Middle East respiratory syndrome (MERS) is caused by a coronavirus. First identified in Saudi Arabia in 2012, the virus still causes local outbreaks today.

MERS is caused by the Middle East respiratory syndrome coronavirus (MERS-CoV). Most people who develop the syndrome have severe respiratory symptoms.

MERS is different from coronavirus disease 19 (COVID-19). These conditions are caused by different types of coronaviruses. Learn more about COVID-19 here.

This article takes a close look MERS, including its symptoms, causes, and treatments. It also explores other conditions caused by coronaviruses.

Stay informed with live updates on the current COVID-19 outbreak and visit our coronavirus hub for more advice on prevention and treatment.

a man wearing a facemask to protect him from MERS-CoVShare on Pinterest
The majority of cases of MERS occurred in Saudi Arabia.
Image credit: AFP via Getty Images.

MERS-CoV is a coronavirus. Coronaviruses are a large family of viruses that cause respiratory illnesses, including the common cold.

These viruses are zoonotic, meaning that they commonly infect animals and can transfer to humans.

MERS-CoV is one of three new coronaviruses that cause severe illness in humans. The other two are:

Since it was first identified in 2012, MERS-CoV has continued to cause sporadic, localized outbreaks.

Globally, authorities have reported 2,519 cases of MERS and 866 deaths, indicating that about 1 in 3 people with the condition, or 35%, die from it.

The Centers for Disease Control and Prevention (CDC) are continuing to monitor the prevalence of MERS throughout the world.

Cases of MERS have been reported in 27 countries, while 80% of the cases have occurred in Saudi Arabia.

The risk of developing MERS in the United States is very low. Only two people in the country have tested positive for MERS-CoV, and both have recovered. The two cases were reported in May 2014 — one in Florida and the other in Indiana.

The people who tested positive were healthcare workers who had lived in Saudi Arabia. It is likely that they developed the infection before traveling to the U.S.

The largest outbreaks of MERS to date have occurred in:

  • Saudi Arabia
  • the United Arab Emirates
  • South Korea

In 2015, the largest MERS outbreak outside the Middle East involved 185 people in South Korea and 1 person in China. It led to 38 deaths.

Research suggests that MERS-CoV originated in bats. It then likely spread from infected dromedary camels to humans.

According to the World Health Organization (WHO), most cases of MERS in humans have been transmitted by people in healthcare environments. However, evidence suggests that dromedary camels could also be a source of infection in humans.

The virus does not seem to pass easily from person to person unless there is close contact, as in a healthcare setting.

Researchers do not yet know how exactly camels are involved in transmitting this virus. They have identified MERS-CoV in camels in several countries in the Middle East, Africa, and South Asia.

The most common symptoms of MERS are a fever, a cough, and shortness of breath. People may also have gastrointestinal problems, such as diarrhea, nausea, or vomiting.

Pneumonia is a common complication. There have also been reports of organ failure linked with MERS, especially kidney failure.

The symptoms usually appear 5–6 days after exposure to the virus, but they may take 2–14 days to arise.

Some people transmit the virus without experiencing any symptoms, while some others with MERS experience minor symptoms.

People with severe symptoms may need to spend a long time in the hospital, receiving mechanical ventilation and intensive care.

The following groups of people are more susceptible to MERS-CoV infection and complications:

  • older adults
  • people with health conditions such as diabetes, chronic lung disease, kidney disease, or cancer
  • people with weakened immune systems, such as those receiving chemotherapy or immunosuppressant medication

Most of those who have died from MERS had preexisting, chronic medical conditions.

During the appointment, the doctor will ask about symptoms and recent activities, including travel.

To check for an active MERS-CoV infection, a doctor takes a sample from the person’s respiratory tract. Laboratory tests, including polymerase chain reaction tests, can confirm the presence of the virus.

Scientists can also tell whether a person has previously had a MERS-CoV infection by using blood tests to check for antibodies developed to combat the virus.

As the WHO explain, there is no cure or vaccine for MERS, but vaccines and treatments are currently under development.

Healthcare professionals will work to relieve a person’s symptoms and reduce the risk of complications.

People with severe symptoms may require oxygen therapy, a stay in the intensive care unit, and a mechanical ventilator to help them breathe.

To reduce the risk of MERS-CoV transmission, health authorities recommend:

  • frequently washing the hands with soap and water for at least 20 seconds at a time
  • avoiding undercooked meats and any food prepared in conditions that may not be hygienic
  • washing fruits and vegetables thoroughly
  • reporting any suspected cases to local health authorities
  • minimizing close contact with anyone who develops an acute respiratory illness with fever
  • wearing a medical mask
  • sneezing into a sleeve, flexed elbow, or a tissue, then immediately disposing of it
  • seeking immediate medical attention if an acute respiratory illness with a fever develops within 14 days of returning from travel

MERS-CoV is contagious, but the virus does not appear to pass between humans without close contact.

The WHO state that it is safe to consume camel meat and milk after appropriate pasteurization, cooking, or other heat treatments, but it may be advisable to avoid raw products.

They recommend general hygiene practices after visiting farms or markets where camels are present, such as washing the hands before and after touching the animals and avoiding contact with sick animals.

Travelers with chronic conditions, such as diabetes, renal failure, or chronic lung disease have a higher risk of contracting the virus and should take extra precautions.

MERS and COVID-19 are separate respiratory illnesses. They are caused by different viruses in the coronavirus family.

COVID-19 results from infection with the SARS-CoV-2 virus.

Like MERS-CoV, researchers believe that SARS-CoV-2 originated in bats. Scientists are currently working to determine how it transferred to humans.

SARS-CoV-2 emerged from Wuhan, China in December 2019, and the WHO declared a global pandemic on March 11, 2020.

Research indicates that COVID-19 has a similar clinical presentation to MERS but that the death rate is much lower — COVID-19 has a fatality rate of 2.3%, while MERS has a rate of 35%.

However, COVID-19 causes less severe symptoms consistently than MERS and SARS, so it can spread through the community more easily. Increased globalization has also contributed to the more rapid spread of COVID-19, compared with MERS.

The median age range of people who develop COVID-19 is similar to that of people affected by MERS and SARS: 49–57 years.

Complications of COVID-19 occur at a similar rate to those of SARS and are less common than complications of MERS.

The National Institute of Allergy and Infectious Diseases is currently building on earlier research into SARS and MERS to help develop treatments for COVID-19.

MERS is a severe respiratory illness caused by MERS-CoV, a coronavirus. It causes a fever, a cough, and shortness of breath.

The WHO do not currently recommend any travel or trade restrictions as MERS precautions.

Though they are uncommon, localized outbreaks of MERS still occur. Official organizations continue to monitor the prevalence of MERS and are working to develop a vaccine.