About Middle East Respiratory Syndrome (MERS)

What it is

Middle East Respiratory Syndrome (MERS) is a viral respiratory illness caused by a coronavirus called Middle East respiratory syndrome coronavirus (MERS-CoV). The virus can spread from camels to people through direct physical contact. Limited human-to-human transmission is possible. MERS has caused severe respiratory disease in most diagnosed cases, and many of those patients died. Typical symptoms include fever, cough, and shortness of breath.

Most MERS cases have been detected in countries in or near the Arabian Peninsula. However, a number of cases linked to travel have been detected in countries outside this region.

For more information about travel guidelines for your destination, visit CDC's Travelers' Health site.

Signs and symptoms

Most people with confirmed MERS-CoV infection have had severe respiratory illness. MERS symptoms usually appear 5 or 6 days after a person is exposed. However, symptoms can appear as early as 2 days and up to 14 days after exposure.

Common symptoms of MERS include:

• Fever
• Cough
• Shortness of breath

Some people may also have diarrhea, nausea, or vomiting. It is also possible that someone with MERS may have only mild symptoms or no symptoms.

In most known MERS cases, the infected person developed pneumonia. Additional complications such as kidney failure have also occurred. About 3 or 4 out of every 10 people reported with a MERS infection died.

Most of the people who die from MERS had at least one preexisting medical condition. Certain conditions may increase the risk of getting severe complications from MERS. These include:

• Diabetes
• Cardiovascular disease, including high blood pressure
• Chronic lung disease
• Chronic heart disease
• Chronic kidney disease
• Cancer

Who is at risk

You may be at increased risk of getting MERS if you:

• Recently (in the past 14 days) returned from travel in or near the Arabian Peninsula, and especially if you also:
  • Worked in or visited a healthcare setting
  • Had direct physical contact with camels (including touching or grooming)
  • Had close contact with a person who was sick with fever or respiratory symptoms

• Had close contact in the past 14 days with someone who was sick with fever or respiratory symptoms of unknown cause after they had traveled in or near the Arabian Peninsula
• Had close contact in the past 14 days with someone who has tested positive for MERS

How it spreads

The virus that causes MERS can spread through respiratory secretions, such as saliva or mucous, of infected animals or people. The MERS virus is mostly found in camels (dromedaries), and direct physical contact with camels can lead to transmission to humans. People infected through contact with camels can then spread the virus to other people. All reported person-to-person transmissions of MERS have been linked to someone who had been in or near the Arabian Peninsula.

Large MERS outbreaks from person-to-person spread have occurred in healthcare facilities treating patients with MERS. Some spread can occur in households through close contact (like sharing a bed or caring for someone who is sick). The largest known outbreak of MERS outside the Arabian Peninsula occurred in the Republic of Korea in 2015. Multiple healthcare facilities were affected by the outbreak, which was associated with a traveler returning from the Arabian Peninsula.

Researchers continue to investigate clusters of MERS cases to better understand how the virus spreads.

Prevention

No vaccine exists to protect people against MERS. CDC's Respiratory Virus Guidance provides practical recommendations and information to help people lower health risks from respiratory viral illnesses.

For travelers, the World Health Organization recommends:

• Wash your hands before and after touching camels.
• Avoid drinking raw camel milk or camel urine or eating meat (including camel meat) that has not been properly cooked.
• If you are someone at higher risk for severe MERS illness, avoid close contact with camels.

Treatment

No specific antiviral treatment is recommended for MERS. People with MERS often receive supportive medical care and care to help relieve symptoms.