The tuberculosis case of the quarantined man at Grady Memorial Hospital illustrates the need to continue research and funding for new drugs, says Dr. Michael Leonard, assistant professor of infectious diseases at Emory University.

"My fear is that there's a sense of complacency in the public, that people don't feel like TB is an issue," he said. "It still is a big issue, it is a very communicable disease."

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Electron micrograph transmission of mycobacterium tuberculosis. The strain is resistant to almost all drugs used to treat TB.

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World health officials first began documenting the extensively drug-resistant tuberculosis strain — known as XDR-TB — in 2006, after analyzing 18,000 TB samples taken between 2000 and 2004 from around the world. Overall, the World Health Organization says, hundreds of cases have been found in every sector of the globe — by 2004 amounting to 11 percent of all drug-resistant cases recorded in industrialized countries.

U.S. health officials say TB cases that respond to drug treatment are at an all-time low and that drug-resistant strains are incredibly rare. In the United States, only 49 cases of XDR-TB have been reported between 1993 and 2006.

Grady — the Southeast's center for TB treatment — has a 26-bed respiratory infection isolation unit and treats about 100 TB patients a year, Leonard said. A multi-resistant or extreme strain like the kind infecting the Atlanta man is "virtually unheard of," he said.

The new strain is not considered more infectious than other types of tuberculosis, but it is far more difficult to treat because it resists at least two of the most potent anti-TB drugs, isoniazid and rifampin, and at least three of the six secondary drugs — among them, amikacin, capreomycin, or kanamycin, infectious disease experts say.

The largest known outbreak of XDR-TB occurred in the South African province of KwaZulu Natal in 2006, where 52 of 53 people diagnosed with the disease died. Of those 53 diagnosed, 44 had been tested for HIV and all were HIV-positive, according to the WHO, which says the bacterial strain is far more dangerous for people with compromised immune systems.

Several countries with good TB control programs have shown that a cure is possible for up to 30 percent of affected people with the strain. U.S. cases are so rare that good data are not available on the cure rate here, researchers said.

Treating the highly resistant strain requires a combination of treatment therapies.

The Atlanta man has said he plans to go to undergo treatment at the National Jewish Medical and Research Center in Denver, a leader in multi-drug-resistant tuberculosis research.

Dr. Charles Daley, who heads that department, said the Denver hospital provides specialized services for those with resistant strains of TB, which could include surgery to remove part of the infected lung.

Daley said there is no real rush to begin treatment, as "the pace of tuberculosis is very slow," and he stressed the importance of finding the right combination of drugs and surgery. Since the strain doesn't respond to many drugs, "we want to make sure we get all the facts before we begin any treatment," Daley said.