Leprosy among schoolchildren in the Amazon region: A cross-sectional study of active search and possible source of infection by contact tracing

Abstract

BackgroundThe high rate of leprosy cases among children under 15 years of age in Brazil indicates ongoing transmission within the community. The identification of the new leprosy cases among contacts can help identify the source of infection and interrupt the transmission chain. This study aims to determine the detection rate of previously undiagnosed cases of leprosy among schoolchildren who are under 15 years of age living in Manaus, Amazonas, Brazil, and their possible source of infection by contact tracing.Methodology/Principal findingsThis was a school-based, cross-sectional study in which the identification of active leprosy cases was conducted in 277 out of 622 randomly selected public schools in Manaus, Amazonas, Brazil. Suspected cases of leprosy were referred to the Alfredo da Matta Foundation, a reference center for leprosy in Manaus. A total of 34,547 schoolchildren were examined, and 40 new leprosy cases were diagnosed. Among new cases, 57.5% were males, and 80.0% demonstrated paucibacillary leprosy. A total of 196 of 206 registered contacts were screened, and 52.5% of the newly diagnosed children’s cases had at least one positive household contact. In these contacts, grandparents (52.4%) were the most common co-prevalent cases, while 14.3% were uncles, 9.5% were parents and 9.5% were granduncles. Seven contacts (5.0%), including four siblings of child patients were newly diagnosed. Our data indicate that the prevalence is 11.58 per 10,000, which is 17 times higher than the registered rate.Conclusions/SignificanceThis study suggests that the detection rate of leprosy among schoolchildren may have remained unchanged over the past thirty years. It also indicates that that active case finding is necessary for reaching the World Health Organization’s goals of zero detection among children, especially in endemic areas where the prevalence of leprosy is obscure. Moreover, we assert that all children must have their household contacts examined in order to identify the possible source of infection and interrupt the disease’s transmission. Novel strategies to reinforce contact tracing associated with large-scale strategies of chemo- and immune-prophylaxis should be expanded to prevent the perpetuation of the disease cycle.

Incidence of and Factors Associated With Leprosy Among Household Contacts of Patients With Leprosy in Brazil

“…20,21 Similar to our findings, previous research has reported higher odds of leprosy detection among contacts who are older 5,22,23 and male. 2 In this study, we found lower leprosy detection among contacts with lower educational levels. However, it is plausible that after a primary leprosy case in the household, contacts with education beyond the preschool level may have had improved leprosy knowledge, increased health-seeking behavior, and/or better access to health services that may have enhanced their case detection rates.…”

“…1 Current evidence suggests that, within these settings, household contacts of existing patients with leprosy are at high risk for developing leprosy. [2][3][4] The increased incidence of leprosy in household contacts is likely associated with a combination of increased exposure to infectious cases (eg, contacts of patients with multibacillary leprosy have a 5to 10-times greater risk of developing leprosy than the general population 4,5 ) and the sharing of social risk factors within a given family (eg, lower familial income and unfavorable household living conditions). [5][6][7][8] To enhance understanding of household leprosy transmission, this study used linked data from the 100 Million Brazilian Cohort to estimate the incidence of leprosy among household contacts of patients with leprosy and to compare the odds of leprosy detection among contacts by potential clinical, geographic, and socioeconomic risk factors.…”

Epidemiological and space aspects of the schools of the National Leprosy Campaign: the case of Sobral – Ceará, Brazil

“…If the child has contact with cases of leprosy in the environment outside the home is four times more likely to develop leprosy, although the development of the disease depends on the relationship of the bacillus and host 15,21,22 . In an active search campaign of new leprosy cases in Manaus (2018) were detected 40 new cases of leprosy in schoolchildren, 21 of whom had household contacts of leprosy transmission sources, and 95.2% had family contact with someone who had or has leprosy 23 .…”

Características epidemiológicas da hanseníase nos idosos e comparação com outros grupos etários, Brasil (2016-2018)

“…Evidenciou-se ainda que apenas 4,5% dos idosos foram detectados pelo exame de contatos, e que para os demais grupos etários este modo de detecção variou de 14,2 a 6,2%. Pedrosa et al 18 verificaram que crianças diagnosticadas com hanseníase tiveram pelo menos um contato intradomiciliar positivo, das quais parte destes eram os avós, todos multibacilares. O contato com avós infectados foi considerado a fonte mais provável de infecção nessas crianças.…”