasites that cause severe disease in humans specifcally adapted to humans cause greater disease. The Swimmer's itch types infect other animals like birds and accidentally infect people and are not very succesful being able to only partially penetrate the skin, They die in the skin but not before setting up a local irritative reaction hense “swimmmer's itch”.
Schistosomiasis worms invade and then inhabit the body. A mating male and female pair couple will set up and live in the body usually 4-5 years but this honeymoon can last 20 years. The worms themselves are not the problem but the 300-3000 eggs per day they lay are. These eggs set up intense irritation and cause problems in different organs. This can include problems in the liver, bladder but also the brain and spinal chord! Chronic infestation causes bladder cancer! Chronic infections usually happens to people living longterm with frequent reexposure but travellers dipping in the wrong waters also get sick.
The swimmer's itch parasite is naturally found in many Manitoba lakes and is more of a nuisance and not lifethreatening and does not lead to chronic health problems. The Manitoban swimmer's itch worm infects waterfowl and aquatic mammals, (muskrat and beaver). Eggs are laid in the host by adult worms and are passed into the water through the host's feces. While in the water, these eggs hatch into microscopic worms. To complete their life cycle, they must enter the tissues of a snail where they mature. Signs of swimmer's itch are noticeable soon after you get out of the water. Once dry, you will detect tingling sensations on exposed parts of your body. The next sign is the development of small red spots where the organism has penetrated through your skin. Hours later, the tingling sensation will cease and the red spots will enlarge and become itchy. The degree of discomfort varies with the individual, the severity of the infestation, and prior exposure. If these symptoms develop, anti-itch medications, such as lotions and some antihistamines, will help relieve them. Your family physician or pharmacist can recommend the best treatment.
Many of the recommendations that Manitobans can use to prevent Swimmer's Itch also will be useful for travelers to know to prevent Schistosomiasis. Swimmer's itch shows up in about 3-17 Manitoba lakes every summer. Avoid swimming in areas known to have swimmer's itch. Check for warning signs posted on beaches. Swimmer's itch usually starts showing up in Manitoba lakes in June-warm water accelerates its development. Wind can concentrate these parasites in shallow beach areas Towel down briskly right after leaving the water to help remove the parasite. Take a shower immediately after leaving the suspected area. Avoid areas with large numbers of aquatic plants. These are ideal habitats for snails and swimmer's itch parasites. If you get swimmer's itch from a Manitoba lake or to see if swimmers itch has been reported at your favourite lake contact the Water Quality Management Section of Manitoba Water Stewardship 945-7100 or 1-800-282-8069 (7100).http://www.gov.mb.ca/conservation/index.html?pages/publs97/cwgtext/swimitch.html
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