 |
|
|
| |
Drug-resistant TB that kills HIV patients is spreading
|
| |
| |
South Africa, 27 other nations hit by highly drug-resistant strain, experts say
Sabin Russell, SF Chronicle Medical Writer
Monday, February 26, 2007
(02-26) 04:00 PST Los Angeles -- A meeting of international AIDS researchers opened here Sunday amid growing concerns about a deadly strain of tuberculosis that has been killing HIV-infected patients in South Africa and has been spotted in 27 other countries around the world.
Known as XDR-TB, or extensively drug-resistant tuberculosis, the bug first drew wide attention in August at the 16th International AIDS Conference in Toronto. Fifty-two of 53 HIV-positive patients who had this type of tuberculosis at South African hospitals had died of it.
Researchers reported on Sunday they have found an estimated 600 cases of XDR-TB in South Africa, most of them among patients already infected with HIV, the virus that causes AIDS -- and 85 percent of those patients have died.
"XDR-TB is a wake-up call," said Dr. Paul Nunn, coordinator for tuberculosis control programs at the World Health Organization in Geneva, during the 14th annual Conference on Retroviruses and Opportunistic Infections.
The meeting has drawn 3,800 of the world's leading AIDS researchers to report the latest scientific news on the spread of the epidemic, which has killed an estimated 25 million people worldwide since it first emerged 25 years ago.
Nunn said that XDR-TB has now been reported in 28 countries. The WHO estimates that each year, 27,000 people are infected with XDR-TB and about 16,000 of those people die.
Nunn said it is important to tell the world about XDR-TB "but without causing undue alarm."
He said the international community needs to spend $650 million a year on efforts to control various strains of multidrug resistant tuberculosis, of which XDR-TB is only the most recent and most deadly.
Ordinary tuberculosis remains a much larger threat on a global scale, responsible for 8.8 million cases, and 1.6 million deaths, every year.
The drug-resistant strain does not appear to spread easily, but it does represent a threat to both patients and health care workers who are HIV positive.
Karin Weyer, director of tuberculosis research at the South African Medical Research Council, told researchers at the Los Angeles meeting that roughly 30 percent of health care workers in her country are believed to be HIV positive.
Weyer said that six cases of suspected XDR-TB have been reported among South African health care workers. The disease was confirmed in four of them, who also had HIV. All four died.
Weyer said that XDR-TB has been found in 40 hospitals, and in every province in the country. Her team's estimate of 600 cases is based on studies showing it is turning up in about 10 percent of the 6,000 cases of multidrug-resistant TB found in the country last year.
There is mixed evidence as to the transmissibility of XDR-TB. In one study, 1,694 relatives and friends of patients with XDR-TB were tested. Among them, only 12 cases of multidrug-resistant tuberculosis were found, but there were no cases of XDR-TB.
A study of guinea pigs whose cages were placed in the ventilation stream from rooms housing XDR-TB patients was more of a concern. Eighty percent of the animals tested positive. "Most public health facilities in the developing world lack airborne infection control procedures," she said.
According to Nunn, XDR-TB is a form of tuberculosis that withstands not only first-line antibiotic therapies, but also at least two types of second-line antibiotics used to treat drug-resistant strains. Those second-line therapies include a class of antibiotics called fluoroquinolones as well as a variety of injectable treatments.
Those therapies are much more costly than conventional tuberculosis treatments, but drug-resistant strains crop up when the simpler therapies are not properly managed. Similarly, XDR-TB appears to be not so much a spreading strain as a type of mutant tuberculosis that now readily forms when second-line TB treatment is poorly managed as well.
The federal Centers for Disease Control and Prevention has tracked cases in the United States that meet the XDR-TB definition as far back at 1993. In March, it said that there had been 17 such cases from 2001-04. Since 1993, U.S. patients with XDR-TB were 64 percent more likely to die of the disease than patients with drug-resistant TB.
|
| |
|
|
|
|
|
