Antibiotic-Resistant TB a New Peril, U.N. Says
Eruptions of antibiotic-resistant tuberculosis in “hot zones” on at least four continents portend the global spread of virulent new strains of the disease, according to a study released Wednesday by the World Health Organization.
“This report provides the first scientific evidence for what we most feared but could not previously prove: The world again faces the specter of incurable tuberculosis,” Dr. Michael Iseman, a University of Colorado TB researcher who participated in the study, told a Washington news conference.
Avoiding such an epidemic, WHO officials added, will require more aggressive treatment of tuberculosis in its earliest stages and in the developing world, where it is most common.
In a cruel irony, the deadly new strains have emerged as a result of improperly administered TB drug therapies that long have been successful in battling the disease around the world. “This is a creation of man, not nature,” Iseman said.
Researchers have previously known that when the standard TB antibiotics are not given in their full and proper doses, the TB bacteria not only survive but mutate into forms resistant to one or more of the drugs. The resistant disease then can be spread to other people.
Tuberculosis is an extremely infectious disease that kills an estimated 3 million people annually. About one-third of the world’s population is thought to be infected, although not all carriers develop symptoms, which include fever, a bloody cough and ravaged lungs. About 14% of current cases are believed to be resistant to at least one antibiotic, but researchers are most concerned about those strains--about 2% of new diagnoses--able to withstand the two most widely used antibiotics.
This multi-drug-resistant form of TB is extremely expensive to treat--costs run as high as $270,000 per patient--and very difficult to cure. In developing countries, the cost and lack of medicine required to treat multi-drug-resistant TB mean that it is virtually incurable, WHO officials said.
The study released Wednesday, the most extensive to date on antibiotic-resistant tuberculosis, was conducted by WHO, the U.S. Centers for Disease Control and Prevention in Atlanta and the Paris-based International Union Against Tuberculosis, and was partly funded by the U.S. Agency for International Development, or AID. Researchers affiliated with 22 international laboratories surveyed 50,000 cases in 35 countries.
The report identified “hot zones” of multi-drug-resistant TB in India, Russia, Latvia, Estonia, Argentina, the Dominican Republic and the Ivory Coast. Iseman, however, suggested that as a practical matter, “it is on every continent and probably in every country.”
Although multi-drug-resistant cases account for only about 2% of new diagnoses each year, health officials--noting that global trade and travel facilitate the spread of disease worldwide--are eager to control such cases before they multiply.
“TB is back, and it is going to be one of the most deadly diseases we will face in the next millennium and especially the next generation,” said Sally Shelton Colby, assistant administrator of AID.
But officials said Wednesday that drug-resistant TB can be effectively fought with prevention programs, and they cited the example of the United States, where drug-resistant cases of TB have dropped since 1990. The United States counted 237 cases of multi-drug-resistant TB in 1993--or 1.6% of all TB cases that year, down from 3.5% in 1991--according to the CDC.
In Los Angeles County, the incidence of multi-drug-resistant TB has also declined. The Department of Health Services found that 12 of the 1,064 TB cases tested in 1996--or about 1%--were resistant to more than one drug, down from 3.3% of cases tested in 1994. “If anything, there’s a declining problem in L.A. County [because] we’ve had good treatment programs here,” said Dr. Paul T. Davidson, director of the department’s TB control unit.
Standard treatment of tuberculosis was developed following World War II and requires patients to take a sequence of drugs for six to eight months, ideally under the supervision of a doctor or nurse. When fully administered, this results in cure rates of 85% to 95%, according to WHO.
The new antibiotic-resistant TB bacteria develop by mutation when patients discontinue treatment early either because they begin to feel better or because they cannot afford to continue taking the drugs. Sometimes poorly trained health care administrators also stop treatments too soon.
The answer, WHO officials said, is a program called DOTS, for Directly Observed Treatment, Short-course. Under it, trained observers personally supervise the administration of tuberculosis drugs as often as three times a week through the full treatment period, ensuring its completion. A DOTS program in New York City is credited with curtailing a surge in drug-resistant TB bacteria there and accounting for most of the decline in the U.S.
But expanding DOTS into the TB “hot zones,” especially those in the developing world, will require more money for drugs and health care training, WHO officials said.
Dr. Richard Baumgarner, deputy director of the WHO tuberculosis program, said the organization currently spends $11 million a year on eradication programs and that $100 million is needed.
“That [amount of money] would probably turn the tide, but we haven’t been able to find it,” Baumgarner said.
Staff writer Terence Monmaney in Los Angeles contributed to this report.
