RECURRENCE OF HIV-RELATED TUBERCULOSIS IN AN ENDEMIC AREA MAY BE DUE TO RELAPSE OR REINFECTION

Setting: Two Research Clinics within Nairobi, Kenya, one in the Infectious Diseases Hospital, the national referral centre for tuberculosis, and one in a community based project in Pumwani district, and the Bacterial Molecular Genetics Unit at the London School of Hygiene and Tropical Medicine. Objective: To determine whether recurrence of tuberculosis after 'adequate' treatment was due to reinfection with a different isolate of Mycobacterium tuberculosis or to relapse of the original infection. Design: A retrospective comparison by DNA fingerprinting of sets of isolates of M. tuberculosis from patients with recurrence of tuberculosis and in whom isolates from the original episode had been stored was made. Five patients with recurrence of tuberculosis two to nineteen months after adequate treatment and documented clearance of disease were studied. Results: In one patient, fingerprints of the isolates of M. tuberculosis from the recurrence were quite different to those from the original episode; in the other four, the fingerprints were identical. Conclusion: Reinfection rather than relapse was the cause of recurrence in at least one patient. The high 'relapse' rates seen in HIV-related tuberculosis in Africa may in part be due to increased susceptibility to reinfection and not to treatment failure.