Kala-Azar, also known as visceral leishmaniasis, is a parasitic disease caused by the Leishmania parasite, transmitted through the bite of infected sandflies. It primarily affects the internal organs, particularly the spleen and liver, leading to symptoms such as fever, weight loss, and anemia. If left untreated, it can be fatal. The disease is prevalent in tropical and subtropical regions, including parts of India, Bangladesh, and Sudan. Diagnosis typically involves blood tests or bone marrow examination, while treatment includes medications like antimonials or liposomal amphotericin B. Early detection and treatment are crucial for recovery.