Familial aggregation of mucosal leishmaniasis in northeast Brazil.

To evaluate whether familial clustering occurs in mucosal leishmaniasis (ML), patients with ML (index cases) were randomly selected from medical records at a health post in an endemic area for Leishmania braziliensis infection. Control individuals (index controls) matched by age, gender, and place of residence to index cases were selected. Family members of index cases and controls were compared with respect to environmental factors and the incidence of cutaneous leishmaniasis (CL) and ML. Delayed type hypersensitivity test (DTH) to Leishmania antigen was tested in selected families. Among 289 members of 46 families enrolled, significant differences were found in the frequencies of CL (37% versus 20%) and ML (5% versus 0) in case versus control families, respectively. Families with 2 cases of ML had a higher frequency (29.6%) of DTH-positive individuals than control families (9.4%). These data demonstrate familial clustering of CL, ML, and positive DTH skin tests in an area endemic for L. braziliensis infection.