Schistosomiasis (Bilharzia): Symptoms, Prevention and UK Travel Advice

Schistosomiasis, frequently referred to as bilharzia, is an infection caused by parasitic flatworms known as schistosomes. While virtually unheard of in the United Kingdom's natural waters, it is a significant health concern for British travellers visiting tropical and subtropical regions. According to the NHS and the World Health Organization, it is the second most socio-economically devastating parasitic disease globally, after malaria.

The infection begins when larval forms of the parasite, released by freshwater snails, penetrate human skin during contact with infested water. Once inside the body, the larvae develop into adult worms that live in the blood vessels, where the females release eggs. It is the body's immune reaction to these eggs, rather than the worms themselves, that causes the multi-system symptoms associated with the disease.

The symptoms of schistosomiasis can vary depending on the stage of the infection. Many travellers do not experience any symptoms immediately after exposure, which can lead to delayed diagnosis.

Early Stage (Acute Schistosomiasis)

Within hours or days of exposure, some individuals develop 'swimmer's itch'—a tingly, itchy red rash where the larvae entered the skin. A few weeks later, some may develop 'Katayama fever,' which includes:

• High temperature (fever) and chills
• A dry cough
• Muscle aches and joint pain
• General malaise and fatigue
• Abdominal pain or diarrhoea

Chronic Stage

If the infection is not treated, the parasites can remain in the body for years. Chronic schistosomiasis can lead to serious long-term health issues, including inflammation of the liver, bladder damage, and even an increased risk of bladder cancer. Symptoms in this stage depend on where the eggs have settled, often manifesting as blood in the urine or stool.

When planning a trip abroad, it is essential to check the NICE (National Institute for Health and Care Excellence) and FitForTravel guidelines for your specific destination. Schistosomiasis is most prevalent in:

• Africa: Particularly Lake Malawi, the Nile River, and Great Lakes regions.
• South America: Parts of Brazil, Suriname, and Venezuela.
• Southeast Asia: The Mekong River basin and parts of Indonesia and the Philippines.
• Middle East: Countries such as Yemen and Saudi Arabia.

Even if the water looks clear and the locals are swimming, travellers should remain cautious, as the parasite is invisible to the naked eye.

The only guaranteed way to prevent schistosomiasis is to avoid contact with freshwater in endemic areas. Follow these evidence-based safety tips:

• Avoid Freshwater Swimming: Stick to chlorinated swimming pools or the ocean (saltwater is safe).
• Boil Water: If you must use freshwater for drinking or brushing teeth, boil it for at least one minute. Filtered water is not always safe from larvae.
• Heat Bath Water: If your accommodation uses unfiltered lake water for showers, heat it to 50°C for five minutes or let it stand for 48 hours before use.
• Vigorous Towel Drying: If you accidentally fall into freshwater, dry yourself immediately and vigorously with a towel to help prevent larvae from penetrating the skin.
• Waterproof Footwear: Wear boots if you must wade through marshy areas or streams.

If you suspect you have been exposed to bilharzia, you should seek medical advice upon your return to the UK. Diagnosis usually involves blood tests to look for antibodies or stool/urine samples to identify parasite eggs. However, it can take up to 12 weeks after exposure for these tests to become accurate.

The standard treatment is a short course of a medication called Praziquantel. This drug is highly effective at killing the adult worms. Treatment is generally straightforward and prevents the progression to chronic disease, which is why early consultation with a healthcare provider is vital.

Navigating travel health risks can be complex. If you are planning a trip to a high-risk area or have recently returned and feel unwell, you can speak to a GP online for a professional assessment. An online doctor can review your travel itinerary, discuss your symptoms, and provide guidance on the necessary tests or referrals within the UK healthcare system.

Using an online service allows you to access expert advice from the comfort of your home, ensuring that you are fully prepared before you fly or receive the right follow-up care when you land. Our clinical team follows current UK health protocols to ensure you receive evidence-based care tailored to your travel history.