Six airmen and three of their relatives have been quarantined in Texas after some reported symptoms similar to those of SARS, officials said.
The safeguard follows reports earlier this week of mild to moderate respiratory problems among military personnel who recently passed through an airport in Toronto, said Captain David May of Dyess Air Force Base in Abilene.
Only one person in the group fits the definition of a suspected SARS case, and no one has been officially diagnosed with SARS or been hospitalized, May said. All nine were under home quarantine.
May declined to say how many of the nine had been in Toronto or when. The group was in the airport for about an hour on their way to and from a military exercise in Ontario, according to the Abilene-Taylor County Public Health District.
Federal officials lifted a SARS-related travel alert for Toronto on Tuesday. The US Centers for Disease Control and Prevention said more than 30 days had elapsed since the last SARS case in the Canadian city developed symptoms. The CDC said it would monitor the situation in Texas.
Members of the SARS containment team in Toronto expressed frustration on Friday at the developments in Texas.
"The chances of this being SARS are almost beyond calculation," said Dr. James Young, Ontario's commissioner of public security. He suggested public health officials should be cautious about raising alarm about unconfirmed cases of SARS, considering the economic consequences of such reports for Toronto.
The pneumonia-like illness from Asia first was noticed in Toronto in early March.
A World Health Organization (WHO) travel advisory against nonessential travel to the city in April, along with a second outbreak in May and June, devastated Toronto's crucial tourism industry for the summer.
Hotels, airlines and restaurants report decreased business in what is usually the high season.