(AP) - The leader of an international team helping Mexico face down the swine flu outbreak said it should soon learn whether the epidemic is stabilizing, but with global apprehension on the rise, Hong Kong sealed 350 tourists and employees inside a hotel.

Dr. Steve Waterman, the head of a team from the Centers for Disease Control and Prevention, warned against taking false comfort from the fact that only one person has died outside Mexico, saying more deaths are likely as the epidemic evolves.

"That is the big question: Is it stabilizing or not? And it is too early to say, but I think we are getting systems in place where we are going to be able to get a handle on this soon," Waterman, standing amid CDC doctors and specialists at the Mexico City nerve center where officials are confronting the outbreak, said Friday.

Mexican officials have been cautiously optimistic that the worst is over here, even as the government took additional protective measures Friday by beginning a five-day shutdown of all nonessential government and private business.

In New York City, which has the most confirmed swine flu cases in the United States with at least 62, swine flu has not spread far beyond cases linked to one Roman Catholic school. The U.S. case count rose to at least 160, based on federal and state tallies, although state laboratory operators believe the number is higher because they are not testing all suspected cases.

The virus has also been detected in Canada, New Zealand, China, South Korea, Israel and eight European nations.

China was suspending flights from Mexico to Shanghai because a case of swine flu was confirmed in a passenger on a flight from Mexico, China's state-run Xinhua News Agency reported. Singapore announced a week-long quarantine for anyone arriving from Mexico.

The Hong Kong hotel was sealed after a Mexican tourist who recently arrived fell ill - Asia's first confirmed case of the swine flu strain.

Waterman, whose team is working with Mexican officials, said the scientists are trying to determine the mortality rate of the virus, and don't yet know where it started or why. But he and other experts said it appeared the outbreak could have been far more deadly, particularly in the teeming streets of Mexico's capital.