Tuberculosis + HIV = A Complex Calculus

Tuberculosis (TB) continues to be a serious public health threat for people living with HIV/AIDS (PLWHA), especially for those with severely compromised immune systems. Unfortunately, the people disproportionately at risk for TB are the very people most at risk for HIV: people who are poor, underserved, uninsured, or minority—those whom Ryan White HIV/AIDS Program providers treat. To improve health outcomes and deliver comprehensive care, providers must—in addition to everything else they do—serve as TB diagnosticians.

Although TB incidence has decreased over the years, its decline has leveled off. From 1993 to 2000, the average annual percentage decline was 7.3 percent; between 2000 and 2007, it dropped to 3.8 percent annually.1 If rates of decline remain sluggish, goals to eliminate TB will not be met for a century. Moreover, increases in multidrug resistant (MDR-TB) and extensively drug-resistant TB (XDR-TB) have been reported to the Health Resources and Services Administration and the Centers for Disease Control and Prevention (CDC).

Tuberculosis Transmission and Symptoms

TB is an airborne pulmonary disease. TB bacteria spread into the air when a person with untreated TB coughs, sneezes, spits, sings, laughs, shouts, or even speaks; people become infected by inhaling those bacteria. HIV infection significantly increases the risk of contracting TB, as do frequency and duration of exposure and density of infectious droplets in the air. In areas with poor ventilation, TB bacteria can remain in the air for several hours, but sunlight and ultraviolet light can kill them.

Common symptoms of pulmonary TB include sudden weight loss, shortness of breath, cough, night sweats, fatigue, and fever. Pulmonary TB can be easily mistaken for bacterial pneumonia.5,6

Latent and Active TB Infection

Latent TB infection (LTBI) occurs when a person is infected with tuberculosis but does not have active TB disease (i.e., they are not infectious in this stage). Infants, young children, injection drug users, diabetics, people with a recent TB infection, older adults, immunocompromised persons, and people inappropriately treated for TB are more likely to develop active TB disease. HIV dramatically increases the risk for reactivation of LTBI, from 10 percent over a lifetime to 10 percent per year.

In active TB (called primary disease), tubercle bacilli overpower the immune system, which attempts to seal off and kill infected cells by forming masses of inflamed tissue that surround infected cells (i.e., granulomas). TB bacilli start to multiply in the lungs and, sometimes, other parts of the body, leaving scarring and cavities filled with dead cells and infectious bacteria.

Although TB is an AIDS-defining opportunistic infection, it can occur at any CD4 cell count. TB progresses more rapidly in PLWHA, and HIV disease progression is accelerated by TB coinfection.7,8,9