Tanzania
Schistosomiasis

Tanzania: General Health Risks

Schistosomiasis

Infection is transmitted by snails living in fresh water such as lakes, rivers, streams and ponds in Africa, and some countries in Southeast Asia, South America, and the Caribbean.

Description

Schistosomiasis, also known as Bilharzia, is caused by Schistosoma trematode flatworms. It is transmitted by snails living in fresh water such as lakes, rivers, streams and ponds. This preventable disease affects approximately 243 million people worldwide. The following flatworms – S. haematobium, S. mansoni, S. guineensis,  S. intercalatum, S. mekongi, S. japonicum as well as S. mattheei and S. malayensis are responsible for Schistosomiasis in humans causing damage either to the urinary tract, bladder, kidneys, liver, or gastro-intestinal system. Schistosomiasis is a Neglected Tropical Disease (NTD)*. Many countries affected by the disease have active health education and eradication programs focusing on improved sanitation and snail control.

* Neglected Tropical Diseases are chronic infections that are typically endemic in low income countries. They prevent affected adults and children from going to school, working, or fully participating in community life, contributing to stigma and the cycle of poverty.

Risk 

Travellers swimming in fresh water in Africa, Southeast Asia, South America, and some Caribbean islands are at greater risk.

Symptoms

Initial symptoms usually appear within days or weeks after being infected and include a skin rash, fever, headache, muscle ache, bloody diarrhea, cough, malaise, and abdominal pain. If untreated, Schistosomiasis can become a chronic illness as the flatworm eggs damage the lining of abdominal organs, female genital organs, the heart, lungs, and rarely the brain. Chronic Schistosomiasis can cause irreversible damage, including cancer. Treatment includes taking the anthelminthic drug Praziquantel.

Prevention

The primary way to prevent Schistosomiasis is to avoid swimming in fresh water and eating raw foods which have not been washed with purified water. Additional prevention advice includes: 

• In countries where Schistosomiasis is endemic, avoid contact with fresh water. There will be situations where you will be tempted to disregard this simple advice. There is no risk in seawater.
• If you are planning a trip into the jungle or desert, make sure it is a short one, so that you can withstand the heat and are not tempted to cool off in a pond or stream. Make sure you do not run out of purified water.
• If you must pass through streams or swamps, wear high waterproof boots or hip waders.
• Stay away from the banks of streams and rivers; snails abound in shallow water where they feed on organic waste and aquatic vegetation. Snail presence is minimal in the deeper ends of lakes, rivers, and streams where water tends to flow faster.
• Avoid contact with fresh water during peak daylight hours when the cercariae emerge from the snails and are most active.
• If you accidentally come into contact with fresh water, rub your skin immediately with rubbing alcohol and a dry towel to reduce the possibility of infection.
• If you are travelling overland by car, carry a pair of rubber gloves in case you have to dip your hands into a stream or pond to get water for the radiator.
• Water from a river or lake used for bathing and washing should be boiled or chlorinated.
• Water for washing and bathing is relatively safe if it has been stored for 2-3 days (the period generally accepted as the life span of cercariae), provided that the container is free of snails.
• Drinking water should be boiled or treated with chlorine tables, as the cercariae may burrow through the mucosa of the mouth.
• Make sure vegetables are well cooked and avoid salads since the leaves may have been washed with infected water.