Middle Eastern Respiratory Syndrome (MERS)
Middle East Respiratory Syndrome (MERS) is an illness caused by a virus (MERS-CoV) that was first reported in Saudi Arabia in September 2012. MERS is caused by a virus that is transmitted from animals to humans. 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 camels sometime in the distant past.
Through retrospective (backward-looking) investigations, health officials later identified that the first known cases of MERS occurred in Jordan in April 2012. So far, all cases of MERS have been linked through travel to, or residence in, countries in and near the Arabian Peninsula. The largest known outbreak of MERS outside the Arabian Peninsula occurred in the Republic of Korea in 2015. The outbreak was associated with a traveler returning from the Arabian Peninsula.
Most people confirmed to have MERS–CoV infection have had severe acute respiratory illness with symptoms of fever, cough and shortness of breath. Some people also had gastrointestinal symptoms including diarrhea and nausea/vomiting. For many people with MERS, more severe complications followed, such as pneumonia and kidney failure. About 3 to 4 out of every 10 people reported with MERS have died. Most of the people who died had an underlying medical condition. Some infected people had mild symptoms (such as cold-like symptoms) or no symptoms at all; they recovered.
The incubation period for MERS (time between when a person is exposed to MERS-CoV and when they start to have symptoms) is usually about 5 or 6 days, but can range from 2 to 14 days.
MERS-CoV has been found in some camels. It is believed that humans can be infected through direct or indirect contact with infected dromedary camels in the Middle East. It is still unclear how the virus transmitted from camels to humans.
Once a person is infected with MERS-CoV, like other coronaviruses, is thought to spread to other people from an infected person’s respiratory secretions, such as through coughing. However, the precise ways the virus spreads are not currently well understood.
MERS-CoV has spread from ill people to others through close contact, such as caring for or living with an infected person. Infected people have spread MERS-CoV to others in healthcare settings, such as hospitals.
Molecular tests are used to diagnose people who are thought to be infected with MERS based on their clinical symptoms and having links to places where MERS has been reported (Saudia Arabia, Jordan, Qatar, or the United Arab Emirates). It is recommended that 3 specimens be collected for testing using molecular diagnostics (Real-time reverse transcription PCR); lower respiratory, upper respiratory and serum specimens. Respiratory specimens should be collected as soon as possible after symptoms begin —ideally within 7 days. However, if more than a week has passed since symptom onset and the patient is still symptomatic, respiratory samples should still be collected; especially lower respiratory specimens.
There is no specific antiviral treatment recommended for MERS infection. People with MERS often receive medical care to help relieve symptoms. For severe cases, current treatment includes care to support vital organ functions.
Currently, there is no vaccine to prevent MERS-CoV infection.
The MERS situation in the U.S. represents a very low risk to the general public in this country. Only two patients in the U.S. have ever tested positive for MERS infection—both in May 2014—while more than 800 have tested negative. In May 2014, CDC confirmed two unlinked imported cases of MERS in the United States – one to Indiana, the other to Florida. Both traveled to the U.S. from Saudi Arabia.
If you plan to travel to area where MERS has been found; avoid contact with camels, do not drink raw camel milk or raw camel urine and do not eat undercooked camel meat.
- Practicing good hand washing hygiene. Wash your hands often with soap and water for 20 seconds, and help young children do the same. If soap and water are not available, use an alcohol-based hand sanitizer.
- Covering 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 personal contact, such as kissing, or sharing cups or eating utensils, with sick people.
- Clean and disinfect frequently touched surfaces and objects, such as doorknobs.
- See the link below for a list of prevention steps for people confirmed to have or are being evaluated for infection with MERS.
For more information on prevention: Centers for Disease Control and Prevention (CDC)
Last reviewed March 2018