Schistosomiasis

What is schistosomiasis?

Schistosomiasis is a disease caused by a parasite worm that lives in certain types of freshwater snails. The parasite leaves the snail and enters the water where is can enter a person’s body through the skin when a person wades or swims in contaminated freshwater.  

Within days of becoming infected, a person may develop a rash or itchy skin. Fever, chills, cough, and muscle aches may begin within one to two months of infection. Most people have no symptoms early on, but left untreated, schistosomiasis can cause more serious health problems.

Children who are repeatedly infected can develop anemia, malnutrition, and learning difficulties. After years of infection, the parasite can also damage the liver, intestine, spleen, lungs, and bladder.

Who is at risk?

Travelers going to countries in Africa, South America, the Middle East, China, and Southeast Asia can get schistosomiasis.  The freshwater snails that carry schistosomiasis are found in streams, rivers, and lakes in many countries around the world. Anyone who swims, bathes, or wades in freshwater streams, rivers, ponds, lakes, or untreated pools where snails that carry schistosomiasis live can get infected.

Many travelers who get schistosomiasis traveled to sub-Saharan Africa to popular tourist destinations. These include rivers and water sources such as Lake Malawi, Lake Tanganyika, Lake Victoria, the Omo River, the Zambezi River, and the Nile River.

Adventure travelers, Peace Corps volunteers, missionaries, soldiers, and ecotourists may be more likely to get schistosomiasis because of their work and activities. Local claims that there is no schistosomiasis in a body of freshwater are not reliable and precautions should be taken to prevent exposure.

What can travelers do to prevent schistosomiasis?

If you are visiting or live in an area where schistosomiasis is a concern:

  • Avoid swimming, bathing, or wading in freshwater sources, such as lakes, rivers, ponds, and wetlands. Swimming in the ocean and in chlorinated swimming pools is safe.
  • Drink safe water.
    • Although schistosomiasis is not transmitted by swallowing contaminated water, if contaminated water touches your mouth or lips, you could become infected.
    • Because water coming directly from canals, lakes, rivers, streams, or springs may be contaminated with other infectious organisms, bring your water to a rolling boil for one minute or filter water before drinking it. A rolling boil for at least one minute will kill any harmful parasites, bacteria, or viruses present.
    • Iodine treatment alone WILL NOT GUARANTEE that water is safe and free of all parasites.
  • Boil water used for bathing. Bring the water to a rolling boil for 1 minute, then let it cool before bathing to avoid scalding. Water held in a storage tank for at least one to two days should be safe for bathing.
  • Quickly dry off completely with a towel after an accidental, brief water exposure. This may help prevent parasites from penetrating the skin. However, do not rely on towel drying alone to prevent schistosomiasis.

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If you traveled and feel sick, particularly if you have a fever, talk to a healthcare provider and tell them about your travel. Avoid contact with other people while you are sick.

If you need medical care abroad, see Getting Health Care Abroad.

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