Monday 19 May 2014

A matter of time before MERS hits Singapore

MOH points out risks associated with being an air travel hub, but says hospitals are vigilant and prepared
By Linette Lai, The Sunday Times, 18 May 2014

It could simply be a matter of time before Singapore gets its first case of MERS.

"Being an air travel hub, there is always the risk that eventually we will also report a case," said Dr Jeffery Cutter, director of the Health Ministry's communicable diseases division.

Already 18 countries have registered at least one patient with the Middle East respiratory syndrome (MERS), although the Middle East remains the worst affected.

From today, air travellers arriving from hot spots Saudi Arabia and the United Arab Emirates, as well as other MERS-affected countries from the Gulf region will have their temperature screened.

But even if a case of MERS is detected in Singapore, the likelihood of a community outbreak is low, said Dr Cutter.

This is because sustained transmission of the disease - when a person passes the virus to those beyond his immediate circle - has not been observed.

Instead the spread of MERS overseas has been concentrated in hospitals, unlike the severe acute respiratory syndrome (SARS) outbreak here in 2003, which spread mainly in the community.

That is why local hospitals have been urged to "stay vigilant". They have already put in place plans to deal with patients suspected of carrying the virus.

At Tan Tock Seng Hospital (TTSH) and the Singapore General Hospital, for instance, all emergency department patients will be screened and put in isolation rooms if they are suspected to have the virus.

TTSH is one of the first places air travellers will be transferred to if they are suspected to have MERS. It also has plans to increase facilities for screening and admission "if and when the number of suspected patients increases", said a hospital spokesman.

In the event of a confirmed MERS case here, contact tracing will be carried out by the Ministry of Health (MOH). Those identified will be quarantined for 14 days, which is how long the virus takes to incubate.

While younger people were more susceptible to the SARS virus, MERS seems to target older people with chronic diseases. However, experts say too little is known about the disease to come to firm conclusions.

"It's not that there's not enough work being done, but it takes time for all this to be fully understood," infectious disease expert Ng Oon Tek of TTSH said.

Laboratories in Singapore are able to effectively test for the disease. This means confirmed cases can be detected quickly.

"When SARS emerged in 2003, we knew a lot less about the virus initially," said Associate Professor Benjamin Ong, director of medical services at MOH. At the time, he recalled, suspected cases were identified based on symptoms such as fever.

"But because fever is relatively non-specific, it also meant that we ended up with a lot of noise that we had to screen through."

Whether precautionary measures are stepped up will depend on the MERS situation abroad, Prof Ong added.

"The more we know, the more we will be able to calibrate our responses," he said. "Stepping up does involve a fair bit of resources and a little bit of inconvenience for people... so we have to make the decision carefully."

A more effective killer than SARS
By Melissa Sim US Correspondent in Washington, The Sunday Times, 18 May 2014

A growing number of people are being affected by the Middle East respiratory syndrome (MERS), but the international health authorities have yet to declare a worldwide emergency.

On the face of it, there appears valid reason for concern.

When compared to the severe acute respiratory syndrome (SARS), MERS is a far more effective killer.

So far, about a third of all MERS patients have died. For SARS, less than one-tenth succumbed.

There is currently no specific treatment for MERS, nor is there a vaccine. The best a person can do, experts say, is to seek medical advice early so doctors can address any complications such as pneumonia, should that develop.

Still, the health authorities have resisted pressing the panic button.

"When all the countries were looked at... we don't see any evidence of community infection sweeping through," said Dr Keiji Fukuda, assistant director-general for Health Security at the World Health Organisation (WHO).

Using the example of the flu, he added: "Typically, when we see an influenza season, for example, we will see a sharp rise and many people getting infected and it's clear you get infection going through communities. We don't see that."

The lack of a travel advisory against visiting Saudi Arabia and the Middle East, where MERS is believed to have originated, means there is no clear indication yet whether thousands of people heading to Saudi Arabia for the main Muslim pilgrimage season in October will be at risk by making the trip.

When asked specifically about the haj, WHO spokesman Tarik Jasarevic said that although there are no WHO travel restrictions, the Saudi Ministry of Health has recommended that the elderly and those with chronic disease postpone going on the pilgrimage.

Echoing the WHO, the Centres for Disease Control and Prevention in the United States said it "does not recommend that travellers change their plans because of MERS", as most instances of person-to-person spread have occurred in health-care workers and others such as family members of caregivers of those with the virus.

Epidemiology professor Stephen Morse from Columbia University's Mailman School of Public Health said the mass gathering during the pilgrim season could increase the spread of MERS due to close proximity between people.

But he added that more important than telling people to stay away, is telling people to be watchful for signs of the virus, as early detection can help save lives.

At this point, medical experts say they are not yet certain how the virus spreads.

Dr Fukuda adds that while the situation has become more serious, there is no evidence of sustained human-to-human transmission. In other words, it is not yet a pandemic.

The best guess of doctors right now is that the virus is carried in water droplets, spreading through exposure to an infected person who is sneezing and coughing.

Yet, it seems this only happens after prolonged exposure. People seem to have low risk of contracting the disease through casual contact. For example, although one infected American health worker travelled on a crowded flight from Saudi Arabia to the US, no other person on the plane has been diagnosed with MERS.

Prof Morse said MERS is not yet more contagious than SARS, but that could change, especially if the virus mutates.

"This is a dynamic picture... We don't know enough of how people get it, it's very unclear," he said.

Free flow of information key in battle against MERS
By Andy Ho, The Straits Times, 17 May 2014

AFTER an emergency meeting recently, the World Health Organisation (WHO) is urging countries to be more vigilant against the Middle East respiratory syndrome (MERS) coronavirus.

More than 500 confirmed MERS cases are all connected to the Middle East, and the virus has been exported to several countries.

The world health agency became more concerned after April saw a spike of 288 MERS cases compared to 207 confirmed cases from March 2012 - when MERS first emerged - up to March this year. In Jeddah, there were 135 cases in April alone, compared to just four in the previous two years.

However, WHO says an epidemic is not yet imminent.

That means the recent surge in cases does not indicate that the virus has mutated into a form more transmissible from person to person. The uptick is probably a seasonal increase in the number of primary cases, it says.

These are people infected with MERS from animals, likely camels which themselves were likely to have been infected by bats.

The seasonal increase may be related, in this instance, to the movement of large numbers of camels both to and from Saudi Arabia's Hafr Al-Batin region for a large annual camel fair.

But this seasonal increase in primary cases of animals infecting humans may be further amplified when patients then infect health-care workers - if hospitals are slack in their infection prevention and control measures.

Still, within the community at large, MERS is not being transmitted rapidly from person to person for now.

Following lessons learned during the severe acute respiratory syndrome (SARS) crisis, the scientific community has worked together to develop the tools to sequence and track the evolving virus, so MERS diagnostic kits are already available.

The scientific community is also largely sharing the viral DNA sequences on the Internet.

Based on these sequences, some scientists think human-to-human transmission may have increased, contrary to WHO assurances.

They note that the virus isolated from six patients of four hospitals in two cities - Jeddah and Mecca - in April had matching DNA sequences, which also matched three earlier cases from Jeddah. The similarities, they think, suggest primary infections that are human-to-human, not camel-to-human.

Other experts counter that the viral DNA sequences' coding for what is known as the spike protein - the part of the virus that binds to human cells and enables it to infect people - have shown no mutations in all available specimens so far.

In fact, the rest of the virus genome has also changed little from that isolated from the world's first case in 2012. Overall, then, the virus genome is still stable.

Genomics aside, scientists are also mathematically modelling the situation using available epidemiological data about the cases and all their human contacts.

A virus' epidemic potential is measured by the average number of humans infected (secondary cases) by one human case (the index case).

This measure is called its reproduction number (R). If R is below one - that is, on average, each index case is spreading to fewer than one person - the virus is unlikely to cause an epidemic.

But if R exceeds 1, cases could grow to cause an epidemic.

Modelling by most experts finds the R for MERS to be presently under 1, at say, 0·69, in the current pre-pandemic stage.

On a study trip to Saudi Arabia in late April, scientists from the European Centre for Disease Prevention and Control looked at 26 index cases and 280 close contacts, of whom only nine were confirmed to be infected. It reckons that this means an R of just 0.3.

These figures apart, how much like SARS will MERS be?

Though both are coronaviruses, they differ in their biology. For example, their spike proteins latch on to different receptors in human cells.

While SARS took only months to adapt its spike protein to human cells, MERS has been circulating for two years among humans without doing so.

In that time, it has not yet mutated into a pandemic form.

Why? The rate of mutation depends on many variables that may differ between China and Saudi Arabia. These include the different animal hosts involved (from bats to civet cats to humans in SARS but, most likely, from bats to camels to humans in MERS) and population density.

Also critical is political willingness to be forthcoming about an epidemic, which affects the timeliness in taking baseline preventive measures.

Then there is the R before the pandemic actually begins.

For SARS in 2002, it was 0·8. It is lower for MERS at present, approximately 0.3 to 0.69 by some estimates.

But because far fewer MERS virus samples have been sequenced and shared on the Internet than SARS, whether the virus has already adapted to human beings yet can't be ruled out.

Since their mutation rates and pre-pandemic R clearly differ, any comparison of SARS and MERS must be circumspect.

In what is potentially a public health emergency, the sharing of both epidemiological and genomic data is important.

During SARS, China initially hid the patients and refused to share epidemiological data and viral sequences on the Internet for scientists in other countries to study.

Saudi Arabia has been doing better. But already, there are signs of internal rivalry.

Dr Ziad Memish who is its assistant deputy health minister for preventive medicine, and an infectious disease specialist-cum-epidemiologist, has built up a lot of knowledge about MERS in the last two years, and developed a network of contacts that could make a difference in a pandemic.

But in recent weeks, he was left out of a new MERS advisory committee set up by Saudi health minister Adel Fakieh, a decision that raised eyebrows.

As China's experience with SARS shows, expert knowledge and politics must come together. The world would hope that internal politics do not result in an unnecessary gap in Saudi Arabia's defences against the virus.

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