Travel health
Schistosomiasis (Bilharzia)
There is no vaccine for schistosomiasis (bilharzia): you avoid it by keeping your skin out of untreated fresh water where the parasite lives, and you get a blood test on your return if that didn't quite go to plan. Our Timperley pharmacists cover both ends of the trip.
What is Schistosomiasis?
Schistosomiasis is an infection with tiny parasitic flatworms called schistosomes. Their larvae develop inside certain freshwater snails and are released into the surrounding water, where they can burrow through intact skin in the time it takes to wade out to a boat or rinse mud off your feet. There is usually nothing to feel. The larvae travel to the liver, mature, pair up and settle in the small veins around the bowel or bladder, where they lay eggs, and it is that long, quiet egg-laying phase that scars the bladder, bowel and liver if nobody treats it. It helps to be clear about what does not carry the parasite. Sea water is safe, and so are a properly chlorinated pool, rain, and water you have boiled, filtered or bought bottled. The danger is untreated fresh water where the snails live: lakes, rivers, ponds, dams and irrigation channels. Still or slow-moving water near reeds and banks is the highest risk, because that is where the snails gather, and the longer your skin is in contact the greater the chance of infection. A quick splash through a fast-flowing stream is lower risk, but not zero. Early infection is usually silent. Some people notice an itchy rash within a few days of being in the water; a smaller number develop a feverish illness weeks later; many feel fine and only find out because they were tested. Once diagnosed it is treatable with tablets, arranged through a specialist service, so for anyone coming home to Manchester after freshwater contact the aim is simple: know you were exposed, and get the blood test at the right time.
Where is there a risk of Schistosomiasis?
Sub-Saharan Africa, above all the lakes and rivers travellers love: Lake Malawi from Cape Maclear to Nkhata Bay, the Ugandan, Kenyan and Tanzanian shores of Lake Victoria, and the Nile, including the rafting stretch below Jinja. The Zambezi, including Lake Kariba on the Zambia and Zimbabwe border and the Lower Zambezi canoe channels, and Lake Tanganyika, shared by Tanzania, Zambia, Burundi and the Democratic Republic of the Congo. Rivers, dams and irrigation schemes across the rest of Africa, such as Ethiopia's Omo River, the Okavango channels in Botswana and northern Namibia's rivers; new dams and irrigated farmland create snail habitat, so the risk map shifts. Parts of the Middle East, and the island of Corsica, where the bladder form (Schistosoma haematobium) has been found. Brazil, Venezuela and Suriname, some Caribbean islands, and in Asia the lakes and river basins of China, the Philippines, parts of Indonesia and the Mekong in Laos and Cambodia, where flooded paddy fields and irrigation channels suit the snails.
Who is at risk of Schistosomiasis?
Anyone whose skin touches untreated fresh water in these areas can be infected, however briefly and however clean the water looks, but some travellers run a far higher risk. River rafting and canoe trips, wild swimming and lakeside backpacking are the classic ones, and TravelHealthPro links the growth in adventure and off-the-beaten-track travel to rising cases in people returning to the UK. Outbreaks have followed school trips and group river journeys in Africa. Longer stays mean repeated exposure: gap-year volunteers, aid workers, expatriates and people visiting family in rural areas who bathe or wash in the river because everyone does. Children paddle and splash without a second thought, and safari guests are not exempt either; a dip in a lodge's lake is enough. Two things catch people out. Local assurances that a stretch of water is 'bilharzia-free' are not reliable, and feeling well afterwards proves nothing, because early infection is usually symptomless. If you are travelling from Trafford or Cheshire to any of these regions, tell us about planned water activities at your consultation and we will build them into your plan.
What are the symptoms of Schistosomiasis?
An itchy, prickly rash where the water touched you ('swimmer's itch'), usually within a few days
Often nothing at all: most infected travellers have no early symptoms, which is why testing matters
Fever, chills, tiredness and aching muscles 2 to 12 weeks after exposure (acute schistosomiasis, or Katayama fever)
A dry cough, headache and a widespread hives-like rash during that feverish phase
Tummy pain and diarrhoea, sometimes with blood, in the following weeks or months
Blood in the urine or discomfort passing water, months to years later with the bladder form
Rarely, weakness or numbness in the legs, or changes to your vision, if worms reach the spinal cord or brain: seek urgent care
Long term: scarring of the bladder or liver, repeated urine infections and, with the bladder form, possibly a raised risk of bladder cancer
FAQ
Schistosomiasis — frequently asked questions
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Trusted resources
Authoritative guidance on Schistosomiasis from leading public health bodies.
