People with HIV/AIDS have immune systems weakened by the impact of the illness. As their T helper cells (CD4 cells) continually die off, the immune system has less chance of fighting off viruses and invasive bacteria, leaving HIV/AIDS patients susceptible to opportunistic infections. People with healthy immune systems can fight off these illnesses, but they can pose serious risks for those with HIV/AIDS. Many deaths from HIV/AIDS is the result of one of the several opportunistic infections.
Tuberculosis among people with AIDS is a larger problem in countries with fewer resources than in developed countries, but it is still the leading cause of death worldwide of AIDS and HIV-positive patients. The disease is caused by a bacteria and commonly affects the lungs, but can also negatively affect the kidneys, brain, spine, and other internal organs. TB is spread through the air when an infected person coughs, sneezes, speaks, or sings.