Tuberculosis reinfection rates are higher in HIV-infected patients
NEW YORK (Reuters Health) Mar 09 - Tuberculosis (TB) reinfection rates are increased in patients with HIV, according to research from South Africa published online February 1st in The Journal of Infectious Diseases.
HIV infection increases the incidence of new and recurrent TB, the authors explain, but the rate of recurrent TB due to reinfection in patients with and without HIV infection is not known.
Dr. Judith R. Glynn from London School of Hygiene and Tropical Medicine and colleagues analyzed TB recurrence in South African gold miners with (n=342) and without (n=321) HIV. The miners had participated in an earlier study of new pulmonary tuberculosis.
TB recurred in 115 (34%) HIV-positive miners and 67 (21%) HIV-negative miners. Calculated as cases per 100 person-years at risk, the rate was significantly higher with HIV infection (19.7 cases) than without it (7.7 cases).
The effect of HIV infection on recurrence rates was much larger in patients with only 1 prior TB episode (hazard ratio, 2.8), the researchers note. The only other factor associated with recurrence was isoniazid resistance in the index episode.
In HIV-positive men, time since the first TB episode also contributed to the recurrence rate, with higher rates after the first 2 years, particularly in those with only a single previous TB episode.
On the other hand, total time since HIV seroconversion and duration of HIV infection before the index TB episode had little impact on TB recurrence rate.
After minimizing the probable contribution of relapse, the investigators say, recurrence was still roughly 3 times more frequent than incident TB in both HIV-negative and HIV-positive individuals.
"Tuberculosis recurrence rates, likely due to reinfection, were much higher than incidence rates," the authors conclude. "The findings suggest heterogeneity in susceptibility, implying that a vaccine could still provide useful protection in the population and strengthening the case for secondary preventive therapy."
In an editorial, Dr. Richard E. Chaisson from Johns Hopkins University, Baltimore, Maryland and Dr. Gavin J. Churchyard from Aurum Institute for Health Research, Johannesburg, South Africa agree with the researchers' conclusion. "The potential for an effective primary vaccine to control initial and thus recurrent tuberculosis, especially among HIV-infected persons, is enormous," they write. "After all, the best way to ensure that patients avoid a second episode of tuberculosis is to make certain that the first episode never occurs."
J Infect Dis 2010.
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