is one of the leading causes of death in people with HIV, resulting in an
estimated13 percent of AIDS deaths worldwide.
As Véronique LaCapra reports, doctors working with the World Health
Organization stress the need to coordinate the response to these two
catastrophic epidemics, and to integrate TB screening and treatment into HIV
than 2 billion people – one third of the world's population – are infected with
tuberculosis bacilli, the bacteria that cause TB. The
disease disproportionately affects the world's poor: the vast majority of TB
deaths are in developing countries.
the general population, 1 in 10 people who are infected with TB will develop
the disease in their lifetime. But for people who are HIV-positive, TB
presents a much greater risk.
Doctor Diane Havlir
is the Chief of the HIV/AIDS Division at San Francisco General Hospital in
California. She is active in the World Health Organization's efforts to combat
HIV and TB, and has been studying the relationship between these global
epidemics. "It's estimated that just over a third of all the people living
with HIV – which means over 10 million people – are infected with
tuberculosis." She says that in patients who have HIV disease, TB is the
leading cause of death.
suffering the highest incidence of HIV and AIDS bear much of the burden:
according to WHO, 85 percent of HIV-positive TB cases are in Africa.
can be difficult to diagnose, says Havlir, especially in developing countries,
which often have limited diagnostic tools. She says that in most places in the
world, tuberculosis is still diagnosed using a practice that was developed over
a hundred years ago: microscopic examination of sputum.
using a microscope to look for TB bacteria in the thick mucus people cough up
from their lungs often doesn't work. According to Havlir, only about 50 percent
of people infected with both TB and HIV will have enough tuberculosis bacilli
in their sputum to be visible under a microscope. "That really makes the
also challenging to recognize the symptoms of tuberculosis in someone
with HIV. An otherwise healthy person who gets sick from TB usually develops
pneumonia-like symptoms – coughing, fever, chest pains, and sweats.
in people with weak immune systems, like AIDS patients, TB can spread
throughout the body, entering lymph nodes, causing glands to swell, and
producing severe abdominal pain. Tuberculosis can also spread to the brain,
resulting in headaches and seizures.
proposes that to effectively fight the spread of tuberculosis, HIV programs
must make TB control a priority.
says the first step is to increase routine testing for TB in HIV clinics. Since
tuberculosis is highly contagious – spreading through the air when someone with
TB coughs, sneezes or even talks – early diagnosis is critical to preventing an
infected person from spreading the disease to others. "The sooner that we
find people, the sooner we can treat people, and the less […] time that they
are able to transmit tuberculosis to others," Havlir explains. Family
members are especially at risk, as are other patients in a health care
facility. Havlir says that just having people with TB wear a simple paper mask
over their mouths can help prevent transmission.
for TB can also provide direct benefits to the person getting tested, even if
the results are negative. For an HIV-positive person who does not have TB, says
Havlir, taking a single antibiotic – called isoniazid – may reduce their risk
of getting TB in the future by up to 60 percent.
tool that we have in order to prevent the risk for tuberculosis in our
HIV-infected patients is HIV therapy itself," says Havlir. One of the
reasons that people with HIV are so susceptible to TB is that the HIV virus
impairs their immune system. Taking anti-retroviral medications strengthens the
immune system, decreasing susceptibility to infection.
discusses these and other strategies to coordinate TB and HIV control in the
July 23rd issue of the Journal of the
American Medical Association.