Singapore has launched several emergency measures to contain a possible return of the deadly SARS after the detection of a fresh case almost four months after the epidemic wreaked havoc in the region.

SARS attack: The complete coverage

SARS killed 33 people in Singapore and plunged its economy into a disappointing growth rate.

A final confirmation if the fresh case is of SARS and if it an isolated one will be known after tests at a US laboratory by September 22 -- which is 20 days and two SARS incubation periods since the patient developed the symptoms.

As the Singaporean authorities confirmed on Tuesday that a 27-year-old researcher has been infected with SARS, the stock market plunged to a four-week low. Airlines and tourism stocks were the worst hit.

The plain speaking acting health minister of Singapore Khaw Boon Wan said: "I don't think Singaporeans need to lose too much sleep over this. I myself have not lost too much sleep over this. But this doesn't mean that we are complacent."

Having learnt some tough lessons from their delayed response to the SARS outbreak early this year, Singaporean authorities are this time overcautious.

Over 25 people who came into contact with the SARS patient after August 26, when he developed fever, have already been quarantined. Others are being traced.

The patient had seen doctors at the Singapore General Hospital. He has now been shifted to Tan Tock Seng Hospital's Communicable Centre 2.

Two wards of hospital, where the patient has been kept, are out of bounds for visitors.

The two laboratories-- National University of Singapore and Environmental Health Institute-- where the patient was doing research on West Nile virus have suspended work and investigations are on to see if the patient came into contact with the virus at these labs. Both the labs have strains of SARS in its custody.

The World Health Organisation, which recently warned of a possible return of SARS, said it has no plans of issuing a travel warning.

The WHO spokesman for Western Pacific was quoted as saying that they believe it could be 'an isolated case.'

Thousands who throng this shopping heaven too seem to believe the same. The splendid shopping malls here are now beginning to see the return of crowds, a sizeable number of them  from India.

"I am not scared," Shalu Mehta, a middle-aged woman from New Delhi, said in a heavy Hindi accent as she went around shopping with her husband in Mustafa's, a 24-hour mall.

A sales manager at Mustafa's said the "people are back, we don't see any panic."

But there are some who are clearly concerned. Boon Haw, a 42-year-old taxi driver, said he is praying "that SARS goes away."

He drives a shared cab from the airport and has to pay Singapore dollars 120 per day to the cab company. "I was running on loss all through the SARS period and then Iraq war too hit tourism badly. I have just started making some money," he said.

Singapore's neighbours too are concerned. Hong Kong, Thailand and others are putting in place screenings for visitors from Singapore.

Several corporates in Singapore have also initiated temperature check for their employees twice daily.

Acting Health Minister Khaw Boon Wan is satisfied with the response till now: "I think, in many hospitals, in many other countries, this case may have been missed completely."