Middle East Respiratory Syndrome (MERS)

Alternative names

Middle East Respiratory Syndrome Coronavirus; MERS-CoV; Novel coronavirus; nCoV


Middle East Respiratory Syndrome (MERS) is a severe respiratory illness. It causes fever, coughing, and shortness of breath. About 30% of people who have gotten this illness have died. Some people only have mild symptoms.

MERS is caused by the Middle East Respiratory Syndrome Coronavirus (MERS-CoV). It was first reported in Saudi Arabia in 2012. MERS has infected people in:

  • Saudi Arabia
  • United Arab Emirates (UAE)
  • Qatar
  • Oman
  • Jordan
  • Kuwait
  • Yemen

MERS has also been reported in:

  • Egypt
  • United Kingdom
  • France
  • Italy
  • Greece
  • Malaysia
  • Philippines
  • Tunisia
  • Turkey
  • United States

Most of these cases are from people who traveled to the Middle Eastern countries listed above.

To date, there have only been two cases of MERS in the U.S. They were in people traveling to the U.S. from Saudi Arabia. The virus poses a very low risk to people in the U.S.

How MERS spreads

No one knows exactly where the MERS virus comes from. It has also been found in camels and in one bat. While it is believed to come from animals, that is still unclear.

The virus can spread between people in close contact. This includes health care workers who care for people with MERS.

The incubation period of this virus is not precisely known. This is the amount of time between when a person is exposed to the virus and when symptoms occur. In the first cases, the average incubation period seemed to be 5 days, but there are cases that occurred up to 14 days after exposure.

MERS symptoms

The most common symptoms have included fever, chills, and cough. Less common symptoms include coughing up blood, diarrhea, and vomiting. However, these symptoms can also occur in a number of other conditions.

All patients with MERS had an abnormal chest X-ray.

Right now, there is no vaccine for MERS and no treatment.

Steps to help prevent MERS

If you plan to travel to one of the countries where MERS is present, the CDC recommends taking the following steps to prevent illness.

  • Wash your hands often with soap and water for 20 seconds. Help young children do the same. If soap and water are not available, use an alcohol-based hand sanitizer.
  • Cover your nose and mouth with a tissue when you cough or sneeze then throw the tissue in the trash.
  • Avoid touching your eyes, nose, and mouth with unwashed hands.
  • Avoid close contact, such as kissing, sharing cups, or sharing eating utensils, with sick people.
  • Clean and disinfect frequently touched surfaces, such as toys and doorknobs.

Last year, the Ministry of Health of Saudi Arabia recommended that certain people consider postponing their plans to travel to Mecca, Saudi Arabia. These include:

  • Older adults (65 years of age and older)
  • People with chronic health conditions such as heart disease, asthma, or diabetes
  • People with an immune deficiency (congenital or acquired)
  • People with cancer
  • People with a terminal illness
  • Pregnant women
  • Children, 12 years of age and younger

For more information about MERS, go to the CDC website: http://www.cdc.gov/coronavirus/mers/faq.html.


Middle East Respiratory Syndrome (MERS): frequently asked questions and answers. Centers for Disease Control and Prevention (CDC) Web site. http://www.cdc.gov/coronavirus/mers/faq.html. Accessed May 5, 2014.

Coronavirus infections. World Health Organization (WHO) Web site. http://www.who.int/csr/disease/coronavirus_infections/en/. Accessed May 12, 2014.

Review date:
October 5, 2014
Reviewed by:
Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.
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