Limiting The Transborder Spread Of Sars In And Out Of Singapore

08 May 2003

By Dr Balaji Sadasivan

Let me start by stating the current situation in Singapore. The last reported SARS case not occurring in a defined setting was on April 14 or more than 20 days ago. The Communicable Disease Centre (Atlanta) has lifted its travel advisory on Singapore. There is only a travel alert now. The date of onset of the last probable case of SARS in Singapore was on 27 April or 11 days ago. Things look much better today than they did two weeks ago.

This does not mean that we can let our guard down. SARS is a global problem and Singapore has instituted measures to minimize the transborder transmission of SARS.

Preventing the Import and Export of SARS

Singapore has implemented measures to ensure that SARS is not imported or exported. At the Changi Airport, we are screening all passengers and crew departing from Singapore, as well as those arriving from SARS-affected areas, with thermal scanners. With the availability of more scanners from mid-May, the temperature screening will be extended to all arrivals, including transit and transfer passengers. We are also progressively conducting temperature screening at the Woodlands and Tuas Checkpoints, as well as the sea checkpoints.

All travellers arriving in Singapore are issued with health advisories on SARS and are asked to fill in health declaration cards. For any traveller who is detected through the temperature screening as having a fever, he/she is offered free SARS screening at Tan Tock Seng Hospital, similar to Singaporeans.

Should any traveller be diagnosed as a SARS case after being screened at Tan Tock Seng Hospital, contact tracing will be activated to establish his/her contacts quickly. For Singaporean and foreign contacts with local residences, they will be issued Home Quarantine Orders. For foreign contacts who leave Singapore within 48 hours (the incubation period for SARS is 2-10 days), the relevant foreign authorities will be notified through the World Health Organisation, so that contact tracing there can be activated if necessary.

As of 6 May, about 70,489 people have been screened at Changi Airport. Of these, 58 were referred to Tan Tock Seng Hospital for further examination. Out of these, 56 were cleared of SARS and discharged. Two passengers are still warded. Both are currently warded as observation cases.

Because of our extensive screening thus far, we have been able to limit the transborder spread of SARS. For example, one of the passengers mentioned above was on board a flight from Hong Kong to Melbourne on 27 April and was on transit in Singapore. His fever, which had started the previous day, was detected by the thermal scanner. He was transferred to Tan Tock Seng Hospital for observation. He was diagnosed as a suspect SARS case on 28 Apr. If we had not screened that flight, he would have gone on to Melbourne. So although the traveller may not originate from Singapore, by our actions, we are reducing the risk of transborder transmission to other countries.

Communicating What We Know

Our approach has been to err on the side of caution, to communicate as much as possible what we know so that necessary precautions can be taken to safeguard the community in Singapore as well as communities overseas. In the fight to contain SARS, knowledge is a key weapon. However, we need to communicate based on facts. We have consistently followed this policy.

For instance, even before the word SARS was coined, there was the case of the Singaporean doctor who had treated one of the first index cases in Singapore from 1-8 March. He developed fever and while symptomatic, flew to New York on 11 Mar. When he sought treatment at a private clinic there, his chest X-ray showed he had pneumonia. He called back to inform a colleague in Tan Tock Seng Hospital who in turn alerted the Ministry of Health. When we learnt that he was already on a flight back to Singapore via Frankfurt, we quickly notified the German Health Authorities, so that they could make preparations two hours before he arrived.

There was also the case of a Singaporean professor who died of a-typical pneumonia on 25 Apr. He had met with two visiting American professors a week earlier. The university quickly contacted the American professors to check on their health. Subsequently, when the autopsy showed that the case was not due to SARS, the American professors were also updated.

Cases of Foreigners Contracting SARS

We investigate every foreign case of suspected or probable SARS, whereby the person has a travel history to Singapore. We want to explain the process of transborder contact tracing and clarify some cases that have been reported in the media lately.

As part of investigations into foreign cases of suspected or probable SARS, contact tracing is carried out to identify all possible sources of infection and to prevent further spread of infection. We work with relevant authorities in other countries or the World Health Organization to determine crucial information such as the dates of stay in Singapore and the date of the onset of SARS.

Contact tracing is an important medical tool in the control of SARS. The fact that the tracing occurs over borders does not reduce its importance. It is done in order to locate the source of infection so that other cases can be identified and if found, ring fenced so that transmission can be prevented. The case definitions of SARS are important medically and scientifically. If a SARS case is called non-SARS, the danger is obvious. But when a Non-SARS case is called SARS, there is also damage. Resources will be used wrongly and the public will be misinformed. It may trivialize the illness with subsequent dangerous consequences.

The following are examples of cases we have investigated.

Many in the British media reported on the experience of a 60-year-old Briton who claimed that she caught SARS during her 17-hour stopover in Singapore in March. It was reported that she first saw a doctor on 2 April and was confined to a hospital isolation ward for nine days at the North Manchester General Hospital for observation. Her case was considered "probable" because her second X-ray in the hospital showed a shadow in her lung area. We contact traced all her movements in Singapore and did not find any sources of infection. Officers from the High Commission of Singapore in London have also spoken to the lady on two occasions. She is well now and we are awaiting the final blood test on 29th May for confirmation.

On 3 May, it was reported that a Qantas flight attendant was hospitalised as a probable case of SARS at St. Vincent's Hospital in Sydney. She was in Singapore from 25-26 April and arrived in Sydney on 27 April. She developed fever on 3 May, and was admitted to the hospital on the same day. When we knew about the case, we contacted the doctors in Australia looking after her to obtain more information. She was discharged on 5 May and the diagnosis at the time of discharge is a non-specific viral infection (not SARS).

In the US, there was a reported case of a grandmother who had visited Singapore on 19 Mar for a four-hour layover. Upon returning to Florida, she developed a cold but she is recovering well now. Officers in our mission in the US spoke with Dr Sherry Zahn from the Florida Department of Health, the Communicable Disease Centre, in Florida. Dr Zahn's assessment is that the chance of the lady getting SARS is very minimal and they are just being careful.

The Indian media reported that there was a groom and more than a dozen guests at his wedding who were quarantined in Western India after his bride was diagnosed with SARS. Indian health officials were quoted as saying that the bride's brother tested positive for SARS after arriving for the ceremony from Indonesia via Singapore. His flight stopped over in Singapore for a few hours on 8 Apr. WHO officials reported shortly after this story broke, that there were no confirmed cases of SARS in India. Our Mumbai Consulate has also reported that the family members were discharged from hospital on 30 Apr.

The point of highlighting these cases is to explain that we take each case reported in the media seriously and we consult the relevant authorities and weigh the evidence before closing each case. It may be difficult at times for media to have a complete story when the events occur across borders. As with the local cases, we will share with the media information on foreign cases in an open and transparent manner.

As members of the global community, all countries should co-operate with each other and with WHO, so that we can minimize the risk to each other and make travel safe for all.