Bilhar

Bilhar, commonly used to refer to bilharziasis or schistosomiasis, is a parasitic disease caused by blood flukes of the genus Schistosoma. The term bilharziasis honors Theodor Bilharz, who described the condition in Egypt in the 1850s. The disease affects humans in tropical and subtropical regions and remains a major public health problem in some areas.

Transmission occurs when cercariae in freshwater penetrate skin during contact with contaminated water. The larvae mature into adult worms in the venous systems of the intestine or bladder, where they produce eggs. Eggs may be shed in feces or urine, but many become lodged in tissues, triggering inflammation and progressive organ damage. Snails act as intermediate hosts in the life cycle.

Clinical manifestations vary by species. Acute symptoms (Katayama fever) include fever, cough, and eosinophilia. Chronic infection can cause intestinal disease (abdominal pain, diarrhea, malnutrition), hepatosplenic involvement with fibrosis and portal hypertension, or urinary disease (hematuria, dysuria) and bladder pathology that increases cancer risk.

Diagnosis relies on detecting eggs in stool or urine, supported by serology, antigen tests, or PCR. Imaging may assess organ damage. The drug of choice is praziquantel, given in species-appropriate doses; oxamniquine has been used in some settings. Prevention emphasizes safe water, sanitation, snail control, and mass drug administration in endemic areas.

Schistosomiasis affects hundreds of millions worldwide, predominantly in sub-Saharan Africa, the Middle East, and parts of Asia and the Americas. The term and disease trace to Theodor Bilharz, whose work linked human infection to freshwater snails.