ILEP organisations should strive for high BCG coverage in communities at risk of leprosy

The central thesis of this paper is that the EPI policy of a BCG vaccination at birth or in the first year of life provides proven partial protection against leprosy and that ILEP organisations should actively encourage government health services to maintain a high coverage. A literature review identified 12 case-control studies showing a median vaccine efficacy of 63% (range 20-90%). Two prospective studies and two randomised community trials showed a median efficacy of 70% (range 42-80%). The duration of this partial protection is at least 10-15 years. Studies of the long-term protective effect of BCG vaccination against leprosy have not been conducted. One trial has demonstrated a reduction of tuberculosis incidence up to 40 years after vaccination with BCG. There is a growing consensus that BCG works by ‘upgrading’ the immune response to M. leprae, moving leprosy cases from the lepromatous end of the Ridley-Jopling classification to the tuberculoid end or even makes it possible for infection to remain subclinical. An analysis of national BCG coverage figures as reported to WHO showed that the global mean coverage increased from 58% in 1980 to 88% in 2003. The absolute number of countries reporting less than 80% coverage has decreased from 78 out of 105 in 1981 to 32 of 157 in 2003. Only four countries reported coverages below 60% in 2003. Twenty of the 53 African countries reported coverages below 80% in 2003 against five of 38 countries in Asia, five of 13 countries in Oceania and two of 27 in Central and South America. Comparison of officially reported national coverage to estimates of coverage from special surveys clearly shows that the national figure may not adequately reflect the local situation. Rural communities often have lower coverage than urban populations. Slum households have lower coverage than non-slum households. Remote areas may not be touched by modem health services. Pockets of low BCG coverage exist in countries where leprosy is endemic and ILEP organisations are active. ILEP organisations can make an impact, not by getting involved in vaccination work directly, but by monitoring the BCG coverage and advocating for adequate provision of MCH services in the communities in which they work. This will reduce the risk of leprosy in children up to 15 years of age, provide a number of other benefits to the mothers and children involved and potentially contribute to a reduction of leprosy incidence on the longer term. If the partial protection imparted by BCG is life-long, adding a consistently high BCG coverage to the usual strategy of early case detection and treatment could result in a halving of the leprosy incidence in 2020.