Emergencies preparedness, response

Frequently asked questions on Middle East respiratory syndrome coronavirus (MERS‐CoV)


15 May 2017

1. What is Middle East respiratory syndrome (MERS)?

Middle East respiratory syndrome (MERS) is a viral respiratory illness caused by a coronavirus (Middle East respiratory syndrome coronavirus, or MERS‐CoV) that was first identified in Saudi Arabia in 2012. Coronaviruses are a large family of viruses that can cause diseases in humans, ranging from the common cold to Severe Acute Respiratory Syndrome (SARS).

2. Where have cases of MERS been identified?

Since 2012, MERS has been reported in 27 countries including Algeria, Austria, Bahrain, China, Egypt, France, Germany, Greece, Islamic Republic of Iran, Italy, Jordan, Kuwait, Lebanon, Malaysia, the Netherlands, Oman, Philippines, Qatar, Republic of Korea, Kingdom of Saudi Arabia, Thailand, Tunisia, Turkey, United Arab Emirates, United Kingdom, United States, and Yemen. Approximately 80% of human cases reported by the Kingdom of Saudi Arabia. Cases identified outside the Middle East are people who were infected in the Middle East and travelled to areas outside the Middle East. On rare occasions, small outbreaks have occurred in areas outside the Middle East.

3. How do people get infected with the MERS virus?

The MERS virus is transmitted primarily from animals to people, but transmission from people to people is also possible.

From animals to people

MERS-CoV is a zoonotic virus, meaning it is transmitted between animals and people. Scientific evidence suggests that people are infected through direct or indirect contact with infected dromedary camels. The MERS virus (written as MERS-CoV) has been identified in dromedary camels in several countries, including Egypt, Oman, Qatar and Saudi Arabia. There is further evidence suggesting the MERS-CoV is widespread in dromedary camels in the Middle East, Africa and parts of South Asia. It is possible that other animal reservoirs exist, however animals including goats, cows, sheep, water buffalo, swine, and wild birds have been tested for MERS-CoV and the virus has not been found.

Between people

MERS-CoV does not pass easily between people unless there is close contact, such as the provision of clinical care to an infected patient without strict hygiene measures. Transmission between people has been limited to-date, and has been identified among family members, patients, and health care workers. While, the majority of reported MERS cases to date have occurred in health care settings, thus far, no sustained human to human transmission has been documented anywhere in the world.

4. What are the symptoms of MERS? How severe is it?

A typical case of MERS includes fever, cough, and/or shortness of breath. Pneumonia is common, however some people infected with the MERS virus have been reported to be asymptomatic. Gastrointestinal symptoms, including diarrhoea, have also been reported. Severe cases of MERS can include respiratory failure that requires mechanical ventilation and support in an intensive-care unit.

Some patients have had organ failure, especially of the kidneys, or septic shock. The virus appears to cause more severe disease in people with weakened immune systems, older people, and people with chronic diseases as renal disease, diabetes, cancer, and chronic lung disease. The mortality rate for people with the MERS virus is approximately 35% – this may be an overestimate however, as mild cases may be missed by existing surveillance systems.

5. Is there a vaccine for MERS‐CoV? What is the treatment?

No vaccine or specific treatment for MERS is currently available. Treatment is supportive and based on a person’s clinical condition.

6. Can someone be infected with MERS-CoV and not be ill?

Yes, infection with MERS-CoV can be asymptomatic. Infected people with no symptoms have been identified because they were tested for MERS-CoV during investigations among contacts of people known to be infected with MERS-CoV.

7. Is it easy to detect people who are infected with MERS-CoV?

It is not always possible to identify people infected with the MERS virus because early symptoms of the disease are non-specific and are often mistaken for other respiratory diseases. For this reason, all health care facilities should have standard infection prevention and control practices in place. It is also important to investigate the travel history of people with respiratory infection to determine if they have recently visited countries with active MERS-CoV circulation or have had contact with dromedary camels.

8. Is MERS contagious?

Yes, but human to human transmission has been limited. The virus does not seem to pass easily from person to person unless there is close contact, such as occurs when providing unprotected care for a patient. There have been clusters of cases in health care facilities, where human-to-human transmission appears to be more efficient, especially when infection prevention and control practices are inadequate. The largest health care associated outbreaks have occurred in Saudi Arabia and the Republic of Korea.

9. What is contact tracing and why is it important?

Those in close contact with someone who has MERS are at higher risk of infection, and of potentially infecting others if they begin to show symptoms. Closely watching such persons for 14 days from the last day of exposure to a confirmed case will help that person to get care and treatment and will prevent further transmission of the virus to others. This monitoring process is called contact tracing, which can be broken down into three basic steps:

  • Contact identification: Once a case is confirmed, contacts are identified by asking about the activities of the case and the activities and roles of the people around the case since onset of illness. Contacts can be family members or anyone who has been in contact with the case, for example, people encountered at work, social events or in health care facilities.
  • Contact listing: All persons considered to have contact with the confirmed case should be listed as contacts. Efforts should be made to identify every listed contact and inform them of their contact status, what it means, the actions that will follow, and the importance of receiving early care if they develop symptoms. The contact should also be provided with information about prevention of the disease. In some cases, quarantine or isolation is required for high risk contacts, either at home, or in hospital.
  • Contact follow-up: Follow-up all listed contacts daily for 14 days from the last time they were in contact with the confirmed MERS patient for the development of signs and symptoms and for testing for MERS-CoV.

10. What should a person do if she/he has contact with a person who has MERS?

If you have had close contact with someone infected with MERS-CoV within the last 14 days without using the recommended infection control precautions, you should contact a healthcare provider for an evaluation.

11. What is the source of the MERS virus?

MERS-CoV has been found in dromedary camels in several countries, including in Egypt, Oman, Qatar, and Saudi Arabia. It is possible that other animal reservoirs exist. However, animals including goats, cows, sheep, water buffalo, swine, and wild birds have been tested for MERS-CoV and the virus has not been found. These studies support the premise that dromedary camels are the likely source of infection in humans, but studies and investigations have not yet identified how humans are infected with the MERS virus.

The origins of the virus are not fully understood but, according to the analysis of different virus genomes, it is believed that MERS-CoV may have originated in bats and was transmitted to camels in the distance past.

12. Should people avoid contact with camels or camel products? Is it safe to visit farms, markets, or camel fairs?

As a general precaution, anyone visiting farms, markets, barns, or other places where animals are present should practice general hygiene measures. These include regular hand-washing before and after touching animals, and avoiding contact with sick animals.

The consumption of raw or undercooked animal products, including milk and meat, carries a high risk of infection from a variety of organisms. Animal products processed appropriately through cooking or pasteurization are safe for consumption, but should also be handled with care to avoid cross-contamination with uncooked foods. Camel meat and camel milk are nutritious products that can be consumed after pasteurization, cooking, or other heat treatments.

Until more is understood about MERS-CoV, 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. Especially in the Middle East, this group of people should avoid contact with dromedary camels, consuming raw camel milk or camel urine, as well as eating meat that has not been properly cooked.

Camel farm and slaughterhouse workers should practice good personal hygiene, including frequent hand washing, facial protection, and protective clothing (which should be removed after work and washed daily). Workers should also avoid exposing family members to soiled work clothing, shoes, or other items that may have come into contact with camels or camel excretions. Sick animals should never be slaughtered for consumption. People should avoid direct contact with any animal that has been confirmed positive for MERS-CoV infection.

13. Are health care workers at risk from MERS‐CoV?

Yes. Transmission of MERS-CoV has occurred in health care facilities in several countries, most notably in Saudi Arabia, United Arab Emirates and the Republic of Korea. It is not always possible to identify patients infected with MERS-CoV early or without testing because symptoms may be mild and other clinical features may be non-specific. For this reason, it is important that health care workers apply standard precautions consistently while caring for all patients.

Droplet precautions should be added to standard precautions when providing care to all patients with symptoms of acute respiratory infection. Contact precautions and eye protection should be added when caring for suspected or confirmed cases of MERS. Airborne precautions should be applied when performing aerosol‐generating procedures.

14. How is WHO responding to MERS?

WHO is working with academic and public health professionals to gather and share scientific evidence to better understand the virus and the disease it causes, and to determine outbreak response priorities, treatment strategies, and clinical management approaches. WHO is also working with affected countries and international partners, such as FAO and OIE, to coordinate the global health response, including providing updated information, conducting risk assessments and coordinated investigations with national authorities, convening scientific meetings, and developing technical guidance and training on surveillance, laboratory testing, infection prevention and control, and clinical management.

WHO is also coordinating with the affected countries and international health partners to identify the current knowledge gaps on transmission risk factors as well as developing medical countermeasures. MERS-CoV is one of the high threat pathogens included in the WHO’s Research & Development Blue Print which provides a road map for research and development of diagnostic, preventive and therapeutic products for prevention, early detection and response to these threats caused by a list of 11 high prioritized pathogens.

The Director‐General convened an Emergency Committee under the International Health Regulations (2005) to advise her as to whether this event constitutes a Public Health Emergency of International Concern (PHEIC) and on public health measures that should be taken. Information on the deliberations of the Committee can be found here:

15. What does WHO recommend?

For countries

WHO encourages all Member States to enhance their surveillance for severe acute respiratory infections (SARI) and to carefully review any unusual patterns of SARI or cases of pneumonia. Cases should be isolated as soon as possible, and close contacts should be identified and monitored. WHO urges Member States to notify or verify to WHO any probable or confirmed case of MERS. WHO also urges Member States to stay abreast of the evolution of the disease and modify their interventions according to current risk. WHO guidance is available at the following links.

For health care workers

Infection prevention and control measures are critical to prevent the possible spread of MERS-CoV in health care facilities. Health care facilities that provide care for suspected or confirmed MERS patients should take appropriate measure to decrease the risk of transmission of the virus from an infected patient to other patients, health care workers, and visitors. Health care workers should be educated, trained, and refreshed with skills on standard infection prevention and control.

16. General travel advice

Given the current pattern of transmission of the disease WHO does not recommend travel or trade restrictions with regard to MERS-CoV. However, national authorities may take precautions aimed at raising awareness of MERS and its symptoms among travellers to and from affected areas, based on their own local risk assessment.

As required by the International Health Regulations (IHR 2005), countries should ensure that routine measures are in place for assessing ill travellers detected on board means of transport (such as planes and ships) and at points of entry, as well as measures for safe transportation of symptomatic travellers to hospitals or designated facilities for clinical assessment and treatment. If a sick traveller is on board a plane, a passenger locator form can be used. This form is useful for collecting contact information for passengers, which can be used for follow-up if necessary.

17. Travel to the Middle East

WHO does not advise special screening at points of entry, nor does it currently recommend the application of any travel or trade restrictions. Recommended actions include:

1. Advise travelers with pre-existing medical conditions to avoid contact with dromedary camels in the Middle East, and in other countries where infected dromedaries have been identified.