Blame the Camels: MERS-CoV

Spitting, vicious kicking or possibly bucking unprepared tourists from the saddle. These are the ways most people consider camels to be a potential hazard. However, not many are aware that our hump-backed friends may be carrying a virus that has killed over 400 people in the last 3 years. The virus in question is called Middle Eastern respiratory system coronavirus (or MERS-CoV if you don’t fancy that mouthful) and has spread throughout the Middle East and beyond since the first confirmed case in Saudi Arabia in 2012.

(Before I come on to talking about the virus it should be remembered that camels definitely do spit, as the cameraman found out at the end of the following video…)

MERS-CoV is, as the catchy name suggests, a coronavirus. This distinctively crown-shaped (corona meaning crown or halo in Latin) family of viruses is also home to the severe acute respiratory syndrome coronavirus (SARS-CoV). As you may have guessed, this member of the family was responsible for the SARS outbreak that terrified the world in 2003, infecting 8000 and killing over 800. Both viruses kill their victims by causing severe breathing difficulties and kidney failure.

Coronaviruses_004_lores
Not exactly on a par with the crown jewels but there’s definitely some kind of halo there

Naturally, when MERS was first described in 2012, epidemiologists the world over were concerned that a new SARS was about to sweep the world. Although similar rates of infection have not yet been observed, MERS persists in Saudi Arabia and the surrounding countries. The World Health Organisation (WHO) reported that between 3rd – 10th March 2015 there were 15 new cases of MERS-CoV infection, including 5 deaths.

To fully understand the risks posed by this virus, it is first important to understand its origins. SARS is thought to have been transmitted into humans from bats, but where did MERS come from? Scientists combed through various local species to track down the elusive origin, eventually finding evidence of the virus in local groups of camels (fun fact: a commonly used collective noun for a group of camels is a ‘caravan of camels’)

In the last year, further research has firmly established the spitting, kicking animals as a reservoir of the disease (find a simple summary of this paper here), and a there is evidence that the MERS-CoV virus may have been circulating in the camel population of Saudi Arabia since 1992.

In case you entertained any doubts that we should blame the camels, in June 2014, the New England Journal of Medicine reported the sorry tale of a 44 year old Saudi man who died of MERS-CoV after attempting to apply medicine to the nose of one of his sick camels. When the virus that killed the man and the virus present in the sick camels were analysed they were found to be identical.

07._Camel_Profile,_near_Silverton,_NSW,_07.07.2007
Don’t get lured in by these majestic shots: this guy could give you MERS

So it’s pretty clear that camels have played – and continue to play –  an important role in the spread of the virus. However, one of the hallmark features of a pandemic is the ability of the disease to be transmitted not just from animal to human but also from human to human.

An outbreak in a hospital in Saudi Arabia between April and May 2013 provides ominous evidence that MERS is able to spread  effectively between people. Of the 23 cases reported during this outbreak, 21 had been acquired by person-to- person transmission in the hospital. Clearly the patients in an intensive care unit in a hospital are not representative of the public as a whole, but this does demonstrate that the virus is capable of making the jump between people.

MERS appears capable of spreading only by direct contact with an infected individual, so in this respect its ability to spread is limited. Unless, for example, the country in which the majority of infections have occurred hosts an event in which an infected individual could come into direct contact with over two million people. Good job that’s completely unrealistic. Oh wait…

Al-Haram_mosque_-_Flickr_-_Al_Jazeera_English
For a virus looking to infect as many people as possible, situations don’t get much better than this

The Hajj pilgrimage, in which millions of Muslims from all over the world congregate at various holy sites in Saudi Arabia, surely has catastrophe written all over it. However, the Saudi authorities have treated the threat extremely seriously and through measures such as airport isolation rooms and health screening questionnaires (more details of these preventative measures are in this Guardian article) the 2013 and 2014 pilgrimages were prevented from becoming breeding grounds for the virus.

The potential for MERS to cause a SARS-like pandemic in the near future is hard to predict, however the virus has been shown to be capable of human-to-human transmission and continues to persist in the Arabian peninsular. MERS has an unusually high case fatality rate (the percentage of infected individuals who die from the disease) for a respiratory virus – around 30% on average – so if a pandemic did kick off it could cause a significant death toll.

The SARS outbreak, although a horrific ordeal for many, did teach the international health community a number of important lessons (summarised by the WHO here) about dealing with a pandemic threat. This knowledge will make it increasingly difficult for an emerging virus – especially one that is so similar to SARS-CoV, like MERS-CoV – to make the leap into a full-blown pandemic.

For now though, watch out for those camels.

Pandemic potential = 7/10

Photo credits:

“07. Camel Profile, near Silverton, NSW, 07.07.2007” by Jjron – Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons – http://commons.wikimedia.org/wiki/File:07._Camel_Profile,_near_Silverton,_NSW,_07.07.2007.jpg#/media/File:07._Camel_Profile,_near_Silverton,_NSW,_07.07.2007.jpg

“Al-Haram mosque – Flickr – Al Jazeera English” by Al Jazeera English – Al-Haram mosque. Licensed under CC BY-SA 2.0 via Wikimedia Commons – http://commons.wikimedia.org/wiki/File:Al-Haram_mosque_-_Flickr_-_Al_Jazeera_English.jpg#/media/File:Al-Haram_mosque_-_Flickr_-_Al_Jazeera_English.jpg

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