BACKGROUND: The transmission of leprosy has issues not understood due to the long incubation period and the fact that only a few of the exposed subjects get sick. Besides the exposure to the M. leprae, genetic susceptibility is an important risk fact for the disease. OBJECTIVE: To study the transmission of leprosy in family clusters in an endemic urban area in the second district of Duque de Caxias, Rio de Janeiro, Brazil. METHODS: Twenty families, who presented more than one case of the disease in a period of ten years, were studied, starting from 20 index cases. The patients were visited in their houses, for dermatologic and peripheric nerves examination. RESULTS: There was a predominance of the disease among consanguineous contacts (69/75). The risk of getting leprosy among those who were consanguineous was 2.8 times higher than among those who were not consanguineous. Only 3 partners were sick among the 6 non-consanguineous, although only 14 offsprings were affected. In two families the disease was restricted to one generation, in five the disease was present in three generations and in thirteen there were two generations of persons with leprosy. CONCLUSIONS: Although other risk factors, not focused in this paper, are involved in the transmission of leprosy, consanguinity shows a positive association and confirms the need of the epidemilogic surveillence of the relatives that are close to the leprosy patients. These are preliminary outcomes of a 70 families study. The inclusion of more families and the study of the genetic polymorphism will provide a better approach in this complex issue.
Household contacts; Leprosy; Genetic susceptibility
