Middle East Respiratory Syndrome (MERS)

Middle East Respiratory Syndrome (MERS) is an infectious disease of the respiratory tract caused by the MERS coronavirus (MERS-CoV), which was first discovered in 2012.

The virus causes disease in both humans and dromedary (single-humped) camels and can be transmitted between humans and animals. In dromedary camels, the symptoms of infection are very mild.

To date, most infections with the MERS virus have occurred in countries on the Arabian Peninsula. Most outbreaks occurred in Saudi Arabia. To date, any MERS infections occurring outside of the Arabian Peninsula have been associated with a prior stay in this region or close contact with other people with a MERS-CoV infection.

Unlike the related coronaviruses SARS-CoV and SARS-CoV-2 – the pathogens that cause SARS and COVID-19 – the World Health Organization (WHO) does not regard MERS-CoV as a threat to global health. This is because MERS has a low level of human-to-human transmissibility.

People infected with the MERS coronavirus sometimes have no symptoms. This is known as an asymptomatic infection.

If symptoms do develop, they usually occur between one and three weeks after infection.

The majority of people who contract MERS initially have flu-like symptoms. These include:

• high temperature
• chills
• aching limbs
• cough
• shortness of breath

Gastrointestinal symptoms, such as diarrhea, nausea and abdominal pain sometimes also occur.

Over the course of the illness, people often develop pneumonia, acute respiratory distress syndrome and/or kidney failure.

MERS occurs as a result of an infection with the MERS-CoV coronavirus. Infections are primarily caused by close contact with infected dromedary camels. Diseases like this that can be transmitted between humans and animals are known as zoonotic diseases.

Person-to-person transmission is also possible with MERS but rarely occurs in residential settings. Most cases transmitted this way occur in healthcare settings, especially in hospitals.

These occasionally occur as part of super-spreader events, in which one infected person infects many other people. The precise way in which MERS spreads remains unknown. It is suspected that smear infection (infection by touch) and droplet (airborne) infection may play a role.

People over the age of 60 in particular have an increased risk of developing a severe MERS infection.

Other risk factors are chronic health conditions, especially diabetes, high blood pressure, cardiovascular diseases and kidney diseases.

To date, almost 2,600 MERS infections have been documented worldwide, with the majority occurring in the countries on the Arabian Peninsula – in particular Saudi Arabia. Almost 900 people have died from MERS or from complications of the disease.

If someone has never been to this region and has no contact with dromedary camels, they have a very low risk of contracting MERS.

There have only ever been three documented cases of MERS in Germany. All three of the people involved had previously traveled to the Arabian Peninsula and had contracted the infection there. None of them spread the infection to any other individuals in Germany.

MERS can have mild to severe symptoms or none at all. Up to 50 percent of people diagnosed with a MERS infection have a moderate to severe form of the infection. The severity of the infection generally increases with age. Older people are also at an increased risk of dying from MERS.

MERS infections frequently lead to complications such as:

• pneumonia
• acute respiratory distress syndrome (ARDS)
• renal failure

Almost all people who contract MERS require hospital treatment. Many of them also need mechanical ventilation. Around one third of patients die from the effects and complications of MERS.

There are as yet no approved vaccines to prevent a MERS infection. This makes the precautionary measures described below all the more important when seeking to protect oneself from the disease.

Avoid contact with dromedary camels

MERS is frequently transmitted from dromedary camels to humans. The World Health Organization (WHO) therefore recommends that people, in particular those at a higher risk of infection, avoid contact with dromedary camels and avoid consuming any raw products from dromedary camels, such as milk or meat.

Take care when visiting the Arabian Peninsula

The WHO generally recommends that people who travel to the Arabian Peninsula or surrounding regions observe good hand hygiene practice and avoid contact with people who have a respiratory disease.

Limit contact and observe good hygiene practice

To prevent a person-to-person infection with MERS-CoV, people with a confirmed infection or a suspected infection should self-isolate at home.

Healthcare professionals should be rigorous about hygiene and wear personal protective equipment, such as gloves, goggles and an FFP2 mask when treating patients with MERS.

If a person suspects that they have contracted MERS – for example, if they develop a lung infection following a trip to the Arabian Peninsula, it is recommended that they get tested to confirm an infection.

Their doctor will generally send samples from the lower respiratory tract to a lab for analysis. A laboratory PCR test can detect the genetic material of MERS coronaviruses in the samples.

No medications exist for the targeted treatment of MERS. Specific medications to target MERS are still being developed and tested. 

Current treatment seeks to relieve symptoms and to support patients as effectively as possible – for example, by means of oxygen therapy. Mechanical ventilation is required in very severe cases.