Thousands of customs and immigrations inspectors and other federal homeland security workers are being trained to spot symptoms of SARS (search), and they have orders to detain people with symptoms of the highly contagious illness.

The training is part of the government's effort to prevent an outbreak in the United States of severe acute respiratory syndrome.

Officials said travelers would be detained if they had possible signs of SARS, including high fever, dry cough, breathing trouble, or if they said they are experiencing these symptoms. A public health official would be summoned to give a medical evaluation.

Homeland Security Department (search) spokesman Dennis Murphy said 22 major U.S. airports, including Kennedy International in New York and Los Angeles International, have public health officials on site. Murphy did not provide a list of the airports, but he said others among them were Seattle, Chicago, Miami and Dulles, outside Washington, D.C. Other airports, he said, have health officials on call.

Murphy said he was not aware of a traveler being detained against his or her will for a suspected case of SARS as a result of his department's heightened vigilance.

Julie Gerberding, director of the Centers for Disease Control and Prevention (search), said quarantine officials have been stationed at airports for decades to detect disease and are sensitive to the inconvenience of detention. "We really do try to be respectful of citizens rights," she told a House Energy and Commerce subcommittee.

Robert Bonner, commissioner of the department's Bureau of Customs and Border Protection, said special attention was being given to passengers arriving into the United States on 51 daily flights from Asia, including Hong Kong, Singapore and Beijing.

"We have the authority to detain any individual who appears to have SARS, and we can, will and should exercise that authority," Bonner said.

There are 63 probable U.S. cases of SARS, the CDC says.

The disease has peaked in Singapore, Hong Kong and Toronto. In China and Taiwan, cases are increasing.

"China has the resources necessary to deal with this," David Heymann, head of the World Health Organization's communicable diseases program, told the House Energy and Commerce Committee. "But public health has been neglected in China. ... We don't know if China will commit the full resources necessary."

Hong Kong has installed an infrared system to try to detect incoming travelers who have a fever. So far 37 have been identified and it is something the agency is watching to see if it will be useful in the future, Heymann said.

Noting that the University of California has refused to admit 500 students from China for summer school this year, Rep. Ed Markey, D-Mass., asked Heymann about the proper criteria for turning people away. Heymann said guidelines include whether they have had contact with a SARS patient or if they've been in a hospital that treats SARS within the previous 10 days.

The U.S. training sessions to spot SARS have been going on for about a month, largely set in motion by an April 4 executive order by President Bush that gave federal health officials authority to quarantine people sick with SARS, Murphy said.

The Bush order stems from an incident in which a traveler arriving in the United States with some symptoms refused detention and got on a train for further travel. Health officials had to scramble to see who the traveler may have exposed before determining he did not have SARS, Gerberding said.

Involved in the effort are customs inspectors, immigration inspectors, workers who screen people and baggage at airports and employees who work at detention centers, where people caught entering the United States illegally are taken.

"We've issued instructions essentially telling our people at borders, airports and detention centers to be on the alert for people exhibiting symptoms," Murphy said.

The department has made masks and gloves available to workers if they encounter someone with SARS symptoms, Murphy said.

The CDC's Web site says the primary way that SARS appears to spread is by close person-to-person contact. That includes touching the skin of other people or touching objects that are contaminated with infectious droplets -- left behind when someone infected with SARS coughs or sneezes -- and then touching your eye, nose or mouth. It also is possible that SARS can be spread more broadly through the air or by other ways that are not currently known, the CDC says.

The CDC says most of the U.S. cases of SARS have occurred among travelers returning to the United States from other parts of the world with SARS.