BCG revaccination does not protect against leprosy in the Brazilian Amazon: a cluster randomised trial.

BACKGROUND: Although BCG has been found to impart protection against leprosy in many populations, the utility of repeat or booster BCG vaccinations is still unclear. When a policy of giving a second BCG dose to school children in Brazil was introduced, a trial was conducted to assess its impact against tuberculosis, and a leprosy component was then undertaken in parallel. OBJECTIVE: to estimate the protection against leprosy imparted by a second dose of BCG given to schoolchildren. METHODS AND FINDINGS: This is a cluster randomised community trial, with 6 years and 8 months of follow-up. STUDY SITE: City of Manaus, Amazon region, a leprosy-endemic area in Brazil. PARTICIPANTS: 99,770 school children with neonatal BCG (aged 7-14 years at baseline), of whom 42,662 were in the intervention arm (revaccination). INTERVENTION: BCG given by intradermal injection. MAIN OUTCOME: Leprosy (all clinical forms). RESULTS: The incidence rate ratio of leprosy in the intervention over the control arm within the follow-up, in schoolchildren with neonatal BCG, controlled for potential confounders and adjusted for clustering, was 0.99 (95% confidence interval: 0.68 to 1.45). CONCLUSIONS/SIGNIFICANCE: There was no evidence of protection conferred by the second dose of BCG vaccination in school children against leprosy during the trial follow-up. These results point to a need to consider the effectiveness of the current policy of BCG vaccination of contacts of leprosy cases in Brazilian Amazon region.

Design of the leprosy component of the Brazilian BCG revaccination trial for assessing BCG effectiveness against leprosy in school children.

BACKGROUND: BCG vaccination confers protection against leprosy, and vaccination among household contacts has been recommended in Brazil. Nevertheless, vaccination of the entire community against leprosy is not advocated as leprosy has low incidence in most populations. Despite that, in Brazil, BCG vaccination is recommended among school children to prevent tuberculosis and this large scale vaccination may also affect the occurrence of leprosy, which led to investigations of its impact on leprosy in endemic areas of Brazil. OBJECTIVES: To estimate the effectiveness against leprosy of a dose of BCG vaccine given to school children in a population with a high coverage of neonatal BCG. Long term objectives are to compare the impact of vaccination among schoolchildren with the existing recommendation to vaccinate household contacts of leprosy. STUDY DESIGN: Cluster randomized controlled field trial with no placebo. STUDY POPULATION: Children aged 7 to 14 years attending state schools with high coverage of neonatal BCG. METHODS: 286 state schools in the city of Manaus, Brazil, were randomized to receive BCG or not. Identifying information was collected for 152,438 school children, of whom 72,980 are in intervention schools. BCG vaccination was given intradermically to children in schools allocated to vaccination. Follow-up relies on ascertainement of cases diagnosed at the health services and notified to the reference center for leprosy.

Upward trend in the rate of detection of new cases of leprosy in the State of Bahia, Brazil

BACKGROUND: The worldwide fall in the rate of detection of new cases of leprosy has been partly attributed to the introduction of multidrug therapy and other improvements in control programs. However, the rate of detection of new cases has not decreased in Brazil. METHODS: An analysis was made of the temporal distribution of 18,872 newly reported leprosy cases in Bahia, Brazil, from 1974 to 1997. Population denominators for the annual detection rate were obtained from population estimates based on the national census. Trends were presented by sex, date of birth, date of diagnosis, date of release, clinical form and by residence in areas which had notified cases in the 5 years prior to the rise in detection rate. RESULTS: There was a marked increase in the new case detection rate (NCDR) in the State of Bahia, from 0.19 to 1.43 cases per 10,000 inhabitants during the study period, an increment of nearly 7% to 8% per year. This increase was also observed in people aged 14 years and younger. During this period tuberculoid and indeterminate forms have become predominant among women and younger people. The average age of male cases has shifted toward younger ages. CONCLUSIONS: We interpret this pattern to mean that the increase in NCDR reflects a real increase in incidence of leprosy, whether or not accompanied by improved detection.