Abstract
BackgroundThis study aimed to evaluate the risk factors associated with developing leprosy among the contacts of newly-diagnosed leprosy patients.Methodology/Principal FindingsA total of 6,158 contacts and 1,201 leprosy patients of the cohort who were diagnosed and treated at the Leprosy Laboratory of Fiocruz from 1987 to 2007 were included. The contact variables analyzed were sex; age; educational and income levels; blood relationship, if any, to the index case; household or non-household relationship; length of time of close association with the index case; receipt of bacillus Calmette-Guérin (BGG) vaccine and presence of BCG scar. Index cases variables included sex, age, educational level, family size, bacillary load, and disability grade. Multilevel logistic regression with random intercept was applied. Among the co-prevalent cases, the leprosy-related variables that remained associated with leprosy included type of household contact, [odds ratio (OR) = 1.33, 95% confidence interval (CI): 1.02, 1.73] and consanguinity with the index case, (OR = 1.89, 95% CI: 1.42–2.51). With respect to the index case variables, the factors associated with leprosy among contacts included up to 4 years of schooling and 4 to 10 years of schooling (OR = 2.72, 95% CI: 1.54–4.79 and 2.40, 95% CI: 1.30–4.42, respectively) and bacillary load, which increased the chance of leprosy among multibacillary contacts for those with a bacillary index of one to three and greater than three (OR = 1.79, 95% CI: 1.19–2.17 and OR: 4.07–95% CI: 2.73, 6.09), respectively. Among incident cases, household exposure was associated with leprosy (OR = 1.96, 95% CI: 1.29–2.98), compared with non-household exposure. Among the index case risk factors, an elevated bacillary load was the only variable associated with leprosy in the contacts.Conclusions/SignificanceBiological and social factors appear to be associated with leprosy among co-prevalent cases, whereas the factors related to the infectious load and proximity with the index case were associated with leprosy that appeared in the incident cases during follow-up.
Highlights
The primary aim of all disease control measures is to reduce the incidence, prevalence, morbidity and/or mortality rates to the lowest level possible in a given population
Leprosy is an infectious disease that can lead to physical disabilities, social stigma, and great hardship
Knowledge of the risk factors for leprosy can facilitate early detection; our study aimed to investigate the factors presented by leprosy patients and their contacts, who are considered at highest risk of contracting the disease
Summary
The primary aim of all disease control measures is to reduce the incidence, prevalence, morbidity and/or mortality rates to the lowest level possible in a given population. In 2007, the Brazilian Ministry of Health adopted new case detection rates for all ages and for children under 15 years of age as indicators of the effectiveness of leprosy control measures in the country. Because detection of leprosy in those under 15 years of age is considered indicative of recent Mycobacterium leprae (ML) transmission, evaluating these cases for epidemiologic markers was especially important [2]. In early 2009, the global prevalence of leprosy was approximately 213,000 cases; the annual detection rate of leprosy worldwide has declined. In Brazil, in 2008, there were 38,914 new leprosy cases detected. The detection rates in Rio de Janeiro for children less than 15 years old in the period 2001–2008 had very high ratings (6.00/100,000 population to 2.69/100,000 population). This study aimed to evaluate the risk factors associated with developing leprosy among the contacts of newlydiagnosed leprosy patients
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