Immunological studies were done in 48 subjects with a past history of visceral leishmaniasis and in 6 patients during the active phase of the disease and shortly after treatment. Antibody titers determined by immunofluorescence antibody test (IFA) or ELISA were positive in 32 (67%) of the 48 persons that had visceral leishmaniasis in the past. The mean antibody titer by the IFA in the 6 patients with active visceral leishmaniasis was 9536 ± 7169 and thymidine uptake in the lymphocyte blastogenesis assay was 323 ± 24. After treatment (3 and 6 months) antibody titers had fallen only in 3 of the 6 patients and a restoration of the lymphocyte proliferative response wasobserved (11909 ±5637). These data demonstrated that there is no genetic inability of the host who acquire visceral leishmaniasis to develop a cellular immune response to leishmania antigen. Moreover, the longterm persistence of high antibody titers following therapy suggests that the parasite may stay in the host for long time even after apparent clinical cure of the infection.
Leishmaniasis; Visceral leishmaniasis; Kala-azar; Humoral immunity; Cellular immunity