Schistosomiasis (Bilharzia)

What causes schistosomiasis?

Infection occurs when the parasite’s larvae penetrate a person’s skin during contact with infested water, often through fishing, swimming, bathing and washing clothes.

The lifecycle of schistosomiasis/bilharzia

Once inside the human body, schistosome larvae develop into adult worms and the eggs they lay can become trapped in the body’s tissues. Adult worms grow to approximately 1cm in length and live in blood vessels. Without treatment with anti-worm medication, the worms can keep laying eggs for several years.

Eggs can pass out of the body into water, through excreta. When this happens, they release tiny larvae that need to grow inside freshwater snails for a few weeks before they’re able to infect another person. This means it’s not possible to catch the infection directly from someone else who has it, but indirectly through contact with contaminated water.

Long-term complications of schistosomiasis

People who live with schistosomiasis for a long time without treatment can develop more serious health problems. This is also called “chronic schistosomiasis”.

Symptoms get worse in the parts of the body where the schistosoma eggs travel to, and cause infection. Chronic schistosomiasis can cause serious health problems in almost any area of the body, including the digestive, urinary, pulmonary and nervous systems.

Without treatment, schistosoma can cause permanent organ damage, shutdown, and even death.

Examples of long-term health complications of schistosomiasis include:

• Impact on the digestive system, such as abdominal pain and swelling, diarrhoea and blood in faeces
• Impact on nutritional outcomes, such as anaemia and stunting (short height-for-age)
• Urinary and bladder problems, like cystitis, contracted bladder and bladder cancer
• Reproductive problems, such as female genital schistosomiasis and infertility
• Problems with heart and lungs, including shortness of breath or coughing up blood
• Brain and nervous system issues, like headaches, weakness and numbness, dizziness or fits.

Schistosomiasis treatment

Schistosomiasis can usually be treated successfully with a short course of a medication called praziquantel, which kills the worms.

Steroid medication can also be used to help relieve the symptoms of acute schistosomiasis, or symptoms caused by damage to the brain or nervous system.

The medication is administered in our partner ministry of health programmes by local teachers and volunteers known as community drug distributors (CDDs).

Schistosomiasis is often treated alongside other neglected tropical diseases such as intestinal worms, lymphatic filariasis and river blindness.

More information about how we work and our strategic plan for 2018-25 is here.

Who is affected by schistosomiasis?

Schistosomiasis affects over 200 million people worldwide. The parasite is most commonly found in sub-Saharan Africa, but also lives in parts of South America, the Caribbean, the Middle East and Asia. Local outbreaks are possible where environmental conditions allow, as demonstrated recently by renewed schistosomiasis transmission in the Mediterranean.

Schistosomiasis mainly occurs in poorer communities that don’t have access to clean drinking water or adequate sanitation. It affects those who rely on use of infected surface water for their daily living needs such as drinking, cooking, cleaning and bathing, or their livelihoods.

The link between schistosomiasis and poverty

There is a clear link between schistosomiasis and poverty. Countries where 25% of people live on less than $1.90 per day also tend to have a moderate to high prevalence of schistosomiasis. Poorer countries are more likely to have a higher risk of schistosomiasis infection. Schistosomiasis is most prevalent in sub-Saharan African countries, which also tend to have weaker or inadequately-resourced public health services and basic water and sanitation infrastructure.

Schistosomiasis Prevention

There’s no vaccine for schistosomiasis, so it’s important that people are aware of the risks and have access to services such as safe water supply and sanitation to reduce exposure to contaminated water, and prevent contamination from taking place.

Poverty is both a cause and consequence of the poor health caused by schistosomiasis. In children, the disease can cause anaemia and stunted growth, and can affect their ability to learn and their future prospects. Many infected adults are unable to work or be fully productive due to fatigue and weakness, leading to economic hardship.

What Unlimit Health is doing

Since our foundation in 2002, we’ve helped establish programmes against parasitic worm infections in countries where none previously existed, and now support the delivery of millions of treatments each year through a strong partnership with ministries of health.

Our schistosomiasis treatment programmes specifically target school-age children and adults considered at risk, such as fishing communities, living in endemic regions. In areas with very high rates of infection, entire communities may be treated through mass drug administration. We also support non-drug-based practices such as water, sanitation and hygiene (WASH) initiatives.

In 2020-21, we supported ministries of health in Burundi, Côte d’Ivoire, Ethiopia, Liberia, Madagascar, Malawi, Niger, Sudan, Uganda and Zanzibar to deliver 63 million treatments for schistosomiasis and soil-transmitted helminths.

The work we still need to do

Estimates show that at least 251.4 million people required preventive treatment for schistosomiasis in 2021, out of which more than 75.3 million people were reported to have been treated.

With your support, even more people can be reached. Please make a donation today.