Leprosy reactions: the effect of gender and household contacts

Various host-related factors have been reported as relevant risk factors for leprosy reactions. To support a new hypothesis that an antigenic load in local tissues that is sufficient to trigger the immune response may come from an external supply of Mycobacterium leprae organisms, the prevalence of reactional leprosy was assessed against the number of household contacts. The number of contacts was ascertained at diagnosis in leprosy patients coming from an endemic area of Brazil. The prevalence of reactions (patients with reactions/total patients) was fitted by binomial regression and the risk difference (RD) was estimated with a semi-robust estimation of variance as a measure of effect. Five regression models were fitted. Model 1 included only the main exposure variable "number of household contacts"; model 2 included all four explanatory variables ("contacts", "fertile age", "number of skin lesions" and "bacillary index") that were found to be associated with the outcome upon univariate analysis; models 3-5 contained various combinations of three predictors. Male and female patients were analyzed separately. In females, household contacts were a significant predictor for leprosy reactions in model 1 [crude RD = 0.06; 95 percent confidence interval (CI) = 0.01; 0.12] and model 5 (RD = 0.05; CI = 0.02; 0.09), which included contacts, bacillary index and skin lesions as predictors. Other models were unsatisfactory because the joint presence of fertile age and bacillary index was a likely source of multicollinearity. No significant results were obtained for males. The likely interpretation of our findings might suggest that in female patients, leprosy reactions may be triggered by an external spreading of M. leprae by healthy carrier family members. The small number of observations is an obvious limitation of our study which requires larger confirmatory studies.

Epidemiological pattern of leprosy in an endemic area of North-East Brazil, 1996-2005: the supporting role of a Nongovernmental Organization / O perfil da hanseníase em uma área endêmica do nordeste do Brasil, 1996-2005: atividade de suporte de uma Organização Não Governamental

In an endemic area of North-East Brazil (the town of Picos, State of Piauí), a nongovernmental organization (NGO) supported the activity against leprosy in connection with governmental health organizations and local agents. The indicators of leprosy elimination were compared over time (within Picos) and across space (Picos versus Piauí). The case detection rate, above 8 per 10,000 people in the last two years of observation, increased over time in Picos (p=0.010). This finding could be due to active detection activities rather than expanding endemicity, as suggested by the reduction in leprosy in children (p=0.053) and the decrease in the proportion of new cases with grade 2 disability (p<0.001). These indicators showed a more favorable time trend in the city than in the State, suggesting that NGO activity was supportive in the battle towards leprosy control.

Para avaliar a atividade da sustentação fornecida por Organizações Não Governamentais (ONG)na luta contra a hanseníase, o perfil epidemiológico da doença em uma cidade é comparado ao perfil do todo Estado do Piauí. A tendência temporal da taxa de detecção é de aumento em Picos (p=0,010), e nos últimos dois anos de observação estava acima de 8 para 10.000 habitantes, duas vezes maior do que o limiar de hiperendemicidade (4 para 10.000). Como varia paralelamente com a redução da hanseníase nas crianças (p=0,053) e a diminuição da proporção de casos novos com grau 2 de incapacidade (p<0.001), o incremento no tempo da taxa de detecção pode ser atribuído mais à maior intensidade da atividade de detecção do que à expansão da endemicidade. Os indicadores de eliminação da hanseníase têm uma tendência no tempo mais favorável na cidade do que no Estado do Piauí, sugerindo que o ONG fosse útil na batalha para o controle da hanseníase.