What is Middle East Respiratory Syndrome (MERS)?

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Following the COVID-19 pandemic, you may wonder if there are other coronaviruses that you should be concerned about and that you need to protect yourself from. A coronavirus that is frequently compared to the virus that causes COVID-19 is the coronavirus associated with Middle East respiratory syndrome (MERS). This article will explore MERS by discussing how the virus causes the disease, the symptoms an affected individual may present with, and the diagnosis process. Commonly asked questions, such as who is at risk of MERS and when you should seek medical help, will also be answered.


Middle East respiratory syndrome (MERS) is a respiratory disease caused by the Middle East respiratory syndrome Coronavirus (MERS-CoV), which was first identified in humans in Saudi Arabia and Jordan in 2012, hence the name ‘Middle East’.1 The condition is rare but very severe, with initial symptoms of fever and cough potentially progressing into breathing difficulties, pneumonia, and kidney failure.

MERS is a zoonotic virus, meaning that it is transmitted from animals to humans. It is thought that MERS is passed to humans from infected camels, but can also spread between people who have been in close contact. Despite a niche route of transmission (as camels do not populate every country), MERS infections lead to high mortality in humans. There are still few effective therapies that are able to treat the complicated, viral condition.1

Disease mechanisms of MERS

You now have an understanding of where the virus comes from and how it is usually transmitted. However, we have not discussed how MERS-CoV causes the disease to arise in humans. This is important, as improving our understanding of the disease mechanism can help to improve therapies and save lives. This can also help to identify similarities between MERS and novel coronaviruses, for which treatments may be shared.

MERS is a respiratory condition. Typically, the virus is spread through small droplets, which could be in the form of a cough or a sneeze of an infected person (or the saliva of a dromedary camel). These small droplets are often inhaled by someone who is within close proximity to the infected person, allowing the virus to get inside the nose, mouth and lungs of a new patient.2

The main evolutionary aim of a virus is to replicate and reproduce. Yet, the virus itself does not possess the essential machinery for self-replication. In contrast, human cells have this machinery, giving them the ability to produce proteins and initiate DNA replication. Therefore, a virus must enter a human cell and hijack its machinery in order to replicate.3

Picture the virus within a water droplet inside of the lungs, waiting to enter a human cell that forms the lining of the lungs. A spike protein on the outer surface of the virus binds to a protein on the surface of the lung cell, known as an epithelial cell. Once inside the lung cell, it rapidly replicates numerous times using the machinery of the host cell. Once a certain limit has been reached, the cell bursts and expels the virus. This allows the virus to continue spreading within the body. This process repeats in many lung cells, which are each destroyed as viruses are released post-replication.3,4

The immune system is activated with the aim of destroying any virus within the body, as well as destroying any infected cells that are damaging the lungs. It is possible for the virus to spread inside the body through the bloodstream, affecting the kidneys, the intestines, and the liver. This leads to a range of life-threatening symptoms.4

Signs and symptoms of MERS

It is possible to be positive for MERS-CoV up to an average of 5 days before symptoms begin to present. General symptoms of MERS include a fever of 38℃, chills, fatigue, body aches, and loss of appetite. More specific symptoms include: 

  • A runny nose
  • A sore throat
  • A cough
  • Shortness of breath
  • Coughing up blood
  • Chest pain
  • Nausea
  • Diarrhoea
  • Abdominal discomfort

Diagnosis of MERS

If your doctor suspects that you may have MERS, you are likely to receive a chest X-ray, blood tests, and a respiratory swab test. Your doctor will take your medical history and enquire about your travelling history, as you are more likely to have contracted the infection if you have recently visited the Middle East. Additionally, your doctor will assess your condition and treat you depending on how severe your symptoms are, as well as how likely you are to develop complications.

Many symptoms of MERS can occur in a lot of other viral illnesses, so it is important for your doctor to determine whether you are likely to have been infected by MERS-CoV or by a different virus altogether. The identity of the virus can be confirmed through a serology test, which tests if you have formed antibodies (proteins that are important for mounting an immune response) against MERS-CoV.5


Who is at risk of MERS?

If you have recently travelled to the Middle East, have been in contact with a known sick person or an infected dromedary (Arabian) camel, or work in a healthcare setting, you will be at higher risk of contracting MERS-CoV.

People with pre-existing comorbidities are at a higher risk of complications if they become affected by MERS. You have a higher chance of experiencing a more severe infection if the following applies to you:6

When should you see a doctor?

If you are experiencing any of the symptoms listed above, particularly if you have previously been diagnosed with one of the aforementioned conditions or have recently travelled to the Middle East, it is a good idea to seek medical advice.

If at any point it becomes very difficult to breathe, call 999 for emergency care.

Can MERS be prevented?

The best way to prevent the spread of any virus is to wash your hands frequently (with soap and water) for at least twenty seconds. If you think that you may have been exposed to MERS (either through an encounter with a sick person or an infected camel), take care to isolate yourself, take extra care to wash your hands, cover your mouth, and sanitise surfaces around you frequently.

How common is MERS?

According to the World Health Organisation (WHO), 27 countries have reported cases of MERS since 2012, with 858 deaths being attributed to disease-related complications. MERS appears to be particularly contagious only when people have come into close contact with each other, meaning it does not spread as quickly as COVID-19


Middle East respiratory syndrome (MERS) is caused by the MERS Coronavirus, which is a zoonotic virus that was first detected in humans in Saudi Arabia. It is not particularly common or contagious but it can be fatal. If you have recently travelled to the Middle East, or have been in contact with a sick person or an infected camel, it is important to observe your condition and prioritise your hygiene. If you are concerned or experience any of the symptoms listed above, it is essential that you seek medical help, particularly if you have a pre-existing medical condition that can increase your risk of developing disease-related complications.


  1. Zaki AM, van Boheemen S, Bestebroer TM, Osterhaus AD, Fouchier RA. Isolation of a novel coronavirus from a man with pneumonia in Saudi Arabia. N Engl J Med. 2012;367:1814–1820 https://pubmed.ncbi.nlm.nih.gov/23075143/ 
  2. Niazi S, Groth R, Spann K, Johnson GR. The role of respiratory droplet physicochemistry in limiting and promoting the airborne transmission of human Coronaviruses: A critical review. Environmental Pollution. 2021;276:115767. doi:10.1016/j.envpol.2020.115767 https://pubmed.ncbi.nlm.nih.gov/33243541/ 
  3. Singh S. Middle East Respiratory Syndrome Virus Pathogenesis. Seminars in Respiratory and Critical Care Medicine. 2016 Aug 3;37(04):572–7. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7171719/ 
  4. Du L, Yang Y, Zhou Y, Lu L, Li F, Jiang S. MERS-CoV spike protein: a key target for antivirals. Expert Opinion on Therapeutic Targets. 2016 Dec 21;21(2):131–43. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5457961/ 
  5. Al Johani S, Hajeer AH. MERS-CoV diagnosis: An update. Journal of Infection and Public Health [Internet]. 2016 May 1 [cited 2020 Apr 11];9(3):216–9. Available from: https://www.sciencedirect.com/science/article/pii/S1876034116300223 
  6. Ng DL, Al Hosani F, Keating MK. Clinicopathologic, immunohistochemical, and ultrastructural findings of a fatal case of Middle East respiratory syndrome coronavirus infection in the United Arab Emirates, April 2014. Am J Pathol. 2016;186:652–658. https://pubmed.ncbi.nlm.nih.gov/26857507/ 

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This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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