WASHINGTON - The government is investigating how a globe-trotting tuberculosis patient drove into the country after his name was put on a watch list - and given to U.S. border guards.

The episode showed a major gap in the nation's system to keep the direst of diseases from crossing borders. That the Atlanta man and his wife were cleared by border agents who had been told to stop them is one in a series of missed opportunities to catch a patient seemingly determined to elude health officials.

Worried infection specialists say it shows how vulnerable the nation is, because of outdated quarantine laws and the speed of international travel, to killer germs carried by tourists. What if, they ask, the now-quarantined man had carried not hard-to-spread tuberculosis but something very contagious like the next super-flu?

"It's regretful that we weren't able to stop that," Dr. Martin Cetron of the Centers for Disease Control and Prevention said of how the man fled when U.S. health officials tracked him down in Rome and told him not to get on an airplane. "There will be many lessons learned from this."

The CDC was a step or more behind the man on his six-country odyssey, not getting his name to the no-fly list until he apparently already was en route to Canada, Cetron said.

But the CDC did get word to U.S. Customs and Border Patrol before the man and his wife crossed into the country at Champlain, N.Y., a Department of Homeland Security spokesman told The Associated Press on Wednesday.

Customs "is reviewing the facts involved with the decision to admit the individuals into the country without isolation," a spokesman said.