Schistosomiasis

Schistosomiasis also known as bilharzia. It is a disease caused by parasitic worms. Infection with Schistosoma mansoni, S. haematobium, and S. japonicum causes illness in humans. Infection occurs when your skin comes in contact with contaminated fresh water in which certain types of snails that carry schistosomes are living.

Schistosoma eggs contaminate fresh water when infected people urinate or defecate in the water. The eggs hatch and if certain types of snails are present in the water, the parasites grow and develop inside the snails. The parasite leaves the snail and enters the water where it can survive for about 48 hours. Schistosoma parasites can penetrate the skin of persons who are wading, swimming, bathing, or washing in contaminated water. Within several weeks, worms grow inside the blood vessels of the body and produce eggs. Some of these eggs travel to the bladder or intestines and are passed into the urine or stool.

If you live in or travel to areas where schistosomiasis occurs and your skin comes in contact with fresh water from canals, rivers, streams, or lakes, you are at risk of getting schistosomiasis.

SYMPTOMS

  • Within days after becoming infected, you may develop a rash or itchy skin.

  • Fever, chills, cough, and muscle aches can begin within 1-2 months of infection. Most people do not have any symptoms at this early phase of infection.

  • Eggs travel to the liver or pass into the intestine or bladder.

  • Rarely, eggs are found in the brain or spinal cord and can cause seizures, paralysis, or spinal cord inflammation.

  • For people who are repeatedly infected for many years, the parasite can damage the:

  • Liver.

  • Intestines.

  • Lungs.

  • Bladder.

  • Symptoms are caused by the body's reaction to the eggs produced by worms, not by the worms themselves.

DIAGNOSIS

  • See your caregiver. If you have traveled to countries where this disease is found and had contact with fresh water, describe in detail where you traveled and how long you were there. Explain that you may have been exposed to contaminated water.

  • Your health care provider may ask you to provide stool or urine samples. They will check this sample to see if you have the parasite. A blood test has been developed and is available at CDC. For accurate results, you must wait 6 to 8 weeks after your last exposure to contaminated water before the blood sample is taken.

TREATMENT

Safe and effective drugs are available for the treatment of schistosomiasis and are taken for one to two days.

PREVENTION

  • Avoid swimming or wading in fresh water when you are in countries in which schistosomiasis occurs. Swimming in the ocean and in chlorinated swimming pools is generally thought to be safe.

  • Drink safe water. Because there is no way to make sure that water coming directly from canals, lakes, rivers, streams or springs is safe, you should either boil water for 1 minute or filter water before drinking it. Boiling water for at least 1 minute will usually kill harmful parasites, bacteria, or viruses present. Iodine treatment alone WILL NOT GUARANTEE that water is safe and free of all parasites.

  • Bath water should be heated for 5 minutes at 150° F. Water held in a storage tank for at least 48 hours should be safe for showering.

  • Vigorous towel drying after an accidental, very brief water exposure may help to prevent the Schistosoma parasite from penetrating the skin. You should NOT rely on vigorous towel drying to prevent schistosomiasis.

Information courtesy of the CDC.