The frequency of asymptomatic infection among relatives and neighbors of
cases of visceral leishmaniasis (VL) was compared and characterization of
the immunological response in these subjects was performed. Cases were
from a new endemic area, close to the beach and near Salvador, capital of
the State of Bahia, Brazil. The characterization of asymptomatic infection
was made using a skin reaction test and detection of antibody to
Leishmania chagasi by the ELISA test. To characterize the immunological
response of these subjects with asymptomatic L. chagasi infection the
cytokines profile and the lymphoproliferative response were determined
after stimulation of lymphocytes by L. chagasi antigen. There was no
difference in the frequency of L. chagasi infection in relatives (45%) and
in neighbors (27%) of cases of VL (P}0.05). The immunological response from
these subjects was characterized by high production of IFN-gamma and a low
production of IL-10 and a good lymphoproliferative response to L. chagasi
antigen.
