By Maggie Fox, Health and Science Editor

WASHINGTON, May 31 (Reuters) - A U.S. man infected with a dangerous form of tuberculosis who sparked an international incident when he fled health authorities arrived at a specialist hospital in Denver for treatment on Thursday.

National Jewish Medical and Research Center said the patient was feeling well when he arrived in the morning. He will undergo a series of tests, including a sputum test and chest X-rays that include a computed tomography or CT scan.

A spokesman for the U.S. Centers for Disease Control and Prevention said the patient's health maintenance organization, the non-profit Kaiser Permanente Foundation, paid for his transportation from a hospital in Atlanta to Denver.

A CDC nurse was aboard and the patient and all staff in contact with him wore tight-fitting respirator face masks that can filter out virus-carrying particles.

The patient's treatment will take months, possibly as long as 18 months, and will include a cocktail of antibiotics, the hospital said in a statement.

The CDC has said the patient, who was isolated after he arrived in the United States from Canada, is not likely to have been highly infectious, but they had to act because of his behavior. It was the first federal isolation order issued since a smallpox patient was detained in 1963.

The man has a difficult-to-treat form of tuberculosis called extensive drug resistant TB, or XDR TB. This strain resists both first- and second-line TB drugs and must be treated with a lengthy course of strong antibiotics.

The CDC, World Health Organization and European authorities are trying to trace people who sat close to the patient on two trans-Atlantic flights he took on May 13 and May 24, as well as air crew on the flights. The total is about 100 people.

While they say the risk of infection is low, it is possible someone may have been exposed. TB is more likely to infect people with immune conditions, including cancer patients and those infected with the AIDS virus.

"To date, no case of active TB has been identified as a result of exposure on a commercial aircraft," the WHO said in a statement in its Web site at http://who.int.

"Furthermore, no evidence of TB disease has been reported among those known to have been infected with M. tuberculosis during air travel."

The CDC traced more than 2,600 people who flew on aircraft with seven highly infectious TB patients from 1992 to 1994. "In only two of the investigations was there evidence to suggest transmission of M. tuberculosis infection: one from a cabin crew member to other crew members, and another from a passenger to other passengers," WHO said.

Transmission of TB usually requires close and sustained contact, and the CDC has said the U.S. XDR TB patient does not appear to be highly infectious and did not infect his fiancee, now his wife.

The patient, who spoke anonymously to the Atlanta Journal-Constitution newspaper, said he proceeded with a honeymoon in Europe despite having been advised by Georgia state health authorities not to fly, and then fled across Europe and then flew to Canada and drove into the United States, when he learned CDC officials were trying to stop him.

The CDC said it has learned from the incident, and only acted because of the man's behavior and the possible danger he posed to others. While XDR TB is curable, it costs an estimated $500,000 per patient.

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