Kinship and Leprosy in the Contacts of Leprosy Patients: Cohort at the Souza Araújo Outpatient Clinic, Rio de Janeiro, RJ, 1987–2010

Abstract

A broad variety of factors have been associated with leprosy among contacts, including socioeconomic, epidemiological, and genetic characteristics. Data from 7,174 contacts of leprosy patients from a leprosy outpatient clinic in Rio de Janeiro, Brazil, 1987–2010, were analyzed to investigate the effects of kinship, individual, and contextual factors on leprosy. Multivariate analyses were performed using a robust estimation method. In the prevalence analysis, close kinship (sibling OR = 2.75, offspring OR = 2.00, and other relatives OR = 1.70), socioeconomic factors, and the duration of exposure to the bacillus were associated to leprosy. In the incidence analysis, significant risks were found for all categories of kinship (parents RR = 10.93, spouse, boyfriend/girlfriend, and bride/groom RR = 7.53, sibling RR = 7.03, offspring RR = 5.34, and other relatives RR = 3.71). Once the treatment of the index case was initiated, other factors lost their significance, and the index case bacteriological index and BCG (Bacillus Calmette-Guérin vaccine) protection had a greater impact. Our findings suggested that both genetic susceptibility and physical exposure play an important role in the epidemiology of leprosy, but it was not possible establishing the role of genetic factor. Analyses of other factors related to the genotype of individuals, such as genetic polymorphisms, are needed.

Socioeconomic factors related to leprosy: an integrative literature review

“…Regarding the incidence and prevalence of leprosy, among inside and outside the person's house contacts, of the cases diagnosed in a referral service (15) , the prevalence was associated with black/brown skin color; years of study less than four, living in the same house, having more than five years of living with the index case, and presenting bacterial index >3. The incidence was also associated with black/brown color, bacterial index >0; and the BCG vaccine showed a protective effect on both the incidence and the prevalence of leprosy among the contacts.…”

Pauci- and Multibacillary Leprosy: Two Distinct, Genetically Neglected Diseases

“…Therefore, we based our approach on more general epidemiological studies of leprosy per se that included information on MB and PB forms. The vast majority of recent epidemiological studies focused on the contacts of an index leprosy case to identify risk factors for the occurrence of secondary cases [ 17 – 21 ]. In this setting, subgroup analysis of clinical forms is not very powerful, given the low number of such secondary cases: indeed, the detection rate of new cases is often less than 1% after 4 years of follow-up, requiring 10,000 contacts to ultimately study 100 secondary leprosy cases [ 18 , 19 ].…”

“…Numerous studies have established that among close contacts of index cases (e.g., individuals living in the same house or sharing the same bed as the case), those biologically related to the index case are significantly more at risk of developing leprosy per se [ 17 , 18 , 21 ]. Intriguingly, no study has focused specifically on the subtype of leprosy developed by these secondary cases according to their demographics (age, sex, etc.,) or those of the index case, further substantiating that these phenotypes are 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).…”