Leprosy among Patient Contacts: A Multilevel Study of Risk Factors

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.

Unveiling healthy carriers and subclinical infections among household contacts of leprosy patients who play potential roles in the disease chain of transmission

“…HHCs comprise a recognisable group of individuals with a high risk of disease, as they live in close proximity to a source of infection (Sales et al 2011). Their participation in the dissemination and spread of M. leprae to susceptible persons in endemic communities cannot be neglected.…”

Presence of Mycobacterium leprae DNA and PGL-1 antigen in household contacts of leprosy patients from a hyperendemic area in Brazil

“…Several other reports have observed a high concentration of leprosy cases in individual households (Sales et al, 2011;Düppre et al, 2012;Dos Santos et al, 2013) and extra-domiciliary contacts (Moura et al, 2013). This indicates the necessity of preventive measures against leprosy that are efficient in hyperendemic areas.…”

“…The presence of IgM and M. leprae DNA in the household contact samples does not indicate illness, as there are biological and social factors that determine the development of leprosy (Sales et al, 2011;Dos Santos et al, 2013). Few studies have demonstrated association between DNA positivity and leprosy risk (Reis et al, 2014).…”

“…The upper airways of untreated patients are the primary site of bacillus entrance and exit. Thus, household contacts of infected individuals are at the highest risk of becoming ill in the short term Sales et al, 2011). According to the World Health Organization (2011), active searching and monitoring of patients' household contacts are the most effective strategies for limiting the spread of leprosy (Smith and Aerts, 2014).…”

Molluscum Contagiosum–Like Lesions in Histoid Leprosy in a 35-Year-Old Indian male

“…Skin and nasal epithelia of individuals with untreated multibacillary leprosy are a potential shedding ground of Mycobacterium leprae into the environment. This assumes importance in view of the fact that many undiagnosed histoid cases with a high bacillary index can contribute to transmission in endemic areas through the skin 8 A high index of suspicion is required in diagnosing such cases for prompt treatment as histoid leprosy could serve as a reservoir of leprosy and a source of new cases especially in the post leprosy elimination era. …”