Schistosomiasis (bilharzia): symptoms, risk areas and treatment

The NHS says schistosomiasis often has no symptoms, or only produces them weeks, months or years after infection. TravelHealthPro adds that in travellers it commonly occurs without symptoms. When symptoms do appear they can include the following.

• An itchy, bumpy rash or prickly, stinging feeling on skin that was in the water, known as swimmer's itch, usually within a few days of exposure.

• A high temperature (fever), headaches, tummy ache, muscle aches and joint pain.

• Feeling tired and having a cough.

• Diarrhoea, which may have blood in it.

• Blood in the pee.

• Blisters, sores or bleeding from the vagina, or pain during sex.

According to the NHS, schistosomiasis is treated with tablets that kill the worms. You may also be given steroid medicine to reduce the side effects of your body fighting the infection. You normally need only one course, but you may be given more medicine if symptoms do not improve.

The NHS says a doctor may refer you to a specialist if they think you may have the infection, so treatment is often supervised by a hospital service that deals with infections acquired abroad.

Schistosomiasis is a parasitic infection caused by Schistosoma worms. TravelHealthPro, the UK travel health service, explains that infection occurs through direct contact with contaminated fresh water where certain snails may carry the parasite. Larval forms of the worm are released from the snails into the water and can penetrate human skin and move to internal organs.

You cannot see the worms in the water. The NHS notes that they may be present even when water looks clean. If water containing the worms gets on your skin, for example while swimming, washing or walking in water, they can burrow into the skin and get into the body.

The NHS says the worms are found in tropical and sub-tropical parts of the world, including most of Africa, the Middle East, southern and south-east Asia, and some parts of South America and the Caribbean.

TravelHealthPro says that in travellers it is most often acquired in Africa, and lists common travel destinations where it occurs as Malawi, particularly Lake Malawi, Egypt, Kenya, Tanzania, South Africa and some areas of Brazil. Travellers are at risk if they wade, swim or have other contact with fresh water from lakes or rivers in areas where it is common. Country-specific information is available from TravelHealthPro, and the NHS advises checking before you travel.

The NHS advises seeing a GP if you have travelled to an area with schistosomiasis and fresh water from a lake, river or pond got on your skin or in your mouth, and you have a rash or feel unwell. Tell anyone you speak to about your travel. TravelHealthPro goes further: people who have been swimming or bathing in fresh water in areas where the disease is common should be advised to undergo screening, ideally by an infectious diseases specialist, even if they feel well.

This matters because the infection may be silent while quietly causing damage. The NHS says other symptoms usually begin 2 to 12 weeks after infection, but they can start at any time.

The NHS says a doctor will ask about your symptoms and where you have travelled. If they think you may have the infection, they may refer you to a specialist. You may need to give samples of your pee and poo and have a blood test. The exact tests chosen can depend on how long ago you were exposed, which is why a clear account of the dates and places of travel is useful.

The NHS and TravelHealthPro describe infection as coming from contact with contaminated fresh water, where worms released from certain snails burrow into the skin or can enter through the lips or mouth. Neither page describes it as spreading directly from person to person.

It is not found in the UK, so the question is relevant for people who have travelled or lived in an affected area. If you have been exposed, the practical risk is to your own health: the NHS says it can cause serious long-term problems if not treated, and TravelHealthPro mentions intestinal or bladder disease. Tell anyone who treats you about your travel history.

The NHS lists these practical measures if you are travelling where there is a risk.

Schistosomiasis is usually not an emergency, but see a GP promptly if you have been in fresh water in a risk area and have a rash or feel unwell. The NHS lists a high temperature, tummy ache, blood in diarrhoea or in the pee and a cough among the symptoms.

If you develop severe symptoms, such as a very high fever, severe tummy pain, heavy bleeding or difficulty breathing, call NHS 111 or go to A&E and say that you have been in fresh water in a tropical area. The NHS pages do not set out a separate emergency threshold for schistosomiasis, so use ordinary urgent-care rules.

GPs can arrange initial tests and refer to NHS infectious diseases or tropical medicine departments, and NHS treatment is free. Private travel clinics offer pre-travel advice and some offer post-travel screening, which can be convenient if you have returned from a high-risk area and feel well.

Whichever route you use, give a full travel history, mention fresh water exposure specifically, and make sure results and any treatment are shared with your GP.