schistosomozn

Schistosomiasis, also known as bilharzia, is a parasitic disease caused by infection with blood flukes of the genus *Schistosoma*. These flatworms infect approximately 250 million people worldwide, primarily in tropical and subtropical regions, particularly in sub-Saharan Africa, parts of South America, the Caribbean, and Asia. The disease poses a significant public health burden, contributing to morbidity and mortality in endemic areas.

The life cycle of *Schistosoma* involves both human hosts and freshwater snails as intermediate hosts. Humans become infected when skin contact occurs with contaminated water containing the parasite’s free-swimming larval stage, known as cercariae. Once inside the body, cercariae lose their tails and transform into schistosomomulae, which migrate through the bloodstream to specific organs depending on the species. For example, *Schistosoma mansoni* and *S. japonicum* primarily affect the intestines and liver, while *S. haematobium* targets the urinary bladder and kidneys.

Symptoms of schistosomiasis vary depending on the species and the stage of infection. Acute infection may cause a rash, fever, chills, and muscle aches, often referred to as Katayama fever. Chronic infection can lead to severe complications, including organ damage, anemia, bladder cancer (in the case of *S. haematobium*), and liver fibrosis or portal hypertension. Children and pregnant women are particularly vulnerable to severe outcomes.

Diagnosis typically involves microscopic examination of urine or stool samples to detect parasite eggs, though more advanced techniques such as serological tests are also used. Treatment primarily relies on a single oral dose of praziquantel, which is highly effective against all species of *Schistosoma*. Prevention strategies include improving sanitation, safe water supplies, and snail control programs, as eliminating the intermediate host reduces transmission.

Control efforts are coordinated through global health initiatives, such as the World Health Organization’s (WHO) Schistosomiasis Control Programme, which emphasizes mass drug administration in high-burden areas. Research continues to focus on vaccine development, improved diagnostics, and integrated approaches to reduce the disease’s impact.