[Persistence of leprosy in household social networks: overlapping cases and vulnerability in endemic regions in Brazil].

The study sought to analyze the magnitude of occurrence and the sociodemographic, economic and clinical profiles of leprosy associated with household social networks (HSN), with disease overlap in cities from the states of Bahia, Piauí and Rondônia, Brazil, from 2001 to 2014. This is a cross-sectional study using primary and secondary data regarding new cases of leprosy notified to the Brazilian Information System for Notifiable Diseases (SINAN, in Portuguese) residing in the cities. We applied a standardized instrument to the new cases and reviewed data from charts and from SINAN. Of a total of 1,032 (29.6%) assessed cases, 538 (52.1%) had more than one case in their HSN. There were larger frequencies of female sex (292; 54.3%), age between 41 and 60 years (240; 44.6%), primary education (272; 50.6%), income lower than the minimum wage (265; 49.3%) and living with 5 or more people (265; 49.3%). The overlap of cases in the HSN was associated in the multivariate analysis with residing in cities in the state of Rondônia (PR = 1.23; 95%CI: 1.07-1.43; p = 0.003), as well as living with 3 to 4 people in the same household (PR = 1.66; 95%CI: 1.11-2.49; p = 0.014) and having leprosy reaction (PR = 1.31; 95%CI: 0.99-1.70; p = 0.050). Case repetition within the same HSN is a frequent event in the situations we studied. Its occurrence must be considered as a sentinel indicator of greater epidemiological severity in primary health care surveillance. We highlight the vulnerability of affected families.