Middle East Respiratory Syndrome (MERS) is an illness caused by a virus (more specifically, a coronavirus) called Middle East Respiratory Syndrome Coronavirus (MERS-CoV). Most MERS patients developed severe respiratory illness with symptoms of fever, cough and shortness of breath. About 3 or 4 out of every 10 patients reported with MERS have died.

All cases are linked to the Arabian Peninsula

Health officials first reported the disease in Saudi Arabia in September 2012. Through retrospective (backward-looking) investigations, they 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.

People with MERS can spread it to others

MERS-CoV has spread from ill people to others through close contact, such as caring for or living with an infected person.

MERS can affect anyone. MERS patients have ranged in age from younger than 1 to 99 years old.

CDC continues to closely monitor the MERS situation globally. We are working with partners to better understand the risks of this virus, including the source, how it spreads, and how to prevent infections. CDC recognizes the potential for MERS-CoV to spread further and cause more cases globally and in the U.S. We have provided information for travelers and are working with health departments, hospitals, and other partners to prepare for this.

Middle East Respiratory Syndrome (MERS) is viral respiratory illness that is new to humans. It was first reported in Saudi Arabia in 2012 and has since spread to several other countries, including the United States. Most people infected with MERS-CoV developed severe respiratory illness, including fever, cough, and shortness of breath. Many of them have died.

Countries with Lab-Confirmed MERS Cases

Countries in or near the Arabian Peninsula that have reported MERS cases: Bahrain, Iran, Jordan, Kuwait, Lebanon, Oman, Qatar, Saudi Arabia, United Arab Emirates (UAE), and Yemen.

Countries outside of the Arabian Peninsula with travel-associated MERS cases: Algeria, Austria, China, Egypt, France, Germany, Greece, Italy, Malaysia, Netherlands, Philippines, Republic of Korea, Thailand, Tunisia, Turkey, United Kingdom (UK), and United States of America (USA).

Q: What is MERS?

A: Middle East Respiratory Syndrome (MERS) is a viral respiratory illness. Learn about MERS.

Q: Why is it sometimes called MERS-CoV?

A: MERS-CoV is the acronym for Middle East Respiratory Syndrome Coronavirus, the virus that causes MERS. When referring to the virus and not the illness, CDC uses “MERS-CoV.” When referring to the illness, CDC uses “MERS.” The virus was first reported in 2012 in Saudi Arabia. It is different from any other coronavirus that researchers have found in people before.

Countries with Lab-Confirmed MERS Cases

Countries in or near the Arabian Peninsula that have reported MERS cases: Bahrain, Iran, Jordan, Kuwait, Lebanon, Oman, Qatar, Saudi Arabia, United Arab Emirates (UAE), and Yemen.

Countries outside of the Arabian Peninsula with travel-associated MERS cases: Algeria, Austria, China, Egypt, France, Germany, Greece, Italy, Malaysia, Netherlands, Philippines, Republic of Korea, Thailand, Tunisia, Turkey, United Kingdom (UK), and United States of America (USA).

Q: What is the source of MERS-CoV?

A: MERS-CoV likely came from an animal source in the Arabian Peninsula. Researchers have found MERS-CoV in camels from several countries. Studies have shown that direct contact with camels is a risk factor for human infection with MERS-CoV. But we need more information to understand the interactions between humans and camels that are important for transmission.

Q: What are the symptoms and complications that MERS can cause?

A: Read about MERS symptoms and complications.

Q: How does the virus spread?

A: Learn about how MERS-CoV spreads.

Q: Has anyone in the United States gotten infected?

A: Yes, two patients in the U.S. tested positive for MERS-CoV infection, both in May 2014. Get the most up-to-date information about MERS in the U.S.

Q: Am I at risk for MERS-CoV infection in the United States?

A: 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 tested positive for MERS-CoV infection—both in May 2014 after recently traveling from Saudi Arabia—while more than 1,300 have tested negative. CDC continues to closely monitor the situation. Read to find out if you are at increased risk for MERS-CoV infection.

Q: How can I help protect myself?

A: Visit the MERS prevention and treatment page to learn about how to protect yourself from respiratory illnesses, like MERS.

Also see Interim Guidance for Preventing MERS-CoV from Spreading in Homes and Communities. This guidance is intended for caregivers, household members, and other close contacts of people confirmed to have, or being evaluated for, MERS-CoV infection.

Q: What should I do if I had close contact with someone who has MERS?

A: If you have had close contact(1) with a confirmed MERS case within the last 14 days without using the recommended infection control precautions, you should contact a healthcare provider for an evaluation. See People Who May Be at Increased Risk for MERS. Person-to-person spread of MERS-CoV, usually after close and prolonged contact such as caring for or living with an infected person, has been well documented.

It’s important to note, however, that most people who had close contact with someone who had MERS did not get infected or become ill.

Q: Can I still travel to the Arabian Peninsula or neighboring countries where MERS cases have occurred?

A: Yes, there are currently no travel restrictions for the Arabian Peninsula.

Q: What if I recently traveled to the Arabian Peninsula or neighboring countries and got sick?

A: If you develop a fever(3) and symptoms of respiratory illness, such as cough or shortness of breath, within 14 days after traveling from countries in or near the Arabian Peninsula(2), you should call ahead to a healthcare provider and mention your recent travel. See People Who May Be at Increased Risk for MERS.

Q: What should I do if I had close contact with a recent traveler from the Arabian Peninsula?

A: If you have had close contact(1) with someone within 14 days after they traveled from a country in or near the Arabian Peninsula(2), and the traveler has/had fever(3) and symptoms of respiratory illness, such as cough or shortness of breath, you should monitor your health for 14 days, starting from the day you were last exposed to the ill person. If you develop fever(3) and symptoms of respiratory illness, such as cough or shortness of breath, you should call ahead to a healthcare provider and mention your recent contact with the traveler. See People Who May Be at Increased Risk for MERS.

Q: Does the U.S. detain arriving travelers who they believe have MERS?

A: CDC may detain individuals arriving in the U.S. or traveling between states who they believe are infected with a quarantinable disease, including MERS, as of July 31, 2014, per amended U.S. Executive Order 13295. “Isolation” is used to separate ill people who have a contagious disease from those who are healthy; “quarantine” is used to separate and restrict the movement of well people who may have been exposed to a contagious disease to see if they become ill. See About Quarantine and Isolation.

Q: Is there a vaccine?

A: Currently, there is no vaccine available to protect against MERS.

Q: What are the treatments?

A: Learn about MERS treatment.

Q: Should I be tested for MERS?

A: If you develop a fever(3) and symptoms of respiratory illness, such as cough or shortness of breath, within 14 days after travel from a country in or near the Arabian Peninsula(2), you should call ahead to a healthcare provider and mention your recent travel or close contact. If you have had close contact(1) with someone showing these symptoms who has recently traveled from this area, you should call ahead to a healthcare provider and mention your recent travel or close contact. Your healthcare provider will work with your state’s public health department to test you for MERS.

Q: How do you test a person for MERS?

A: There are two main ways to determine if a person is, or has been, infected with MERS-CoV.

• One type of test, conducted by state and CDC labs, is called PCR, or polymerase chain reaction, assays.
  • PCR assays are done with respiratory, serum, or stool samples and can quickly indicate if a person has an active infection with MERS-CoV.
• A second type of test, conducted by CDC lab, is called serology testing.
  • Serology testing uses serum samples and is designed to look for antibodies to MERS-CoV that would indicate a person had been previously infected with the virus and developed an immune response or has an active MERS-CoV infection for approximately 14 or more days.
  • Serology for MERS-CoV often includes two separate tests – (1) a screening test called ELISA or enzyme-linked immunosorbent assay and (2) a more definitive confirmatory test called the neutralizing antibody assay.

Q: What should healthcare providers and health departments do?

A: For recommendations and guidance on the case definitions; infection control, including personal protective equipment guidance; home care and isolation; case investigation; and specimen collection and shipment, see Information for Healthcare Professionals.

Q: Is MERS-CoV the same as the SARS virus?

A: No. MERS-CoV is not the same coronavirus that caused severe acute respiratory syndrome (SARS) in 2003. However, like the SARS virus, MERS-CoV is most similar to coronaviruses found in bats. CDC is still learning about MERS.

MERS-CoV, like other coronaviruses, likely spreads from an infected person’s respiratory secretions, such as through coughing. However, we don’t fully understand the precise ways that it spreads.

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. Researchers studying MERS have not seen any ongoing spreading of MERS-CoV in the community.

All reported cases have been linked to countries in and near the Arabian Peninsula. Most infected people either lived in the Arabian Peninsula or recently traveled from the Arabian Peninsula before they became ill. A few people have gotten MERS after having close contact with an infected person who had recently traveled from the Arabian Peninsula. The largest known outbreak of MERS outside the Arabian Peninsula occurred in the Republic of Korea in 2015 and was associated with a traveler returning from the Arabian Peninsula.

Public health agencies continue to investigate clusters of cases in several countries to better understand how MERS-CoV spreads from person to person.

Recent Travelers from the Arabian Peninsula

If you develop a fever* and symptoms of respiratory illness, such as cough or shortness of breath, within 14 days after traveling from countries in or near the Arabian Peninsula**, you should call ahead to a healthcare provider and mention your recent travel.

Close Contacts of an Ill Traveler from the Arabian Peninsula

If you have had close contact*** with someone within 14 days after they traveled from a country in or near the Arabian Peninsula**, and the traveler has/had fever* and symptoms of respiratory illness, such as cough or shortness of breath, you should monitor your health for 14 days, starting from the day you were last exposed to the ill person.

If you develop fever* and symptoms of respiratory illness, such as cough or shortness of breath, you should call ahead to a healthcare provider and mention your recent contact with the traveler.

Close Contacts of a Confirmed Case of MERS

If you have had close contact*** with someone who has a confirmed MERS-CoV infection, you should contact a healthcare provider for an evaluation. Your healthcare provider may request laboratory testing and outline additional recommendations, depending on the findings of your evaluation and whether you have symptoms. You most likely will be asked to monitor your health for 14 days, starting from the day you were last exposed to the ill person. Watch for these symptoms:

• Fever*. Take your temperature twice a day.
• Coughing
• Shortness of breath
• Other early symptoms to watch for are chills, body aches, sore throat, headache, diarrhea, nausea/vomiting, and runny nose.

If you develop symptoms, call ahead to your healthcare provider as soon as possible and tell them about your possible exposure to MERS-CoV so the office can take steps to keep other people from getting infected. Ask your healthcare provider to call the local or state health department.

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Healthcare Personnel Not Using Recommended Infection-Control Precautions

Healthcare personnel should adhere to recommended infection control measures, including standard, contact, and airborne precautions, while managing symptomatic close contacts, persons under investigation, and patients who have probable or confirmed MERS-CoV infections. They should also use recommended infection control precautions when collecting specimens.

Healthcare personnel who had close contact*** with a confirmed case of MERS while the case was ill, if not using recommended infection control precautions (e.g., appropriate use of personal protective equipment), are at increased risk of developing MERS-CoV infection. These individuals should be evaluated and monitored by a healthcare professional with a higher index of suspicion. For more information, see Interim Infection Prevention and Control Recommendations for Hospitalized Patients with Middle East Respiratory Syndrome Coronavirus (MERS-CoV).

People with Exposure to Camels

Direct contact with camels is a risk factor for human infection with MERS-CoV.

The World Health Organization has posted a general precaution for anyone visiting farms, markets, barns, or other places where animals are present. Travelers should practice general hygiene measures, including regular handwashing before and after touching animals, and avoiding contact with sick animals. Travelers should also avoid consumption of raw or undercooked animal products. For more information, see WHO’s Frequently Asked Questions on MERS-CoV. (Should people avoid contact with camels or camel products? Is it safe to visit farms, markets, or camel fairs?)

The World Health Organization considers certain groups to be at high risk for severe MERS. These groups include people with diabetes, kidney failure, or chronic lung disease, and people who have weakened immune systems. The World Health Organization recommends that these groups take additional precautions:

• Avoid contact with camels
• Do not drink raw camel milk or raw camel urine
• Do not eat undercooked meat, particularly camel meat

*Fever may not be present in some patients, such as those who are very young, elderly, immunosuppressed, or taking certain medications. Clinical judgement should be used to guide testing of patients in such situations.

**Countries considered in and near the Arabian Peninsula include: Bahrain; Iraq; Iran; Israel, the West Bank, and Gaza; Jordan; Kuwait; Lebanon; Oman; Qatar; Saudi Arabia; Syria; the United Arab Emirates (UAE); and Yemen.

***Close contact is defined as a) being within approximately 6 feet (2 meters), or within the room or care area, of a confirmed MERS case for a prolonged period of time (such as caring for, living with, visiting, or sharing a healthcare waiting area or room with, a confirmed MERS case) while not wearing recommended personal protective equipment or PPE (e.g., gowns, gloves, NIOSH-certified disposable N95 respirator, eye protection); or b) having direct contact with infectious secretions of a confirmed MERS case (e.g., being coughed on) while not wearing recommended personal protective equipment. See CDC’s Interim Infection Prevention and Control Recommendations for Hospitalized Patients with MERS. Data to inform the definition of close contact are limited; considerations when assessing close contact include the duration of exposure (e.g., longer exposure time likely increases exposure risk) and the clinical symptoms of the person with MERS (e.g., coughing likely increases exposure risk). Special consideration should be given to those exposed in healthcare settings. For detailed information regarding healthcare personnel (HCP) please review CDC’s Interim U.S. Guidance for Monitoring and Movement of Persons with Potential Middle East Respiratory Syndrome (MERS-CoV) Exposure. Transient interactions, such as walking by a person with MERS, are not thought to constitute an exposure; however, final determination should be made in consultation with public health authorities.

Most people confirmed to have MERS-CoV infection have had severe respiratory illness with symptoms of:

• fever
• cough
• shortness of breath

Some people also had diarrhea and nausea/vomiting. For many people with MERS, more severe complications followed, such as pneumonia and kidney failure. About 3 or 4 out of every 10 people reported with MERS have died. Most of the people who died had a pre-existing medical condition that weakened their immune system, or an underlying medical condition that hadn’t yet been discovered. Medical conditions sometimes weaken people’s immune systems and make them more likely to get sick or have severe illness.

Pre-existing conditions among people who got MERS have included

• diabetes
• cancer
• chronic lung disease
• chronic heart disease
• chronic kidney disease

Some infected people had mild symptoms (such as cold-like symptoms) or no symptoms at all.

The symptoms of MERS start to appear about 5 or 6 days after a person is exposed, but can range from 2 to 14 days.

A: There are two main ways to determine if a person is, or has been, infected with MERS-CoV.

• One type of test, conducted by state and CDC labs, is called PCR, or polymerase chain reaction, assays.
  • PCR assays are done with respiratory, serum, or stool samples and can quickly indicate if a person has an active infection with MERS-CoV.
• A second type of test, conducted by CDC lab, is called serology testing.
  • Serology testing uses serum samples and is designed to look for antibodies to MERS-CoV that would indicate a person had been previously infected with the virus and developed an immune response or has an active MERS-CoV infection for approximately 14 or more days.
  • Serology for MERS-CoV often includes two separate tests – (1) a screening test called ELISA or enzyme-linked immunosorbent assay and (2) a more definitive confirmatory test called the neutralizing antibody assay.

In general, these lab tests fall into two categories:

• Molecular tests, which look for evidence of active infection; and
• Serology tests, which look for previous infection by detecting antibodies to MERS-CoV. Serology tests are for surveillance or investigational purposes and not for diagnostic purposes.

Molecular Tests

Molecular tests are used to diagnose active infection (presence of MERS-CoV) in people who are thought to be infected with MERS-CoV based on their clinical symptoms and having links to places where MERS has been reported.

• Real-time reverse-transcription polymerase chain reaction (rRT-PCR) assays are molecular tests that can be used to detect viral RNA in clinical samples. CDC’s current case definition for laboratory confirmation of MERS-CoV infection requires either a positive rRT-PCR result for at least two specific genomic targets, or a single positive target with sequencing of a second target.
• Most state laboratories in the United States are approved to test for MERS-CoV by using an rRT-PCR assay developed by CDC. This test is done under authority of an Emergency Use Authorization because there are no FDA-cleared/approved tests available for this purpose in the United States.
• The success of rRT-PCR testing depends on several factors, including the experience and expertise of laboratory personnel, laboratory environment (e.g., avoidance of contamination), and the type and condition of specimens being tested. For this rRT-PCR assay, CDC recommends collecting multiple specimens, including lower (bronchalveolar lavage, sputum and tracheal aspirates) and upper (e.g., nasopharyngeal and oropharyngeal swabs) respiratory samples, serum, and stool specimens.
• CDC considers a person under investigation to be negative for active MERS-CoV infection following one negative rRT-PCR test on the recommended specimens. Since a single negative result does not completely rule out MERS-CoV infection, in some circumstances additional specimens may be tested.
• CDC considers a known MERS patient to be negative for active MERS-CoV infection following two consecutive negative rRT-PCR tests on all specimens.

Serology Tests

Serology testing is used to detect previous infection (antibodies to MERS-CoV) in people who may have been exposed to the virus. Antibodies are proteins produced by the body’s immune system to attack and kill viruses, bacteria, and other microbes during infection. The presence of antibodies to MERS-CoV indicates that a person had been previously infected with the virus and developed an immune response.

• Evidence to date suggests there may be a broader range of MERS disease than was initially thought. For example, public health investigators have identified individuals who are PCR-positive but have no MERS symptoms; we do not know if MERS-CoV can be spread by these people. For this reason, public health scientists are working to learn more about how the virus is transmitted. One way to do this is through voluntary testing of blood samples from people who had close contact with people known to have MERS.
• CDC has a two-phase approach for serology testing, using two screening tests and one confirmatory test to detect antibodies to MERS-CoV.
  • ELISA, or enzyme-linked immunosorbent assay, is a screening test used to detect the presence and concentration of specific antibodies that bind to a viral protein. CDC tests by ELISAS for antibodies against two different MERS-CoV proteins, the nucleocapsid (N) and spike (S).
    • If a clinical sample is determined to be antibody-positive by either ELISA, CDC then uses the microneutralization test to confirm the positive result.
  • The microneutralization assay is a highly specific confirmatory test used to measure neutralizing antibodies, or antibodies that can neutralize virus. This method is considered a gold standard for detection of specific antibodies in serum samples. However, compared with the ELISA, the microneutralization assay is labor-intensive and time-consuming, requiring at least 5 days before results are available.
    • If a clinical sample is positive by either ELISA, and positive by microneutralization, the specimen is determined to be confirmed positive.
    • If a clinical sample is positive by both ELISAs, and negative by microneutralization, the sample is determined to be indeterminate.
    • If a clinical sample is positive by only one ELISA, and negative by microneutralization, the sample is determined to be negative.
    • If a clinical sample is negative by both ELISAS, the sample is determined negative.
  • In the end, a final determination of a confirmed positive serology result requires a positive ELISA test and confirmation by microneutralization assay.
• MERS-CoV serology tests are for surveillance or investigational purposes and not for diagnostic purposes—they are tools developed in response to the MERS-CoV outbreak.
• Information is limited about MERS-CoV and how the virus is spread. As public health scientists learn more about MERS-CoV, the approach to conducting these types of laboratory tests might change.

There is no specific antiviral treatment recommended for MERS-CoV infection. Individuals with MERS often receive medical care to help relieve symptoms. For severe cases, current treatment includes care to support vital organ functions.

There is currently no vaccine to protect people against MERS. But scientists are working to develop one.

You can help reduce your risk of getting respiratory illnesses:

• Wash your hands often with soap and water for at least 20 seconds, and 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 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.

What is Middle East Respiratory Syndrome (MERS)?

Middle East Respiratory Syndrome (MERS) is caused by the virus MERS-CoV. Scientists do not fully understand how the virus spreads. It is likely that a person infected with the virus spreads it to others when they cough or sneeze. The virus spreads through the air to people very near the sick person, such as people who live with or care for them.

The link between camels, humans, and MERS is unclear, but touching camels or being around camels or their products (urine, milk, etc.) may make a person more likely to get MERS.

Common MERS symptoms include fever, cough, and shortness of breath. Some people also get diarrhea, nausea, and vomiting. Severe complications include pneumonia and kidney failure. MERS can cause death, but most people who die have an existing illness or disease such as diabetes, cancer, lung disease, heart disease, or kidney disease.

Who can get MERS?

Though MERS is rare, travelers to countries on or near the Arabian Peninsula can get sick. These countries include Bahrain, Iraq, Iran, Israel, the West Bank, and Gaza, Jordan, Kuwait, Lebanon, Oman, Qatar, Saudi Arabia, Syria, the United Arab Emirates (UAE), and Yemen.

People who are around people infected with MERS-CoV can get sick.

What can travelers do to prevent MERS?

There is no vaccine to prevent MERS, but there are steps you can take to protect yourself.

Avoid Germs:

• Wash your hands often with soap and water for at least 20 seconds.
• If soap and water aren’t available, clean hands with hand sanitizer containing at least 60% alcohol.
• Don’t touch your eyes, nose, or mouth. If you need to touch your face, make sure your hands are clean.
• Cover your mouth and nose with a tissue or your sleeve (not your hands) when coughing or sneezing.
• Try to avoid close contact, such as kissing, hugging, or sharing eating utensils or cups with people who are sick.

Avoid touching animals when traveling

• Do not touch live or dead animals.
• Do not use products made from wild animals.
• Avoid markets or farms with animals.
• Avoid touching materials, such as bedding, that are used by animals.

People with diabetes, kidney failure, or chronic lung disease, and people with weakened immune systems may be more likely to get severe MERS. People with these health conditions may want to:

• Avoid drinking raw camel milk or raw camel urine
• Avoid eating undercooked meat, particularly camel meat

If you traveled and feel sick, particularly if you have a fever, talk to a healthcare provider, and tell them about your travel. Avoid contact with other people while you are sick.