Middle East respiratory syndrome coronavirus (MERS-CoV) Factsheet

What is MERS-CoV?
MERS-CoV is a zoonotic virus (i.e. it can be transmitted from animals to humans). Dromedary camels are believed to be the animal reservoir for the virus. This virus was first identified in 2012 in a patient from the Middle East who died from a severe respiratory infection. The origins of the virus are not fully understood but, according to the analysis of different virus genomes, it is believed that it originated in bats and was transmitted to dromedary camels sometime in the distant past.

The virus appears to be circulating throughout the Arabian Peninsula. The majority of human cases (approximately 80%) have been reported from Saudi Arabia. Most of the infections outside of the Middle East are believed to have been acquired in the Middle East, and then exported outside the region, with limited further transmission in countries with exported cases.

How is it transmitted?
The majority of human cases reported have been due to person-to-person transmission in healthcare settings (see below). However, the virus does not appear to pass easily from person to person unless there is close contact. Outside of the healthcare setting there has been limited person to person transmission.

The majority of human cases infected outside of healthcare settings have had links to dromedary camels. The route of transmission from infected dromedary camels to humans is not fully understood. Dromedary camels infected with MERS-CoV may not show any signs of infection. However, infected animals may shed the virus through nasal and eye discharge, faeces, and potentially in their milk and urine. The virus may also be found in the raw organs and meat of infected animals.

What are the symptoms of MERS-CoV infection?
MERS-CoV infection can vary in severity from mild respiratory symptoms to severe respiratory disease and other life-threatening complications. It can also be asymptomatic (i.e. not have any symptoms).

A typical presentation of MERS-CoV disease is fever, cough and shortness of breath. Pneumonia may be present. Gastrointestinal symptoms, including diarrhoea, have also been reported. Severe illness can cause respiratory failure that requires mechanical ventilation and support in an intensive care unit. Approximately 35% of reported patients with MERS-CoV have died.

What is the treatment?
No vaccine or specific treatment is currently available. Treatment is supportive and based on the patient’s clinical condition.

Who is most at risk?
People in close contact with dromedary camels (e.g. farmers, abattoir workers, shepherds, dromedary camel owners) and health workers caring for MERS-CoV patients are believed to be at the highest risk of infection.

People with diabetes, renal failure, chronic lung disease, and immunocompromised persons are considered to be at high risk of severe disease from MERS-CoV infection. Healthy adults tend to have mild infection.

How many people have been infected?
As of 16 May 2017, WHO has been notified of 1,952 laboratory-confirmed cases of infection with MERS-CoV and at least 693 deaths related to MERS-CoV. As these figures will change, please refer to the WHO website for the latest figures.

What countries have been affected?
As of May 2017, 27 countries had reported cases, including the following countries:

• Middle East: Bahrain, Egypt, Iran, Jordan, Kuwait, Lebanon, Oman, Qatar, Kingdom of Saudi Arabia (KSA), United Arab Emirates (UAE) and Yemen
• Africa: Algeria and Tunisia
• Europe: Austria, France, Germany, Greece, Italy, the Netherlands, Turkey and the United Kingdom
• Asia: China, the Republic of Korea, Malaysia, Philippines and Thailand
• North America: the United States of America (USA)

For an up-to-date list of countries who have reported cases of MERS-CoV, see the WHO MERS-CoV website.

Might we get a case in Ireland?
Yes, it is possible that we might have an imported case of MERS-CoV in Ireland in a person who was exposed to the virus through contact with dromedary camels or in a healthcare setting in the Middle East. WHO expects that additional cases of MERS-CoV infection will be reported from the Middle East, and that cases will continue to be exported to other countries. If an imported case is diagnosed in Ireland, there are guidelines in place to reduce the risk of further spread.

Transmission in health care settings
Transmission of the virus from person to person has occurred in healthcare facilities in several countries. Transmission has occurred from patients to healthcare providers and between patients.

Large nosocomial outbreaks have been reported in Riyadh, Saudi Arabia, Amman in Jordan, and in the Republic of Korea. Smaller nosocomial outbreaks have been reported in several Saudi Arabia cities.

The outbreak in the Republic of Korea in 2015 was the largest outbreak reported outside of the Middle East. A single case was imported from the Middle East with subsequent person-to-person transmission, much of which occurred in healthcare settings. This outbreak involved a total of 186 MERS-CoV cases in more than 17 health care settings.

Person-to-person transmission in healthcare settings has been associated with delays in recognising possible patients, slow triage of suspected patients, delays in implementing infection, prevention and control (IPC) measures, and inadequate IPC measures. A number of studies of the outbreak in the Republic of Korea, have suggested that the persistence of the virus on surfaces could have contributed to some of the transmission in hospitals.

Infection prevention and control advice is available in the guidance section.

Travel advice
If you are thinking of travelling to the Middle East or have recently returned please see the travel advice section.

Last updated: 26 May 2017