Schistosomiasis (bilharzia)

Schistosomiasis or bilharzia is a disease produced by the larvae of a flatworm. The worm larvae infect certain varieties of freshwater snails found in East Africa rivers, streams, lakes and particularly behind dams. The worms multiply and are eventually discharged into the water surrounding the snails. The infection develops after the larvae of a flatworm have penetrated the skin. These larvae can penetrate unbroken skin, the lining of the mouth or the gastrointestinal tract. The worm attaches to the intestine or bladder, and begins producing eggs. Worm eggs can be shed for many years under conditions of poor sanitation and hygiene, and waterways become contaminated through human waste.

Areas of disease

Schistosomiasis infection is widespread in many countries of Sub-Saharan Africa, including Burundi, Eritrea, Ethiopia, Kenya, Madagascar, Malawi, Mauritius, Mozambique, Rwanda, Somalia, Tanzania, Uganda, and Zanzibar. Little information is available for Comoros Island, Djibouti, Mayotte, Reunion, and Seychelles. The risk is a function of the frequency and degree of contact with contaminated fresh water for bathing, wading, or swimming.

Symptoms and disease course

A general feeling of being unwell may be the first symptom of disease, and some may complain of a tingling sensation and a light rash -- swimmer's itch -- around the area where the flatworm entered. Anywhere from two to 10 weeks later, a nonspecific illness with fever, aching, cough, diarrhea or gland enlargement may develop. Later on, passage of blood in the urine (redwater fever) is characteristic of infections acquired in central and eastem Africa, but a range of intestinal, liver, kidney, lung or central nervous system problems can ensue. Many serious cases are the result of the worm ending up in an unusual location such as the brain or spinal cord. The established disease is quite unpleasant.

Prevention

The traveler cannot distinguish between infested and non-infested water. Therefore, swimming in fresh water in rural areas where schistosomiasis is present should be avoided. Even deep water can be infected. Bath water should either be heated to 50 degrees C (122 degrees F) for five minutes or treated with chlorine or iodine as is done for drinking water. If exposed, immediate and vigorous towel drying and application of rubbing alcohol to the exposed areas may reduce the risk of infection. There is no risk in salt water.

Testing

Proof of infection is obtained when schistosome eggs are seen microscopically in the urine or feces. In the early symptomless phase where such tests may be negative, a blood count may show an 'eosinophilia', suggesting exposure to a parasite. A test of blood antibodies is the best way to confirm exposure, but it may remain negative in the early stages of the disease.

Treatment

Seek medical attention if you have been exposed to the disease and tell the doctor your suspicions, as schistosomiasis in the early stages can be confused with malaria or typhoid. Screening procedures are available for those who suspect infection, and schistosomiasis is treatable with drugs. Treatment is fairly simple, with a course of praziquantel (Biltricide) tablets. Remember, however, that tests may be negative in the early phase of the disease and repeat testing may be necessary.

Diseases