Photo of SARS coronavirus. Almost 10 years after the outburst of SARS, a new SARS-type virus has emerged in the Middle East and has already proven itself to be lethal. Reuters

A new strain of the deadly virus, which unleashed SARS on the world, has emerged to re-open old wounds in Hong Kong. As the 10th anniversary of one of the territories' most fearful episodes of modern health history approaches, Hazel Parry asks, "Is history about to repeat itself?"

It was on November 16, 2002 - almost exactly 10 years ago - that a farmer died from what appeared to be an influenza-type illness in the First People's Hospital in Foshan, Guangdong province.

At the time, his death, albeit a tragedy for his family, appeared unremarkable. He had symptoms of flu with a high temperature, dry cough and respiratory problems. He looked initially to be one of the unfortunate victims who succumb every flu season.

But far from being unremarkable, the farmer's death marked the beginning of an outbreak of a new and highly contagious disease which, within eight months would kill more than 8,400 people, including 300 in Hong Kong and 349 on the mainland.

The Foshan farmer has since been identified as patient zero, the first known case of Severe Acute Respiratory Syndrome (SARS), a disease caused by a strain of the coronavirus, a large family of viruses also responsible for the common cold. The present strain, originated with bats.

The months that followed were a time of growing fear and disruption in Hong Kong, as the number of infections climbed and more people died. People panicked and bought surgical masks in bulk, whole families and communities were quarantined, schools were closed, Hong Kong was declared a no-go area for tourists and the economy nose-dived, as the fear or the unknown hit stocks and property prices.

SARS peaked at the end of March in Hong Kong with an outbreak among the community in Amoy Gardens, which infected 329 residents, killing 42. But within weeks it was on the decline and by the beginning of May, only a handful of cases were being reported daily compared to 30 to 40 when it was at its peak. To the relief of Hong Kong, the territory was declared officially free of SARS on June 23, 2003.

Now, almost 10 years after the Foshan famer's death, a new SARS-type virus has emerged, which has already proven itself to be lethal.

So far two cases of the new SARS-type virus have been confirmed, both of which originated from the Middle East. The first case occurred in a 60-year-old Saudi Arabian national who died in June this year. The second, a Qatari man, aged 49, who had travelled to Saudi Arabia recently, is currently being treated in hospital in the UK.

At the weekend, news of a suspected case in Hong Kong put the city on high alert. A four-year-old boy developed symptoms shortly after arriving here from a visit to Saudi Arabia last Wednesday. For 48 hours Hong Kong feared the worst, until Monday when the government confirmed the case to be one of swine flu rather than the new SARS-type virus.

However, the scare has been enough to re-open old wounds in Hong Kong and left many people pondering the questions: How similar is this new virus to SARS and is history about to repeat itself?

The emergence of the new virus - which has been named betacoronavirus 2C - is being treated seriously by the medical world since it was first reported by the World Health Organization (WHO) on September 23.

In response, the WHO has issued a global alert with guidelines on identifying and diagnosing the virus.

In Hong Kong, the government has reacted by listing the "severe respiratory disease associated with novel coronavirus" to the list of infectious diseases as a statutorily notifiable disease under legislative amendments gazetted on September 28.

This will require all doctors and medical professionals to report any suspected cases.

It has also convened meetings of its Scientific Committee on Emerging and Zoonotic Diseases of the Centre for Health Protection (CHP) to assess the risk and local response to the virus.

At a meeting held late last month, the committee concluded that although the new virus is genetically distinct from the SARS-coronavirus of 2003 and there was little evidence to show it was capable of passing from human to human, there were still uncertainties surrounding the virus which made surveillance crucial.

CHP Controller Thomas Tsang has promised vigilance and enhanced surveillance on multiple fronts to allay any public fears.

"These include the setting up of an enhanced surveillance mechanism with public and private hospitals, practising doctors and the airport for any suspected cases of novel coronavirus infection, especially among returning travelers from the Kingdom of Saudi Arabia or Qatar," said Tsang.

Tsang said research already carried out on sequencing the virus in London, would allow them to confirm any diagnosis of the disease within two days of its being reported.

Letters have also been issued to travel industry, airlines, schools and elderly homes to inform them of the latest situation and provide them with infection control guidance and related health advice, he said.

"The situation is dynamic and more developments may take place in the coming days and weeks, as more findings come to light. We will update the public frequently," said Tsang.

It is indeed a dynamic situation with many questions regarding the virus still to be answered. What is known at present is that the virus is 90 percent similar to the SARS coronavirus. Like SARS, it also is believed to have originated from bats, somehow mutating to allow it to cross the species barrier.

Symptoms too are almost identical to SARS with those infected suffering from fever, cough, shortness of breath, and breathing difficulties. The death of the first victim also implies it may be as equally as deadly as SARS which carried a mortality rate of up to 12 percent among those infected.

Unlike SARS, however, the early research suggests that this virus has not mutated into a form which allows it to be passed from person to person.

According to SARS expert Dr Malik Peiris, the scientific director of the HKU-Pasteur Research Centre, it is this factor which is key to determining how much of a threat the virus really is and whether it is a new SARS in the making.

"The key question is: Where did these two patients acquire their infection from? Was it from animals to humans? Or is there human to human transmission?" said Peiris.

"If there is no human to human transmission then in a sense, it is similar to a virus like H5N1 avian flu and although that is bad in that it spreads to humans, the risk is not high.

"If there has been human to human transmission then that is quite a different scenario.

"However, from the information we have so far, there is no evidence to indicate human to human transmission. This is certainly the case if we look at the health care workers who are in contact with this patient and who have not been infected.

"This is a marked difference from SARS which, if you remember, resulted in many health workers becoming infected."

Peiris, who played a key role in identifying the SARS coronavirus of 2003 and in avian flu research in Hong Kong, is currently involved in research on the new virus and is in contact with counterparts in the UK and the Netherlands.

Peiris claims one advantage the medical world has today, compared with the outbreak of 2003, is the heightened knowledge and infectious disease surveillance which grew out of the SARS experience.

"It is early days yet with regard to this novel coronavirus, but we know much more about coronavirus now than we did 10 years ago," he said.

"When SARs emerged, although we identified it as being in the coronavirus family, it stuck out a mile as being different. There was no known, close relation to it anywhere. It was a mystery as to where this virus emerged.

"Before SARs there were only two known human coronavirus which were the cause of the common cold. In fact the coronavirus family was thought not to be a serious problem because it caused the common cold and that was it.

"The emergence of SARS changed that whole perception and as a result of SARS, much more research has been done on this group of viruses.

"Following that attention, a whole bunch of coronaviruses have been discovered, particularly in bats and also other mammals. There has also been two new coronaviruses discovered in humans called NL63 and HKU1.

"Unlike SARS, these two viruses are not new and have been circulating for a long period of time but never previously been detected.

"Now we have yet another coronavirus affecting humans. Whether it turns out to be a virus that has been circulating in humans for some time, remains to be seen but my own suspicions are that like SARS, it is a newly emerging one."

This increased knowledge had been instrumental in the early identification of the new virus. Likewise, SARS also played a role in improving global surveillance and monitoring of infectious disease, said Peiris, with international health regulations now making it mandatory for countries to make an effort to diagnose, identify and report disease outbreaks.

"I wouldn't say there wasn't alertness at the time of SARS and if you remember the World Health Organization was quick to create a network and provide daily updates that led to the identification of the virus, diagnostic testing and controlling the threat.

"But the knowledge base and alertness, surveillance and global sharing of information is much better now and this allows people all over the world to be alert to this new virus and make information available so it can be monitored better."

Peiris explained that research so far had identified the nearest relative of the new virus to a coronavirus found in bats in Hong Kong and throughout Asia.

SARS was also found to originate from bats but then adapted to infect first civet cats which were widely sold for their meat in wet markets in China. From there, the virus adapted again infect humans and then again to acquired the ability to transmit from human to human.

To do so, the virus had to undergo a long process of adaptation, says Peiris. If the new virus was currently not able to transmit from humans, it would have to undergo a similar and complicated process of adaption to become a threat on the scale of SARS.

Peiris believes the removal of civet cats, the so-called amplifiers of the bat virus - from markets in China played an important role in preventing the re-emergence of SARS since its disappearance in the summer of 2002.

"The key point is that new viruses that jump from animals do occur from time to time. There are other viruses that have jumped from animals to humans but then there was no further transmission. If that is the case with this new virus, then there is really no cause for public concern.

"That doesn't mean that such an event cannot happen again but it is not easy for a bat virus to make that change," said Peiris.

The announcement on Monday, that the four-year-old boy did not have the new SARS-type virus must have come as a relief to all those who remember with fear the outbreak of 2003.

But as Peiris says, it is very early days and as yet scientists are not fully aware of what this virus is capable of.

Only time and extensive research will answer all those unanswered questions and determine for sure whether this new virus is like SARS in a different guise and a new killer is on the loose. In the meantime, say the experts, both internationally and locally, the world must stay alert with the best weapon of defence being continued surveillance and global cooperation.

(HK Edition 10/10/2012 page4)