But the World Health Organization said it was too early to tell whether severe acute respiratory syndrome, which first appeared only six months ago in China, will establish a seasonal pattern.

Health and Human Services Secretary Tommy Thompson, who was in Brussels, Belgium, to meet European Union officials, said despite best efforts to contain severe acute respiratory syndrome, he expected it to cause deaths in areas unaffected so far.

"I am not confident at all. ... I do not think SARS is going to go away," Thompson said. "Even though it may level off now, it could come back in the fall and then you can, I think, anticipate that you will have deaths in all the continents."

SARS so far has killed at least 662 people worldwide and infected more than 7,800 - mostly in Asia. The United States has reported 67 cases to WHO but no deaths.

Thompson was on his way to WHO's annual meeting in Geneva, where health chiefs from around the world have gathered for the first time since the SARS outbreak began.

WHO experts said they are optimistic they can prevent SARS from taking root in communities and believe there is a chance they can wipe the virus out completely.

Part of the delay in recognizing SARS when it emerged in southern China stemmed from its appearance during the flu season in November and to its having some of the same symptoms as influenza, WHO officials said.

WHO scientists say there is no reason to believe SARS is more likely to occur during flu season than at any other time, but acknowledged such a relationship would be worrying because hospitals could be overwhelmed with people who believe they have SARS but who actually have the flu.

There also is no reason to believe the flu vaccination will protect against SARS because the viruses belong to completely different families, WHO spokesman Iain Simpson said.

Dr. Davey Koech, director of Kenya's Medical Research Institute, said there was a worry that SARS will recur but there was not enough evidence to make meaningful forecasts.

"Even if it is brought under control in the geographical regions where it first occurred, we know from history that that may not be the end. Very soon, you may hear of it popping up in isolated areas of the world," Koech said.

"There is no cure for it, so if it does come, there will likely be deaths, of course."

But Koech cautioned that it was "far too early" to make predictions concerning the reoccurrence of SARS.

"It would be irresponsible for anyone ... to make such predictions. We don't know the most conducive environmental conditions for it to emerge," he said.

A SARS discussion drew significant interest Tuesday at the WHO meeting, where health chiefs from around the world heard agency experts and fellow health ministers share their experiences with the new disease.

Costa Rica asked about evidence that children might get a milder infection, while officials from the West African nation of Togo asked whether airport screening measures clash with human rights.

Spain sought information on whether people infected with the virus can spread it before showing symptoms, while Nigeria was concerned about whether cultural or behavioral factors play a role in SARS infection.

Israel asked what could be done to calm anxiety and panic.