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Middle East Respiratory Syndrome (MERS)

Photo: MERS-CoV particles as seen by negative stain electron microscopy. Virions contain characteristic club-like projections emanating from the viral membrane.There have been no MERS cases in the United States since May 2014. The risk of MERS to the general public in this country remains very low. CDC and other public health partners continue to closely monitor the MERS situation.

Since MERS first emerged in the Arabian Peninsula in 2012, CDC has been working with global partners to better understand the nature of the virus, including how it affects people, and how it spreads. We recognize the potential for MERS-CoV to spread further and cause more cases in the United States and globally, and we are taking actions in preparation. Learn more.

MERS in the U.S.

MERS in Republic of Korea

Since May 2015, the Republic of Korea has been investigating an outbreak of MERS. It is the largest known outbreak of MERS outside the Arabian Peninsula.

CDC does not recommend that Americans change their travel plans to the Republic of Korea or other countries because of MERS. More

Only two patients in the U.S. have ever tested positive for MERS-CoV infection—both in May 2014—while more than 500 people have tested negative. In May 2014, CDC confirmed two cases of MERS in the United States – one in Indiana, the other in Florida. Both cases were among healthcare providers who lived and worked in Saudi Arabia. Both traveled to the U.S. from Saudi Arabia, where they are believed to have been infected. Both were hospitalized in the U.S. and later discharged after fully recovering.

Understanding the Virus

Middle East Respiratory Syndrome (MERS) is a viral respiratory illness that is new to humans. It was first reported in Saudi Arabia in 2012. The virus that causes MERS is called Middle East Respiratory Syndrome Coronavirus (MERS-CoV). Coronaviruses are common viruses that most people get some time in their life. Human coronaviruses usually cause mild to moderate upper-respiratory tract illnesses. However, MERS-CoV is different from any other coronavirus previously found in people.

MERS-CoV likely came from an animal source in the Arabian Peninsula. Researchers have found MERS-CoV in camels from several countries . We don’t know whether camels are the source of the virus. Studies continue to provide evidence that camel infections may play a role in human infection with MERS-CoV. However, more information is needed.

MERS Symptoms

Some infected people had mild symptoms or no symptoms at all, but most people infected with MERS-CoV developed severe respiratory illness. They had fever, cough and shortness of breath. Others reported having gastrointestinal symptoms, like diarrhea and nausea/vomiting, and kidney failure. MERS can even be deadly. Many people have died.

How MERS Spreads

MERS-CoV is thought to spread from and infected person to others though respiratory secretions, such as coughing. In other countries, the virus has spread from person to person through close contact, such as caring for or living with an infected person.

Protect yourself from Respiratory Illnesses

There is currently no vaccine to prevent MERS-CoV infection. CDC routinely advises Americans to help protect themselves from respiratory illnesses by

  • washing hands often,
  • avoiding close contact with people who are sick,
  • avoiding touching their eyes, nose and mouth with unwashed hands, and
  • disinfecting frequently touched surfaces.

MERS and Travel

CDC does not recommend that anyone change their travel plans because of MERS. The current CDC travel notice to countries in or near the Arabian Peninsula is an Alert (Level 2), which provides special precautions for travelers. Because spread of MERS has occurred in healthcare settings, the alert advises travelers going to countries in or near the Arabian Peninsula to provide healthcare services to practice CDC’s recommendations for infection control of confirmed or suspected cases and to monitor their health closely. Travelers who are going to the area for other reasons are advised to follow standard precautions, such as hand washing and avoiding contact with people who are ill. See MERS in the Arabian Peninsula for more information.

CDC has also released a Watch (Level 1) travel notice for the Republic of Korea that reminds travelers to practice usual precautions. See MERS in the Republic of Korea for more information.

For information about cases and deaths by country, visit World Health Organization (WHO).

Learn more about MERS in the U.S.