Schistosomiasis: the freshwater risk worth knowing before you travel
Also called bilharzia, this one isn't about mosquitoes or a jab — it's about which water you go in. Call into Davyhulme Pharmacy and we'll explain where to be careful and how to keep yourself clear of it.
Schistosomiasis, which you might hear called bilharzia, is an infection caused by tiny parasitic worms that live in fresh water in certain parts of the world. It's a little different from most of the things we cover at the clinic: there's no vaccine and no tablet you can take in advance, and you don't catch it from a bite or from food. Instead, the parasite passes straight through your skin when you're in contaminated fresh water — so the whole of prevention comes down to being water-aware on your trip.
It catches a lot of travellers by surprise, because it's often the relaxing bits of a holiday that carry the risk — a dip in a lake, a paddle in a river, a go on a rope swing. We see plenty of people heading off from Manchester Airport on African safaris and adventure trips who simply haven't been told about it. A quick word before you go means you'll know which water to steer clear of, and what to do if you do end up taking a splash.
Who should be careful
Anyone travelling to sub-Saharan Africa, especially around freshwater lakes and rivers such as Lake Malawi, Lake Victoria and the River Nile
Adventure travellers, gap-year students, volunteers and aid workers who are likely to swim, wade, raft or wash in fresh water
Families on safari and longer-stay travellers, where the odds of some freshwater contact over a trip add up
What it is and how you pick it up
Schistosomiasis is caused by parasitic flatworms called schistosomes. Their life cycle runs through particular freshwater snails: the snails release a microscopic larval form of the worm into the water, and if that water touches your skin, the larvae can burrow straight in — you don't have to swallow anything or be bitten. That means any skin contact with infested fresh water counts: swimming, wading, paddling, washing, or even crossing a stream on foot. The good news is that it can't spread from person to person, and the water that matters is fresh water only.
Which water is risky and which isn't
The risk is fresh water in affected regions — lakes, rivers, ponds, dams, irrigation channels and slow-moving streams, particularly where it's warm and there are reedy, snail-friendly edges. The sea is not a risk, and properly chlorinated swimming pools are considered safe, as is bottled or boiled water for washing. You can't tell by looking whether a lake or river is affected — water that seems crystal-clear can still carry the parasite — so in a known risk area the safe assumption is to treat all fresh water as suspect unless you've been clearly told otherwise.
Where in the world it's found
By a long way the biggest burden is in sub-Saharan Africa, and famous spots like Lake Malawi and Lake Victoria are classic places travellers get caught out. It's also present in parts of the Middle East, South-East Asia, the Caribbean and South America, including pockets of the Nile valley and some areas around the Mekong. The picture varies enormously from place to place, so we'll look up the current TravelHealthPro (NaTHNaC) guidance for your exact destination when you come in, rather than going on a rough idea of a whole country.
How to keep yourself safe
Because there's nothing to take beforehand, avoiding freshwater contact is the whole game — and it's very effective. In a risk area, don't swim, paddle, wade or wash in fresh water; stick to the sea, a chlorinated pool, or water that's been boiled or treated. If you must cross water or get unexpectedly soaked, drying yourself off briskly with a towel afterwards may help, though it's not a reliable safeguard on its own. Water for washing or bathing is safest if it's been heated to a rolling boil and left to cool, or stored snail-free for a couple of days. We're happy to talk through the practical side for your particular trip in the pharmacy.
Symptoms and getting checked afterwards
Many people have no symptoms at all early on, which is part of why it slips under the radar. Some get an itchy rash where the parasite entered (sometimes called swimmer's itch) within hours or days, and a few develop a feverish illness a few weeks later — fever, cough, aches and tiredness — known as Katayama fever. Left untreated for years it can quietly affect the bladder, bowel or other organs. If you've had any freshwater contact in a risk area, it's worth mentioning to your GP even if you feel completely fine — a blood test some weeks after you get home can pick it up, and it's straightforward to treat with a medicine called praziquantel. Always tell any doctor where you've travelled.
Frequently asked questions
No — there's no vaccine, and nothing you can take in advance to stop you getting it. Prevention is entirely about avoiding contact with fresh water in affected areas. The good news is that if you do pick it up, it's treatable with a medicine called praziquantel, so the plan is to avoid the water where you can and get checked afterwards if you've had any contact.
Sea swimming is fine — the parasite needs fresh water, so salt water isn't a risk — and properly chlorinated pools are considered safe too. It's lakes, rivers, ponds and similar fresh water in affected regions you want to stay out of. Tell us where you're going and we'll let you know whether it's somewhere to be careful.
Try not to panic; plenty of people are fine. Drying off thoroughly afterwards may help a little, but the important step is to get checked once you're home. A blood test a few weeks after exposure can detect it, and treatment with praziquantel is simple and effective. Mention the freshwater contact to your GP even if you feel perfectly well.
Often there are no early symptoms at all. Some people get an itchy rash soon after, and a few develop a feverish illness — fever, cough, aches and tiredness — a few weeks later. Because it can be silent, the safest approach after freshwater contact in a risk area is to get tested rather than wait for symptoms. Always tell the doctor where you've travelled.
Sub-Saharan Africa carries by far the most risk, including well-known spots like Lake Malawi and Lake Victoria, but it also occurs in parts of the Middle East, South-East Asia, South America and the Caribbean. The detail varies a lot by location, so we check the current TravelHealthPro guidance for your specific destination when you come in.
Absolutely — it's a regular part of our travel appointments for people heading off on safaris and adventure trips from across Trafford. We'll go over the freshwater risk for your route, explain how to avoid it, and tell you what to look out for afterwards. Call Davyhulme Pharmacy on 0161 748 3016 to book in.
This information is grounded in NHS, TravelHealthPro (NaTHNaC) and UKHSA guidance and is for general information only — not a substitute for a personal consultation. Your suitability is assessed by our pharmacist before any vaccination.
Heading somewhere with a freshwater risk?
Book a travel health chat at Davyhulme Pharmacy in Urmston and we'll tailor the schistosomiasis advice to exactly where your trip takes you.