Neglected Tropical Diseases: Schistosomiasis

Did you know that some parasitic worms can infect you just by swimming or bathing in contaminated water? These tiny worms are called schistosomes, and they cause a disease called schistosomiasis. Schistosomiasis does not usually kill people, but it can cause many serious problems in the long term. That is why it is important to try to prevent and treat the disease!


Infection does not happen directly between people. Instead, worm eggs are released into water through the faeces (poo) or urine (pee) of infected people. These eggs then hatch into larvae (baby worms), which infect snails living in the water. Once in the snail, the larvae grow for 2-4 weeks. They then leave the snails, go back into water, and swim until they reach human or another mammal’s (for example, a cow’s) skin. They enter the human or mammal through the skin. After 4-9 weeks, the worms begin making more eggs in the human body. Some of these eggs remain in the body while the rest of the eggs are released through the faeces or urine of the person, starting the cycle again.


It is possible to be infected and not feel sick for months or years. There are both short-term and long-term harmful effects from schistosomiasis.

Short-term effects (few weeks after infection):
-fever (high body temperature)
-small itchy, red bumps on skin
-diarrhoea (runny or watery faeces)
-stomach, muscle, or joint pain

These short-term effects will often get better by themselves after a few weeks. It is still very important to get treatment if possible! That is because the worms can live in humans for years, leading to long-term problems.

Long-term effects (months or years after infection):
-poor nutrition, stomach pain, stomach swelling, diarrhoea, blood in faeces (poo)
-pain when urinating (peeing), needing to urinate often, and blood in urine (pee)
-coughing, coughing up blood
-headaches, dizziness, numbness, weakness, seizures (fits)


Schistosome worms live in fresh water, such as lakes, rivers, and ponds. They do not live in the ocean. The eggs and larvae are very small and cannot be seen without special equipment.

Here are a few ways to prevent infection:
-Avoid swimming or washing in contaminated water if possible. Swimming in the ocean or in chlorinated swimming pools is fine.
-Wear waterproof boots and trousers if you need to work or pass through contaminated water
-Boil water for at least a minute before drinking – this will also help kill other harmful bacteria, viruses, and parasites! If boiling is difficult, filter water with a clean cloth or other filter.
-Boil water for at least a minute before bathing, and let it cool. If boiling is difficult, store the water for 1-2 days before using it for bathing.
-Try to prevent humans and livestock from defecating (pooing) or urinating near water sources.

There are safe and effective medicines to treat schistosomiasis. One of these medicines is called praziquantel. This medicine is more effective after the worms have grown a bit, so treatment may be delayed or repeated a few weeks after infection. Remember to follow instructions for how much and how often to take the medicine, to make sure all the worms are killed.

Since schistosome worms need water to grow and infect people, good sanitation and water habits from the entire community will help to get rid of this worm!



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