By David Brown
Washington Post Staff Writer
Wednesday, March 25, 2009
The number of people worldwide infected with both HIV and tuberculosis is twice what experts had thought, although the incidence of TB worldwide is slowly falling.
That was the bad news -- and the good -- in the World Health Organization's annual report on tuberculosis released yesterday.
Simultaneous infection with the AIDS virus and the tuberculosis bacterium is potentially both a personal and public health catastrophe. HIV greatly accelerates the progress of TB, and greater prevalence of TB -- and especially of inadequately treated cases that promote drug-resistant strains of the germ -- is a threat to everyone.
There were 9.27 million new cases of TB in 2007, with about half occurring in five countries: India, China, Indonesia, Nigeria and South Africa. Only about two-thirds of the cases were diagnosed. About 5.3 million new cases -- or 57 percent of the total -- were being treated, which generally requires that a person take a combination of drugs for six months.
The incidence of tuberculosis in 2007 was 139 new infections per 100,000 people, a decline from 142 in 2004. Because of the growth in the world's population, the number of new cases in 2007 was slightly higher than in the few years prior.
About 1.3 million tuberculosis patients who were not infected with HIV, and about 456,000 who were, died of the disease in 2007. TB is the leading cause of death in AIDS patients and accounted for about one-quarter of the 2 million AIDS deaths worldwide.
The recent push to bring HIV testing and treatment to sub-Saharan Africa, combined with improvements in disease surveillance overall, is revealing for the first time the extent of "co-infection." The number of countries reporting the proportion of their TB patients who are also HIV-positive has risen from 15 to 64 in the last three years.
In 2006, WHO epidemiologists estimated that 700,000 people with the AIDS virus developed active tuberculosis. For 2007, the estimate jumped to about 1.4 million -- an increase that reflected better case-finding and reporting, not an actual doubling of infections.
"Many programs have been insisting in countries, especially in Africa, that every single case of HIV should be tested for TB," said Mario Raviglione, head of the Stop TB department at WHO.
Treatment of both infections is usually required to restore someone to health.
Once someone whose immune system has been damaged by HIV becomes ill with tuberculosis, "without treatment, the likelihood of death is essentially 100 percent within six months," said Richard Chaisson, director of the Johns Hopkins Center for Tuberculosis Research. "The problem in Africa is HIV patients are not being diagnosed early enough. They die and they die quickly."
TB patients can be checked for HIV with a blood or saliva test, but it is more difficult to test HIV patients for TB. That requires them to cough up a sample of phlegm, which is then either examined under a microscope or cultured for the TB bacterium. Someone with symptoms suspicious for TB -- which principally but not exclusively infects the lungs -- also needs to get a chest X-ray.
Diagnosing both infections is important because it also allows medical practitioners to protect others from the disease. An outbreak of drug-resistant TB that killed more than 50 people in South Africa several years ago turned out to have spread mostly in a hospital and its clinic.
About 500,000 of the 9.27 million new TB cases were resistant to two or more of the standard drugs used to treat TB. Being infected with a "multi-drug resistant" strain makes treatment longer and more expensive, and a cure less likely.
WHO estimates that $3.2 billion is needed for TB diagnosis and treatment this year, and $1.6 billion is available. About 80 percent of the money for TB control around the world comes from domestic governments and the rest from foreign aid, the World Bank, and the Global Fund to Fight AIDS, Tuberculosis and Malaria.
"The total figure [for TB control] keeps increasing, and at the same time, the gap keeps increasing, too," Raviglione said.