key points
- Bilharzia is a parasitic disease caused by worms called schistosomes.
- It is transmitted through contact with contaminated fresh water, mainly in tropical regions.
- The disease can progress to chronic forms that cause urinary, digestive or hepatic complications.
- The treatment is simple and effective when administered early.
- Prevention relies on access to drinking water, sanitation and avoidance of hazardous freshwater sources.
Disease
Bilharziasis, also called schistosomiasis, is a parasitic disease caused by flatworms of the genus SchistosomaThe main species responsible for human diseases are Schistosoma haematobium, S. mansoni et S. japonicumThe parasite has a complex life cycle involving an intermediate host, a freshwater mollusk. The larvae released into the water actively penetrate human skin upon contact with contaminated water. The adult worms then develop in the blood vessels, where they produce eggs that cause inflammation and damage to the affected organs. Schistosomiasis is not contagious from person to person.
Schistosomiasis worldwide
Schistosomiasis is one of the most widespread parasitic diseases in the world. It primarily affects tropical and subtropical regions, particularly sub-Saharan Africa, which accounts for the majority of cases. The disease is also present in South America, the Middle East, and Asia. It is estimated that more than 200 million people are infected worldwide, and several hundred million live in at-risk areas. Children and populations living in precarious conditions are the most vulnerable due to frequent contact with contaminated freshwater. In non-endemic countries, schistosomiasis is observed as imported cases, particularly among migrants, travelers, and people who have stayed in endemic areas.
The clinic
The disease often progresses in several phases. A skin reaction (itching, rash) may appear at the point of larval penetration. A few weeks later, some patients experience an acute phase, characterized by fever, fatigue, muscle pain, cough, or digestive problems. Without treatment, schistosomiasis can become chronic. Depending on the species involved, it can lead to urinary tract infections (blood in the urine, urinary problems), digestive issues (chronic diarrhea, abdominal pain), or liver damage (fibrosis, portal hypertension). Complications can be serious and debilitating, but they are preventable with early diagnosis and treatment.
The diagnosis
The diagnosis of schistosomiasis relies on identifying a history of travel to or exposure to freshwater in an endemic area, along with compatible clinical signs. It is confirmed by detecting schistosomes in urine or stool, depending on the form of the disease. Serological tests may be used, particularly in travelers or in cases of recent infection. Further examinations may be necessary to assess organ involvement and potential complications.
Symptoms of Schistosomiasis
The symptoms of schistosomiasis are:
- Dermatitis: small red spots, itching, hives (contamination phase).
- Acute Katayama Fever: high fever associated with a dry cough, muscle aches and fatigue.
- Abdominal pain, diarrhea, blood in the urine, and frequent urination (early chronic phase)
- Chronic inflammation of the liver and kidneys (late chronic state phase).
The treatment
Treatment for schistosomiasis relies on an antiparasitic drug, praziquantel, which is effective against the main species of schistosomes. The treatment is generally well tolerated and administered in one or more doses, as recommended. It eliminates adult parasites and prevents the development of chronic and complicated forms. Medical follow-up may be necessary to verify the effectiveness of the treatment and monitor for complications.
Prevention
Prevention of schistosomiasis relies primarily on reducing exposure to contaminated freshwater in endemic areas. Swimming, washing, and other water activities in at-risk lakes, rivers, and canals are strongly discouraged. Improving access to safe drinking water and sanitation, as well as controlling intermediate host mollusks, are essential community-wide measures. Travelers should receive appropriate information before departure. In the event of accidental exposure to freshwater in an endemic area, medical screening is recommended, even in the absence of symptoms.
FAQ
La bilharzia It is transmitted through contact with contaminated freshwater in endemic areas. The parasite's larvae, released by freshwater mollusks, actively penetrate the skin. The disease is not transmitted from person to person.
The first signs may include itching or a rash at the point of contact with the water. An acute phase may occur a few weeks later, characterized by fever, fatigue, muscle pain, or digestive problems. In its chronic stage, the disease can cause urinary, digestive, or hepatic involvement, depending on the species involved.
People living or staying in tropical or subtropical areas and who have contact with fresh water (swimming, washing, work activities) are the most exposed. Children and people living in poverty are particularly at risk.
Diagnosis is based on exposure to fresh water in an endemic area and the detection of schistosomes in urine or stool. Serological tests may be used, particularly in travelers or in recent cases, as well as further examinations to assess complications.
Treatment relies on praziquantel, an antiparasitic drug effective against the main species of schistosomes. When administered early, it helps prevent chronic forms and complications. Prevention involves avoiding high-risk freshwater sources, improving access to safe drinking water and sanitation, and informing travelers before departure.
