WASHINGTON - The federal government last week detained and quarantined an Atlanta man who had spent nearly two weeks traveling in the United States, Canada and Europe with "extensively drug-resistant" tuberculosis, a rare and often fatal form of the infection, officials said yesterday.

The Centers for Disease Control and Prevention imposed an "order of isolation" Friday after catching up with the man, who had flown into Montreal the day before and then driven to New York City. He was flown Monday in a government plane to Atlanta, where he is undergoing treatment.

Although states occasionally use their authority to forcibly detain and treat patients with infections, this was the first time since 1963 that the federal government had done so. The last case involved suspected importation of smallpox, a disease eradicated in the 1970s.

The CDC and the two airlines that transported the man twice across the Atlantic are laboriously trying to learn who had close, prolonged contact with him. Those people - potentially dozens on two continents - will then be contacted by local health departments.

"We don't think, from past scientific investigation, that their risk is high. But we want to offer them the chance to be tested," CDC Director Julie Gerberding said yesterday afternoon.

Although many details of the patient's recent activities were unknown or were not being disclosed, officials said he recently had been diagnosed and told not to travel when he left the United States on May 12.

After testing revealed his tuberculosis was "extensively drug-resistant," he was contacted in Europe by health authorities and told not to take a commercial flight home - advice he also ignored.

Martin Cetron, a physician who directs the CDC's Division of Global Migration and Quarantine, said he spoke to the man by phone Friday and directed him to a New York hospital. The man went willingly.

While the man had broken the "covenant of trust" that is usually sufficient to keep infectious TB patients from willfully exposing others, "from our perspective no laws were broken here," Gerberding said.

TB cases resistant to the two first-line classes of drugs and to at least two second-line classes have been detected in 37 countries and are increasing.

It is especially a problem in places such as South Africa and the former Soviet Union, where treatment is inadequate or the prevalence of HIV infection is high.

So-called XDR-TB is rare in this country, with only 49 cases detected since 1993, of which at least 12 were fatal, according to a CDC report in March.

Earlier this month, public-health officials in Arizona obtained a court order allowing them to confine and treat a 27-year-old dual Russian-U.S. citizen who had undergone months of TB treatment in Russia, where he had often been homeless. He is undergoing treatment for XDR-TB in a Phoenix hospital.

In most people, the body's immune system controls the TB bacterium on its own, forcing it to become "latent," or inactive. Drug resistance does not make that less likely, nor does it make the microbe inherently more virulent or contagious.

Instead, XDR-TB's danger is that when it does cause active illness, the infection is very hard to cure. That, in turn, increases the risk that it will be passed on to someone else, and that patients ill from it will die.

XDR-TB often occurs in prison populations and in people infected with HIV. Officials would not say yesterday whether the quarantined patient had either of those risk factors.

Officials at CDC and the Public Health Agency of Canada sketched this account:

The man was diagnosed with tuberculosis when he had an abnormal chest X-ray, which was done for some other reason. A laboratory culture revealed TB bacteria in his phlegm. But he had no symptoms, and in particular no fever or cough.

He flew from Atlanta to Paris on May 12 on Air France Flight 385, arriving the next day. He flew back from Europe on Thursday aboard Czech Airlines Flight 0104, which departed from Prague. That flight arrived the same day at Montreal International Airport. He left Montreal in a rented car and drove to the United States, entering at Champlain, N.Y.

His wife was with him in New York and accompanied him in the CDC plane to Atlanta. Where she met him - or whether she traveled to Europe with him - was unclear yesterday.

Officials did not say how many countries he had visited.

Video and details about drug- resistant TB are posted at http://go.philly.com/health