Schistosomiasis (Bilharzia):
Risk, Prevention and Vaccination

Schistosomiasis, formerly also known as bilharzia, is a parasitic worm infection found in parts of Africa, Latin America, the Middle East, China, the Philippines and Southeast Asia. There is currently no vaccine available against schistosomiasis. The only way to prevent the disease is to avoid contaminated freshwater. Therefore, do not swim or paddle in freshwater.

What is schistosomiasis?

Schistosomiasis is an infection caused by worms that live in freshwater. The larvae of these worms are extremely small and develop in freshwater snails. They are then released into the water in large numbers, where they can come into contact with humans. The larvae attach to the skin and can penetrate it. This may sometimes cause itching or a skin rash. Through the bloodstream, the larvae travel to other parts of the body, usually the intestinal wall or bladder wall. There, the larvae settle and lay eggs.

A few weeks after infection, when the larvae begin to settle in the body, you may experience fever, muscle pain, skin rash, shortness of breath and an irritating cough. When the larvae start laying eggs, they can trigger an inflammatory reaction in the intestinal wall or bladder wall. This may cause symptoms such as abdominal pain, blood in the urine or diarrhoea (sometimes with blood).

Most people do not develop symptoms from schistosomiasis. People who do develop symptoms, it can sometimes take months or even years before they appear.

In which countries does schistosomiasis occur?

Schistosomiasis occurs in tropical and subtropical countries. You can become infected in various parts of Africa, Latin America, the Middle East, China, the Philippines and Southeast Asia. Travellers to countries such as Nigeria, Sudan, Kenya, Malawi, the Democratic Republic of the Congo, Egypt, Brazil, Suriname, Venezuela, Cambodia and Laos have an increased risk.

High-risk areas

In some areas, the risk of schistosomiasis is particularly high:

• Sub-Saharan Africa, especially Lake Malawi
• Egypt, the Nile Valley
• Brazil
• Southeast Asia, especially the Mekong River basin

Would you like to know the risks for your travel destination? Then visit our country page.

What are the symptoms of schistosomiasis?

The symptoms of schistosomiasis vary depending on the stage of the infection. Shortly after swimming in contaminated water, you may experience itching and a skin rash. Two to six weeks after infection, the following symptoms may occur:

• Fever
• Muscle pain
• Shortness of breath
• Irritating cough

In the later stage of the infection, when the worms begin laying eggs, you may experience:

• Abdominal complaints
• Blood in the urine
• Diarrhoea
• Liver problems

Is there a vaccine against schistosomiasis?

Currently there is no vaccine available against schistosomiasis. Infection also cannot be prevented by taking medication before or after exposure. If you are offered medication locally, for example by diving schools, you should therefore not take it without proper medical advice. The only way to prevent the disease is to avoid contact with contaminated freshwater.

Are you concerned that you may have been infected? At least six weeks after your last contact with freshwater, you can ask for a blood test for schistosomiasis.

How can you prevent schistosomiasis while travelling?

The only way to prevent schistosomiasis is to avoid contact with contaminated freshwater. Therefore, do not swim or paddle in freshwater. If you do come into contact with freshwater, dry yourself quickly and thoroughly. Do not allow the water to dry on your skin.

In areas where schistosomiasis occurs, check where the shower water comes from. Sometimes it is taken directly from lakes or rivers. In that case, it is advisable to avoid the shower water as well. Also make sure you only drink safe water.

Swimming in the sea or in chlorinated swimming pools is safe.