Scientists in Germany say an experimental drug for the common cold could possibly be modified for use against SARS (search), while China (search)adopted measures to prevent the illness from spreading on its vast railway network.

Rail authorities in China installed thermal scanners at some stations to check passengers for fevers and keep the disease off its trains. Officials fear SARS will spread from China's cities to poor rural regions that lack adequate medical facilities.

"The infectious outbreak is our call to arms. Time is lives," said a front-page article in the newspaper Beijing Daily.

In Hong Kong (search), where SARS has killed 227 people and infected 1,698, scientists credited quarantines for breaking the chain of transmission.

Chinese University of Hong Kong researchers say the territory's SARS outbreak is losing momentum and should dwindle by June or July and die out no later than October. For 10 consecutive days there have been single-digit numbers of new cases reported.

But Singapore, which had hoped to deem itself SARS-free as early as this week, may have suffered a setback amid news of a new possible outbreak at its largest mental health facility. Officials were expected to confirm whether the new cases were SARS later Wednesday.

The last confirmed SARS case in Singapore was on April 27, and the World Health Organization had said it would announce the city-state's outbreak was under control if there were no new cases 20 days after the last reported infection.

More than 7,500 cases of severe acute respiratory syndrome have been reported worldwide and the death toll rose Wednesday to at least 588.

In a study appearing this week in the journal Science, German researchers said they have tentatively determined the structure of a protein used by the SARS virus to infect cells. They believe the virus could be treated by a modified version of an experimental common cold drug called AG7088 (search).

Rolf Hilgenfeld of the University of Luebeck in Germany, senior author of the study, said AG7088 provides "a good starting point" for developing a drug that will block the ability of the SARS virus to reproduce.

As new SARS infections drop in some nations, Taiwan battled a tough outbreak. With 31 deaths and 238 SARS cases, the island is suffering the worst outbreak outside of mainland China and Hong Kong.

"Taiwan is going in the opposite direction," World Health Organization spokesman Peter Cordingley said Tuesday.

Train passengers have been ordered to wear masks and face fines of up to $173 if they don't.

Over 10,000 on the island are under quarantine in their homes. Taipei Mayor Ma Ying-jeou said police would be mobilized to make sure people obeyed orders to stay put.

"Because we are afraid that some people will go out at night, we will begin phoning people under quarantine between 8 p.m. and midnight tonight," Ma said.

Quarantine breakers are subject to fines of up to $8,640.

In Beijing, the city government said its economic losses were estimated at $54 million in the first four months of this year, with arrivals of foreign visitors down some 60 percent.

Beijing has been reporting a steady decline in new SARS cases, though the WHO says it is too early to say the peak of the Chinese capital's epidemic has passed.

Health officials are trying to prevent a new surge of the disease in China's poor countryside. A team of WHO investigators who returned from Hebei province, which abuts hard-hit Beijing and has reported 191 cases, said Tuesday migrant workers had taken the virus to rural areas there.

On Wednesday, China's government praised an emergency room doctor at the People's Hospital in Peking University who died of SARS.

Ding Xiulan, 49, contracted the virus early in Beijing's outbreak in March and died of multiple organ failure, the Beijing Daily said in a full-page obituary. She was at least the fourth Chinese medical worker to die in the outbreak.

Ding has been declared a "warrior in white" by the government, the newspaper said. Also Wednesday, the Beijing city government said its economic losses were estimated at $54 million in the first four months of this year, with arrivals of foreign visitors down some 60 percent.