How Do Doctors Diagnose and Treat Schistosomiasis?

If the doctor suspects schistosomiasis, he or she examines a urine or stool (feces) sample taken from the patient to look for the worm's eggs. The doctor may need to examine several samples to identify the worms. He or she also may take a sample of blood for testing, although the blood test may not show evidence of the infestation unless it is done six to eight weeks after the patient's contact with the parasite. Occasionally, the doctor will order a tissue biopsy* to check for signs of the parasite in organs such as the liver.

Doctors may prescribe the drug praziquantel to treat the infestation. Patients usually need to take pills for only one to two days. For individuals who do not receive treatment and who continue to use the same tainted water source, the illness can last for years.

Can Schistosomiasis Cause Complications?

People who become repeatedly infested with schistosomiasis over many years can experience damage to the bladder, lungs, intestines, and liver. The disease is one of the leading causes of cirrhosis in the world. In some cases, the resulting scarring of the liver is so severe that blood flowing through the organ becomes partly blocked, causing a condition known as portal hypertension. Severe portal hypertension can make veins in the esophagus and stomach swell and bleed, sometimes to the point that the bleeding is fatal.

Other complications of the disease arise when the worm's eggs travel through the bloodstream to the spinal cord or brain, where they can cause seizures, inflammation of the spinal cord, or paralysis.

How Can Schistosomiasis Be Prevented?

Travelers visiting countries where schistosomiasis occurs should avoid wading, swimming, or bathing in any body of fresh water such as ponds, rivers, or lakes. Filtering or boiling drinking water for at least one minute kills parasites, including the Schistosoma worms. The Centers for Disease Control and Prevention recommends heating bathing water to 150 degrees Fahrenheit for at least five minutes to make sure it is frec of potential parasites.

To reduce the spread of schistosomiasis, health officials focus on educating people who live in areas where the worms are found. They teach the public how the parasites spread and encourage people not to urinate or have bowel movements in rivers and ponds. In addition, some countries have mounted extensive campaigns to reduce the worm population in their streams. A program in Japan, for instance, used several means to eliminate S. japonicun from the countr: d method was to encourage farmers to use horses instead of water buffalo when they were tending their rice paddies. The worms can enter these animals as they do humans, but horses are much less susceptible to the worms than water buffalo are.

A program in China includes several strategies. One of these involves the mass treatment of people and susceptible animals in certain regions with praziquantel. Another one involved the lowering of water levels in many streams and ponds to reduce the snails that are hosts during part of the worms' life cycle. Some carlier programs included the application of snail-destroying chemicals to streams, but scientists later discovered that many of those chemicals had unintended consequences, such as killing fish. China's schistosomiasis-reduction program was quite successful, but suffered a setback after extreme flooding along the Yangtze River in 1998 brought water levels up again. This rise in the water allowed the snails to repopulate and resulted in an outbreak in 2004 when about 850,000 people were infected. Control efforts in China continued as of 2008.

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