Impact of PGL-I Seropositivity on the Protective Effect of BCG Vaccination among Leprosy Contacts: A Cohort Study

Although leprosy has become a neglected disease, it is an important cause of disability, and 250,000 new cases are still diagnosed worldwide every year. The current study was carried out in Brazil, where almost 40,000 new cases of leprosy are diagnosed every year. The study targeted contacts of leprosy patients, who are at the highest risk of contracting the disease. We studied 2,135 contacts who were diagnosed at the Leprosy Outpatient Clinic at the Oswaldo Cruz Foundation in Rio de Janeiro, RJ, Brazil, between 1987 and 2007. The presence of antibodies against a specific Mycobacterium leprae antigen (PGL-I) at the first examination and BCG vaccination status were evaluated. PGL-I-positive contacts had a higher risk of developing leprosy than PGL-I-negative contacts. Among the former, vaccinated contacts were at higher risk than unvaccinated contacts. Our results indicate that contact examination combined with PGL-I testing and BCG vaccination appears to justify the targeting of PGL-I-positive individuals for enhanced surveillance. Furthermore, it is highly recommended that PGL-I-positive contacts and contacts with a high familial bacterial index (i.e., the sum of results from index and co-prevalent cases), regardless of serological response, should be monitored. This group could be considered as a target for chemoprophylaxis

Positividade sorológica antiPGL-I em contatos domiciliares e peridomiciliares de hanseníase em área urbana Seropositivity with anti-PGL-I of household and neighbours contacts of leprosy patients in an urban area

FUNDAMENTOS: Pesquisas atuais buscam avaliar a prevalência de pessoas infectadas pelo M. leprae, bem como o valor preditivo dos testes utilizados, em meio aos quais está a sorologia, que detecta anticorpos contra um antígeno específico da parede do Mycobacterium leprae, o glicolipídio fenólico (PGL-I). OBJETIVOS: Conhecer a taxa de infecção em contatos intra e peridomiciliares, e a relação de soropositividade com sexo, idade e grupo multibacilar/paucibacilar. MATERIAIS E MÉTODOS: Inquérito soroepidemiológico em contatos domiciliares e peridomiciliares dos casos notificados como hanseníase entre 1998 e 2002, no segundo distrito do Município de Duque de Caxias, RJ, utilizando o teste sorológico rápido de fluxo lateral ou ML Flow. RESULTADOS: Em 390 domicílios de casos de hanseníase foram identificados 2.130 contatos, e submetidos à sorologia 1.866 (12,4% de perda). A soropositividade foi de 15,7% (292/1.866), sendo 15,8% no domicílio e 15,6% no peridomicílio. Também não houve diferença na relação entre soropositividade e sexo e em maiores e menores de 15 anos. Observou-se diferença significativa na soropositividade de contatos de casos de hanseníase MB (67,5%), duas vezes maior do que a dos casos de PB (32,5%). DISCUSSÃO / CONCLUSÃO: Nas condições de moradia da periferia urbana de área endêmica devem ser submetidos igualmente à vigilância epidemiológica os contatos domiciliares e peridomiciliares.<br>BACKGROUND: Actually many studies have been made to evaluate the predictive value of tests that identify patients infected by Mycobacterium leprae. Among then, the serology that determinates the presence o M. leprae specific antibody. OBJECTIVES: To know the infections tax among households and direct neighbours contacts, establish soropositivity relationship according to sex, household/ neighbour, age and classification of leprosy of the index case (paucibacillary x multibacillary). PATIENTS AND METHODS: seroepidemiological study covering all the household and neighbours of leprosy patients diagnosticated from 1998 to 2002, in the second district of Duque de Caxias, Rio de Janeiro, using fast ML-Flow. RESULTS: A total of 2.130 contacts were identified in 390 domiciles of leprosy patients. Of the 2130 contacts, 1866 were submmited to serology (12.4% lost). Seroprevalence was 15,7%(292/1866); 15.8% household and 15.6% neighbour. The relationship of seropositivity with sex and age (>15 >15 years old) did not shown any statistic difference. But it was seen among contacts of MB index cases ( 67,5%) 2 times higher than contacts of PB cases (32,5%). DISCUSSION / CONCLUSION: In highly endemic areas for leprosy, situated at peripheral metropoliten cities not only household contacts of the index case, but also people living in the close vicinity were more likely to harbour antibodies against M. leprae. Through measuring the serological status of contacts and using a broader definition for them, higher risk groups can be more specifically identified