People taking highly active antiretroviral therapy for HIV infection remain susceptible to tuberculosis

People taking highly active antiretroviral therapy (HAART) for HIV infection remain susceptible to tuberculosis, though the risk is lower than for HIV-infected patients not on HAART, according to an article in the Dec. 15 issue of Clinical Infectious Diseases, now available online.

Opportunistic infections such as tuberculosis (TB) can be fatal for immunocompromised patients. HAART not only reduces the viral load of HIV, but it also often helps to keep other infections such as TB under control. In fact, previous studies indicate that HAART can reduce the risk of TB in HIV patients by 70 to 90 percent. Although HIV-infected people living in industrialized nations are at lower risk of TB than those living in resource-poor countries, it continues to be a significant problem for HIV-infected people everywhere.

A group of European and American researchers followed patients with HIV for three years after they began HAART. The rate of tuberculosis was highest within the first three months of therapy, but declined after longer HAART exposure. Patients' risk of developing tuberculosis more than doubled if HAART did not successfully control their HIV. Patients were also more likely to develop TB if they were more immunodeficient when they started taking HAART.

HIV-infected patients from industrialized nations might develop TB if they were exposed to the tuberculosis organism in the past, especially for those emigrating from resource-poor countries. Their weakened immune status can allow reactivation of latent TB infection, according to lead author Enrico Girardi, MD, of the Istituto Nazionale per le Malattie Infettive Lazzaro Spallanzani in Rome.

But they don't necessarily have to leave the country to contract TB. HIV-infected American and European patients who are "exposed to someone with tuberculosis, for example in a hospital setting, are at increased risk of acquiring tuberculosis infection and of developing active tuberculosis within a short time, usually six months to one year," Dr. Girardi said.

Since TB is a potentially deadly opportunistic infection for patients with HIV, doctors need to be aware of the risk and take certain precautionary measures. "HIV-infected patients, even when treated with HAART, remain at increased risk of developing tuberculosis," Dr. Girardi said. "Thus, physicians caring for patients with HIV should continue to screen for and to treat latent tuberculosis infection in their patients, even if they have minor levels of immune suppression or are successfully treated with HAART." Health care settings should also maintain strict control measures to prevent the spread of tuberculosis to patients being treated for HIV, Dr. Girardi added.

In an accompanying editorial commentary, Stephen D. Lawn, MRCP, MD, and Robin Wood, MBChB, of the Desmond Tutu HIV Centre in South Africa indicated similar findings (unpublished) related to patients' immunological response to HAART and subsequent development of TB. The commentary concludes that HIV-infected patients' risk for infection with TB "remains elevated among those receiving treatment in both high- and low-income countries."