Evaluation of indirect fluorescent antibody (IFA) test for kala-azar for diagnostic potential in endemic areas

An indirect fluorescent antibody (IFA) test using Leishmania donovani promastigote and amastigote antigens for diagnosis of kala-azar was evaluated in a kala-azar endemic area of Bihar, India. The test was found to be highly sensitive and specific using the promastigote antigen. It was positive in about 99% of parasitologically proven cases (n = 105), 89% of clinically suspected cases (n = 70) and all the sodium antimony gluconate (SAG) resistant cases (n = 80). None of the non-endemic control subjects (n = 40) or subjects infected with tuberculosis (n = 20), leprosy (n = 28), malaria (n = 20) and amoebiasis (n = 20) showed positive response. Only about 3% of the control subjects (n = 70) of the endemic area showed false positive response. Similar results were obtained with the amastigote antigen.