Evaluation of direct agglutination test (DAT) as an immunodiagnostic tool for diagnosis of visceral leishmaniasis in Nepal

Abstract

Before field application of the direct agglutination test (DAT) for leishmaniasis, it was assessed as a diagnostic tool. Fifteen confirmed visceral leishmaniasis cases (bone marrow aspiration positive), 120 tuberculosis, 58 leprosy, 15 malaria 26 intestinal parasitic infection cases, 24 endemic healthy controls from adjacent to the study area, and 18 controls from Kathmandu (who had never visited the VL endemic areas) were tested for anti-leishmanial antibody agglutination titers. Two of the tuberculosis cases were positive for anti-leishmanial agglutinating antibodies at 1:800. All the visceral leishmaniasis confirmed cases were reactive to anti-leishmanial antibody at ≥1:3,200. Other specimens were negative for serology. The sensitivity of the direct agglutination test was 100% and the specificity was 99.2%. The direct agglutination test had positive and negative predictive values of 100% and 99.2% respectively. The direct agglutination test has been found to be simple, rapid, reliable, economic, safe and adaptable to micro-techniques using microliter plates. It is specific and sensitive. The direct agglutination test is simple enough for it to be performed in a field laboratory.