Breaking Down Science, Step by Step

The Massive MERS FAQ

When an unknown force from beyond the edge of knowledge starts taking lives, fear is a perfectly natural response. That is the key to understanding why people were so afraid when a new coronavirus emerged from the Middle East.

Wait hold up right there, what the hell is a Coronavirus ?

Yeah, I don't blame you for not knowing about them. They mostly cause diseases in animals, and can occasionally cause colds. Up until relatively recently, there weren't any that caused horrible diseases in humans. But then a new virus emerged in 2003 causing a disease known as Severe Acute Respiratory Syndrome. The virus that caused it would come to be known as SARS.


Can you tell me more about the SARS outbreak?

We initially thought that the SARS virus emerged from Palm Civets being traded at markets in mainland China. The evidence looked good, they tested positive for the virus, and some of the people who came into contact with them got SARS. Except… the truth was more complicated than that.

You see, not long after, the virus was found in Cats, Raccoon Dogs, Platypus Bears and Ferret Badgers. I swear only one of those animals is fictional.

These animals were not the primary host for the disease either, they merely shuttled the disease form the primary host to humans. How did they do this ?


All of these animals were predators, which preyed on a specific animal which tends to carry a lot of diseases we humans find frightening.



Yes, we're talking about bats again, those flying furry vectors of disease such as Ebola and Rabies. It turned out they naturally carry lots of different coronaviruses. One strain of this virus adapted to survive within the animals that feed on bats, and as a nice by-product, these adaptations would allow it to jump into humans.

So the outbreak happened, infecting 8096 people across 29 countries, causing 774 deaths before it was contained. Once the outbreak was brought under control in 2004, SARS burned itself out, and after ten years with no new infections, it is probable that it's extinct.


But this doesn't mean that the threat is over. The vast family of coronaviruses that spawned SARS is still out there. These SARS-like viruses have been found in bat species across Europe and Africa. There was always the possibility that these could again evolve to infect humans, triggering a whole new epidemic.

In 2012, that is exactly what happened.

When did the outbreak start ?

The outbreak began in a medical facility in Jordan. In April 2012, healthcare staff working in an intensive care unit in Jordan became afflicted with a mysterious respiratory illness.


It began when a university student was taken ill with pneumonia. The two healthcare workers who looked after him soon contracted the disease. The outbreak affected eleven people. The student died, along with one of the nurses who treated him.

As mysteriously as the disease appeared, it subsided, providing no clues as to its cause. This would remain a mystery, until the next patient showed up in Saudi Arabia.


A 60 year old man developed a severe fever, coupled with a dreadful cough. His breathing problems got worse, and he was taken to a private hospital in Jeddah, where they diagnosed him with pneumonia.

It was a race against time to save his life. The doctors didn't have time to work out whether his disease was being caused by a Fungus, Bacterium or Virus. They gave him drugs for everything. Antivirals, Antibiotics, Antifungals. He got everything, and still got worse. He died within 11 days of admission when his kidneys collapsed under the pressure of both the virus and the aggressive medical treatment. The physicians were determined to hunt the virus that had caused this disease.


How did they find out about MERS ?

The answer lay in the Phlegm. Phlegm is a kind of mucus that coats the lower part of your lungs. It coats invading microbes, neutralizing them. Unfortunately, it can build up during infections, and block off small airways. Your body unblocks these airways by coughing out the phlegm, along with any microbes encased within it.


To find out what had killed this man, the researchers would have to look closely at his Phlegm. They added a sample of this phlegm to human cells, and analysed it under a microscope.

If it was a bacteria or fungus, they would be able to see the tiny bacterial and fungal cells grow alongside those human cells. No bacteria or fungi could be found, but the human cells still became damaged and sick . This could only mean one thing. It had to be a virus.


Then they hit their first wall. What virus could have caused it ?

All of their Flu virus tests turned up negative. The tried looking for adenoviruses, which can cause the common cold. Still nothing.


Then they cast their net wider, using genome sequencing to find their culprit. A coronavirus which would eventually be named the Middle East Respiratory Syndrome coronavirus (MERS-CoV).

Where did it come from?

When the Genome of MERS was sequenced, it became very clear that it was most closely related to coronaviruses found in bats. So the prophecy has come true, yet another coronavirus has jumped from bats into humans. .


After the outbreak started, various agencies set out to capture bats and test them for MERS in the areas where the outbreaks had started. They could only find one bat with MERS.

What's more, people and bats don't often hang out together. So there must be a secondary host that transmits the virus directly to people. If we can find out what this host is, we can put a stop to this outbreak.


A number of patients who had caught MERS had reported being in contact with animals such as Sheep, Goats and Camels. So naturally, these were the first to be checked from the presence of MERS.

A group from the Netherlands took blood samples from camels in Oman and Gran Canaria. They looked for antibodies directed against the MERS virus. Antibodies are proteins produced by the immune system that attach to foreign organisms, such as viruses.


If these camels would had these antibodies, it would mean that their immune system had either fought the MERS virus, or a virus that was very similar to it.

The researchers found that camels in both regions had antibodies to the MERS virus. A separate group tested camel blood samples from ten years ago, with similar findings. So it seems that not only do camels carry MERS, they've been carrying it for a long time. But antibodies alone aren't watertight evidence. It may be that the camels were infected with a virus that was looks similar enough that the antibodies constructed to fight against it also happen to attack MERS as well. It could happen.


When a farm owner who happened to keep a herd of camels came down with MERS, researchers took the opportunity to test the herd for the presence of MERS. Not only did these camels produce antibodies against MERS they also tested positive for the live virus. Subsequent studies have found that camels are host to a variety of MERS-like viruses that we didn't even know about.

It's likely that the whilst MERS is descended from those nasty bat viruses that birthed SARS, it's evolved to the point where bats are no longer the primary host. It looks like camels are the the real host for MERS.


But the evidence for this isn't very tidy. We can point to a slew of cases where we can say pretty definitively that camels transmitted the disease to humans. But then, there are other cases, where camels have tested positive for live MERS, but not transmitted to humans.


Let me tell you a story about a camel abattoir. It's where camels are slaughtered for their meat. A situation where workers get really up close and personal with all of the nasty innards of infected animals. Guess how many of those workers got MERS?

All of them ?

Nope, none of them got MERS.

How could that be ?

It is still more or less a mystery, but there are a number of factors that could come into play. Firstly, we should talk about transmission.


How does MERS transmit ?

You can get it from camels. If you drink camel milk, eat camel meat, and live in proximity with them, there is a chance of catching MERS. But focussing on those routes of transmission ignores the elephant in the room.


MERS lives in the noses and the faeces of camels, and in the lungs of humans. In order to get from point A to point B, the virus has to go through the air. So it's airborne. Researchers have found MERS in the air of camel barns in 1 out of 3 air samples. So it was there, but not in very high quantities.

So lets say that you enter a camel barn, and happen to breath in a stray MERS virus. The MERS has to take a long journey past all of your respiratory systems natural defences to reach vulnerable cells in your lungs. The virus invades cells, replicates and causes a nasty infection. That's great and all, but how does it escape the lung to infect another human ?


You already know the answer. Phlegm. It coats the viruses, sticking them together in massive globs that get coughed out. This isn't the ideal situation for the virus. It is now encased within these huge phlegm droplets, which don't stay airborne for very long.

This is why the only cases of human to human transmission occur when people are in close contact. The best chance the virus has is for you to gob these phlegm droplets on the nearest nurse.


But even then, it's an uphill struggle for the virus. There is another wrinkle to this story. Not all of the transmitted viruses are actually capable of causing an infection.


Imagine each virus has a lottery ticket. This ticket determines whether they'll cause an infection or not. Most of them are losing tickets, but the more of the virus you're exposed to, the greater the chance you have of meeting a virus with a winning ticket.

The more close contact you have with someone, the more virus you're exposed to and the greater the chance that you'll get one of those winning viruses.


This is part of the reason why the overall transmission rates for MERS are low. For a disease to be successful it needs to be able to infect at least one other person before it's killed off by the immune system, or before it kills off the host. On average MERS can only infect ⅗ of a person before its life cycle is over. Yes, I know I just said ⅗ of a person as if thats a real thing that happens, but we're talking averages here. 5 people with the virus will on average cause 3 new infections, and those new infections will between them create about 2 infections, and so on until the outbreak burns itself out.

So the MERS virus should have burned itself out by now. Except, we may be looking at the situation wrong. We may not be dealing with an outbreak of a MERS virus, but of MERS viruses.


MERS viruses plural ? Talk sense man!

To explain this properly, we need to look at a MERS outbreak at the Al-Hasa medical facility. This was a big one. So big that people feared that the worst had happened, that MERS had mutated yet again, making it better at spreading from person to person.


Naturally, researchers were sent strains of MERS viruses sampled during this outbreak. They must have expected to find a brand new super scary, supercharged version of the virus. What they found was not one, but three subtly different MERS viruses. It seems that the Al-Hasa medical facility had the misfortune to be hit with patients from three separate MERS outbreaks at the same time.

This also comes with the realisation that there are lots of different strains of MERS circulating in camel populations. These strains can sporadically evolve the ability to colonise humans, but since they suck at transmitting from human-to-human, they burn themselves out, just in time for another virus to independently make the same jump.


So those folks at the abattoir may not have gotten the infection because the camels didn't have the right strain of MERS to infect humans.

How many people have died from this infection ?

Currently there have been 837 lab confirmed cases, of whom 291 died. That is a 30% fatality rate, which is pretty high. However, these numbers don't take into account the possibility that there are occasionally cases where people get MERS, and don't show any sign of illness at all.


Some of the studies performed also suggest that MERS tends to prey on people who already have other health problems, such as diabetes, heart disease and kidney problems.

It's a brand new disease, and there is still so much we don't know about it. The only reason we notice outbreaks is when people start dying. So we can get a bit myopic, only spotting the cases severe enough to get into hospital. People who only got mild symptoms from MERS tended to chalk it up to a cold, took a few sick days off and didn't bother to go into hospital. Only now, when scientists are actively going out into communities to hunt for the virus do we get to find out about these milder cases of the disease. So the mortality rate for this disease climbs down the more information we get about it.


Will it become a pandemic?

We've seen sufferers travel to other countries outside of the middle east, but they don't actually cause outbreaks. The disease tends to end with them, and doesn't pass on to anybody else.


This turned out to be a real relief, because the Middle East is a massive target for international tourism, especially amongst Muslims who visit Saudi Arabia during the Hajj. But the threat never materialised. MERS stubbornly refused to become a pandemic.

It's spread is SO dependent on infected camels. Without them as a host, these outbreaks would have burned themselves out quickly, and the virus would be extinct. As it stands, the last case of MERS was in July. We are currently in a lull of cases, but odds are that it will re-emerge at some point before the year is out. It may remain a problem for the Middle East for years to come.


This isn't going to be the virus that starts the apocalypse.

So why does MERS frighten people so much?

The best way to understand why there was so much fear surrounding MERS, and any other brand new disease is that they represent the unknown. There is nothing more frightening than the unknown, especially when it starts taking lives.


Nearly everything we discovered about it initially did nothing to alleviate those fears. It was related to SARS, its case fatality rate seemed pretty high, and it was in a region that was a hub of global travel.

The reaction to it since then has been, I don't want to say disappointment, but let's say that a lot of fear boners popped at the outset of this outbreak now flop at half mast.


We've managed to spot this virus before it's fully made the leap into humans. So far, it hasn't made that leap, and there is no guarantee that it will ever make that leap. One day, it could transmit between humans. But not today.

So should I be worried about this ?

I make it my policy not to get panicked over imaginary viruses. The strain of MERS capable of causing a worldwide apocalyptic pandemic simply does not exist. I'll fill my pants when I get evidence it's here, and not a moment before.


But, if you happen to live in the Middle East, then it will probably be around for a while. Will it affect more people than Schistosomiasis, Leishmaniasis or Tuberculosis ? No, it won't. Those disease I've listed are not only scarier, but they affect more people.

Will it significantly increase the Middle Eastern mortality from respiratory diseases ? A little, the Middle East already had the highest incidence of pulmonary disease in the world before MERS appeared. MERS is a drop in the ocean in comparison to the other respiratory diseases ravaging the region.


References/ Further Reading

Summary of probable SARS cases with onset of illness from 1 November 2002 to 31 July 2003


Bats Are Natural Reservoirs of SARS-Like Coronaviruses

Genomic Characterization of Severe Acute Respiratory Syndrome-Related Coronavirus in European Bats and Classification of Coronaviruses Based on Partial RNA-Dependent RNA Polymerase Gene Sequences


Detection of Novel SARS-like and Other Coronaviruses in Bats from Kenya

COMMUNICABLE DISEASE THREATS REPORT-Week 18, 29 April-5 May 2012, The first report of the first outbreak of MERS.


Novel coronavirus infections in Jordan, April 2012: epidemiological findings from a retrospective investigation

Isolation of a Novel Coronavirus from a Man with Pneumonia in Saudi Arabia

Middle East respiratory syndrome coronavirus: quantification of the extent of the epidemic, surveillance biases, and transmissibility


Middle East Respiratory Syndrome Coronavirus Quasispecies That Include Homologues of Human Isolates Revealed through Whole-Genome Analysis and Virus Cultured from Dromedary Camels in Saudi Arabia

Geographic Distribution of MERS Coronavirus among Dromedary Camels, Africa

Transmission and evolution of the Middle East respiratory syndrome coronavirus in Saudi Arabia: a descriptive genomic study - A detailed analysis of the Al-Hasa outbreak


Middle East Respiratory Syndrome Coronavirus Quasispecies That Include Homologues of Human Isolates Revealed through Whole-Genome Analysis and Virus Cultured from Dromedary Camels in Saudi Arabia

Evidence for Camel-to-Human Transmission of MERS Coronavirus

Detection of the Middle East respiratory syndrome coronavirus genome in an air sample originating from a camel barn owned by an infected patient.


Middle East respiratory syndrome coronavirus in dromedary camels: an outbreak investigation

Antibodies against MERS Coronavirus in Dromedary Camels, United Arab Emirates, 2003 and 2013


Middle East respiratory syndrome coronavirus neutralising serum antibodies in dromedary camels: a comparative serological study

Middle East Respiratory Syndrome Coronavirus (MERS-CoV): Announcement of the Coronavirus Study Group


Middle East Respiratory Syndrome Coronavirus in Bats, Saudi Arabia

Epidemiological, demographic, and clinical characteristics of 47 cases of Middle East respiratory syndrome coronavirus disease from Saudi Arabia: a descriptive study


Unanswered questions about the Middle East respiratory syndrome coronavirus (MERS-CoV)

Soaring MERS Cases in Saudi Arabia Raise Alarms


Neglected Tropical Diseases of the Middle East and North Africa: Review of Their Prevalence, Distribution, and Opportunities for Control


Pulmonary diseases may be highest in the Middle East

Image Credits

Colorized transmission electron micrograph of the novel coronavirus that emerged in 2012 National Institute of Allergy and Infectious Diseases (NIAID)


Greater horseshoe bat, Rhinolophus ferrumequinum Schreb. 4/5 natural size by Friedrich Specht

Dromaderies in Tigray Region, Ethiopia

A man mid-sneeze by James Gathany on behalf of the CDC

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