Schistosomiasis (Bilharzia)

Factsheet

Key Facts

• Schistosomiasis is an acute and chronic disease caused by parasitic worms.
• People are infected during routine agricultural, domestic, occupational and recreational activities which expose them to infested water.
• Lack of hygiene and certain play habits of school-aged children such as swimming or fishing in infested water make them especially vulnerable to infection.
• Estimates show that at least 253.7 million people required preventive treatment for schistosomiasis in 2024, out of which more than 100.5 million people were reported to have been treated.
• Schistosomiasis control focuses on reducing disease through periodic, large-scale population treatment with praziquantel; a more comprehensive approach including ensuing access to safe drinking water, adequate sanitation, behaviour change interventions, veterinary public health and snail control can also reduce transmission.

Schistosomiasis is an acute and chronic parasitic disease caused by blood flukes (trematode worms) of the genus Schistosoma. Estimates show that at least 253.7 million people required preventive treatment in 2024. Preventive treatment, which should be repeated over a number of years, will reduce and prevent morbidity. Schistosomiasis transmission has been reported from 79 countries. Transmission of Schistosoma haematobium has been confirmed in Cabo Verde, a country which was not previously considered endemic. However, preventive chemotherapy for schistosomiasis, where people and communities are targeted for large-scale treatment, is only required in 50 endemic countries with moderate-to-high transmission.

Schistosomiasis, or bilharzia, is a disease that is caused by parasitic worms. Infestation occurs when parasites that are released by certain types of freshwater snails come in contact with the skin or are ingested.

It is estimated that at least 90% of those requiring treatment for schistosomiasis live in the African Region. Schistosomiasis is the second most socioeconomically devastating parasitic disease after malaria.

The symptoms of schistosomiasis include a rash or itchy skin that is followed by fever, cough and chills. In urinary schistosomiasis, there is progressive damage to the bladder, ureters and kidneys. The urinary form of schistosomiasis is also associated with an increased risk for bladder cancer in adults. In intestinal schistosomiasis, there is progressive enlargement of the liver and spleen and intestinal damage.

It’s common for schistosoma parasites to break through the skin of persons bathing, swimming or fishing in contaminated fresh water. Women doing domestic chores in infested water, such as washing clothes are also at risk. Poor hygiene and play habits make children especially vulnerable to the infection.

It’s also important to drink safe water. Drinking water can come from rivers, lakes and reservoirs and should be boiled for at least 1 minute to kill any parasites.