Active surveillance of leprosy contacts in country with low prevalence rate.

For advanced control of leprosy in Pakistan where the World Health Organization leprosy elimination goal was achieved in 1996, we conducted surveillance of Mycobacterium leprae-seropositive patients and their contacts and drug resistant strains of M. leprae. We measured anti-PGL-I antibody level in sera from leprosy patients and their contacts for early detection of M. leprae infection. Out of 34 leprosy patients undergoing treatment, 4 lepromatous leprosy patients were antibody positive, and 6.8 to 23.7 percent of occupational or household contacts were seropositive. Furthermore, three cases (1.2%) had a high antibody titer. For surveillance of drug resistant strains of M. leprae, dapsone and rifampin were targeted. Four out of 18 polymerase chain reaction (PCR) positive samples had mutation in folP gene, and among 10 PCR positive samples, one had a mutation in the rpoB gene. These results indicate that serological analysis of patient contacts might be useful to find out high risk individuals, and there are M. leprae strains resistant to chemotherapeutic agents in Pakistan.