Study on BCG protection against leprosy in Sri Lanka

BCG (Bacillus Calmette and Guerin) vaccine is known to have a protective effect against leprosy. But the degree of protection varies according to the geographical area. The aim of the study was to detect whether there is significant protection from BCG against leprosy in Sri Lanka. BCG vaccine is used as a preventive measure in countries where it has been proven to have a protective effect.

The study was carried out at Teaching Hospital Colombo South. One hundred seventy-six (176) index patients with leprosy and one hundred sixty nine (169) household contacts without the disease were studied. Presence of BCG scar and reaction to Mantoux test were compared between two groups. 79.8% contacts without the disease had skin induration 5-10 mm following Mantoux test while only 3.4% patients showed such a response. BCG scar was found in 95.8% contacts and 52.8% patients. Odds ratio for Mantoux response was 0.008 (p< 0.001). It was 0.04 (p< 0.001) for the BCG scar.

In our study "positive" Mantoux reaction and presence of BCG scar were detected in a higher percentage of contacts without the disease compared to leprosy patients. BCG vaccine would have protected the contacts from developing the disease by enhancing immunity.