CDC concerned about drug-resistant tuberculosis that is linked to immigrants

Erin Allday:

A new strain of drug-resistant tuberculosis that is "virtually untreatable" is raising alarm among public health officials, even as the less virulent, and much more common, form of TB continues to decline in the United States.

The Centers for Disease Control and Prevention reported for the first time Thursday on the emergence of "extensively drug-resistant" tuberculosis, which does not respond to most first- or second-line drug therapies for TB.

The new strain is still rare in the United States. But public health officials in San Francisco, where the tuberculosis rate is the highest in the country, say they're seeing patients who face an increasingly resilient form of TB and don't respond to any of the drugs used to fight the disease.

"We're seeing much more extreme forms of resistance than ever before. It used to be just two of the front-line drugs, and now it's all of them," said Dr. L. Masae Kawamura, director of San Francisco's TB Control Section and chairwoman of the federal Advisory Council for the Elimination of Tuberculosis. "It often results in having to have operations where you remove the source of infection, you remove part of the lung. It's really turned back the time to pre-antibiotic era."

Tuberculosis, a bacterium that usually affects the lungs, is highly treatable in most cases, with a mortality rate of about 5 percent in the United States. Using a treatment course of four drugs, it generally takes about six months, and $3,000, to cure.

But it's critical that patients adhere to a strict drug-maintenance schedule, or they risk developing a resistance to the drugs. Patients who are identified as drug-resistant do not respond to two of the four first-line drugs. Those who suffer the extensively drug-resistant, or XDR, form do not respond to three of the six second-line drugs.

Patients with drug-resistant TB, including XDR, can take up to two years to be cured -- for a cost of up to $250,000, according to Dr. Robert Benjamin, medical director for the Alameda County TB control program. They remain contagious for a longer period, and worldwide 25 percent to 33 percent of them die.

Dr. Marcos Espinal, executive secretary of the World Health Organization's Stop TB Partnership, said Thursday that new research is needed to develop new drugs in order to treat the tougher strains. "If people are failing first- and second-line drugs, and we don't have a new drug in the pipeline for immediate use, that's a major crisis we're facing," he said.

Drug-resistant tuberculosis cases increased 13.3 percent in the United States from 2003 to 2004 -- the largest year-over-year increase since 1993. Such cases now account for 1.2 percent of total TB cases in the United States.

San Francisco gets one to four drug-resistant cases a year, Kawamura said. Almost all of the cases have been in immigrants from countries where TB is more prevalent and treatments are less rigorous.

Many public health offices in the United States, including San Francisco, have developed a strict program to monitor patients with TB, checking in with them daily to make sure they take the medication. But in other parts of the world, treatment isn't nearly as thorough. Patients are more likely to get treatment from private health-care providers who don't get government training in dealing with TB, or they use over-the-counter drugs to self-medicate.

"Drug resistance is largely a man-made problem. Poor treatment practices are by and large what lead to drug resistance," said Dr. Philip Hopewell, a UCSF professor of medicine who helped write the World Health Organization's first international standards for TB care, released this week. "If a patient arrives here (in the United States) with tuberculosis, they get treated effectively. We don't create the problem here. By and large, the drug-resistant cases we get are imported."

In fact, of the 128 cases of drug-resistant TB reported in the United States in 2004, 97 were in foreign-born patients, the CDC said.

It's critical, public health officials said Thursday, that the United States take an active role in improving both detection and treatment of tuberculosis overseas.

"Immigration is what has made America great, but with global mobility also comes mobility of diseases," Benjamin said. "If we fail to provide the technical assistance necessary to improve TB control in those countries, we will certainly bear the brunt of an incredibly dangerous and costly disease."

About a third of people worldwide are infected with tuberculosis, according to the CDC. About 9 million active cases show up, and 2 million people die of TB every year. With the spread of HIV, which weakens the immune system and leaves patients more susceptible to tuberculosis, TB is reaching pandemic levels in parts of Africa, the CDC said.

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