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How Much Do You Know About the Mysterious MERS Virus?

04/26/2014 02:51 EDT | Updated 06/26/2014 05:59 EDT
FAYEZ NURELDINE via Getty Images
Egyptian medical workers wear masks as they leave the emergency section in King Fahad hospital in the city of Hofuf, 370 kms East of the Saudi capital Riyadh, on June 16, 2013. Four people have died from the MERS virus in Saudi Arabia, bringing the death toll from the SARS-like virus in the kingdom to 32, the health ministry said. The World Health Organisation announced that the global death toll from MERS had reached 33, with 28 of them in the kingdom. The virus is a member of the coronavirus family, which includes the pathogen that causes Severe Acute Respiratory Syndrome (SARS). AFP PHOTO/FAYEZ NURELDINE (Photo credit should read FAYEZ NURELDINE/AFP/Getty Images)

Over the last few years, the world has been gripped with the news of viruses, whether known or emerging, causing epidemics in certain parts of the world. Inevitably, when this occurs, a familiar question is asked: "Will this cause a pandemic?"

It's an entirely understandable query. After all, when avian flu first appeared in 1997 health officials were completely unprepared. A few years later, SARS practically shut down the city of Toronto and put the entire province of Ontario on lockdown. Then, in 2009, when a pandemic actually occurred thanks to the H1N1 flu virus, Canada was hit relatively hard with some 10 per cent of the population infected and 428 deaths. Then there are the recent close calls of imported H5N1 earlier this year and the suspected case of Ebola just last month (which was thankfully negative).

Now there's a new virus making headlines. It's called the Middle East Respiratory Syndrome Coronavirus although most people truncate that to the simplified MERS. Not to be mistaken with the Mortgage Electronic Registration Systems, which some believe is a silent economic pathogen, this once quiet virus is making noise as it spreads throughout the Kingdom of Saudi Arabia and hitches rides to several other countries.

The numbers are changing daily but to date it has infected over 200 people and killed just over a quarter of them. In public health terms, on a scale of 1-10 in terms of concern, this would be an 11. As expected, the data once released has sent worries of a pandemic travelling through the airwaves and the internet. In the meantime, public health officials have worked diligently to determine the nature of the epidemic and more importantly, how to keep it from going global.

Using the tenets of epidemiology, which are akin to deduction devices of Sherlock Holmes, these disease detectives have done their darnedest to learn as much as they can so we can all be safe. Although the conclusions are far from over, what we have learned so far may offer some peace of mind and the realization this most likely will not be a pandemic.

As with any murder investigation, in this case microbial, the first order of business was to identify the culprit. In the case of MERS, this happened back in 2012, when a group in the Netherlands isolated and examined the nature of the virus. It was a coronavirus, which puts it in the same family as the common cold and SARS. But further study of the virus revealed it was unlike either - it was more deadly than the common cold and it had a different biology than SARS. This meant a new type with presumably different traits.

The next step was to determine its modus operandii - how it infects and kills. With both studies of the clinical cases and work in the laboratory, researchers determined how the symptoms of lung infection, pneumonia, diarrhea and eventual collapse are caused. The virus attacks cells possessing a protein known as depeptidyl peptidade 4 (DPP4), which is found in the deep part of the lung, the intestines and many other parts of the body. It then travels throughout the body leading to organ failure and eventual need for intensive care. Eventually, the virus wins and the patient dies. The data also suggested the presence of pre-existing conditions, such as diabetes, cardiovascular disease, kidney disease and respiratory problems could lead to worse outcomes.

With the biology figured out, the next question was whether MERS could be transmitted from human to human, a necessity for any pandemic. The answer was bittersweet. Although some cases spread between humans, they all happened in close contact, usually in the home or the hospital, not in the open space of a market or religious structure. This meant the virus was capable of spread but was limited. Though this meant people would have to rely on hygiene and infection control to keep the virus from spreading, in the context of a pandemic, this was entirely good news.

The last part of the analysis was identifying the source of the outbreak. Originally bats were believed to be the primary source of the virus and interaction with them would lead to infection. However, this type of contact could not account for the number of cases. Then earlier this year, the virus was found in a much more domesticated animal: the camel. In Saudi Arabia, these animals are a part of everyday life for many; the virus could easily transfer to humans. However, this raised a question concerning the numbers of infected individuals. If so many people were interacting with camels, then why were the numbers so low?

In Saudi Arabia, this was exactly the question posed by Deputy Health Minister Ziad Memish. He wondered if perhaps they were only testing the sickest people for the virus leaving those who may have mild or no symptoms out of the statistics. Last month, he decided to test anyone who might have been exposed. Sure enough, the case numbers exploded. But, unlike the incredibly high numbers of fatalities originally recorded, the number of deaths in relation to infection dropped significantly. In addition, those who did not suffer from underlying conditions for the most part fared well and needed little to no medical intervention. Unbeknownst to everyone, MERS was spreading; it just wasn't killing.

That leaves us to today where the mystery continues although we are closing in on an answer. Eventually, the source of the virus will be found and the picture will be complete. However, what has already been learned is of incredible value. First, the virus can be easily controlled, just like the common cold and SARS. Second, healthy individuals seem to be at little risk of problems while those with underlying conditions have to be more careful; this is reminiscent of the concerns during the H1N1 pandemic. Finally, while the virus continues to be exported, there have been no transmitted cases either on airplanes or after landing; similar to the H5N1 case in Alberta.

There is little doubt the virus continues to spread but its effect appears to be limited. While the chance is always present for global spread, there are few indications this will be a killer in Canada. More likely than not, the worst case scenario would be the introduction of this virus into a highly susceptible community causing a single outbreak. While this might cause unease, just remember the same thing is happening right now in several locations across the country with another potentially lethal virus: measles.

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