MERS CoV

Coronaviruses are a large, diverse group of viruses that affect many animal species. A few of these viruses cause a wide range of respiratory illness in humans, typically with common cold symptoms. A novel coronavirus was identified in 2012, which has been named Middle East respiratory syndrome coronavirus (MERS-CoV). The first patient was a 60 year old man from Saudi Arabia, who was hospitalized in June 2012 and subsequently died. The second patient was a 49 year old man from Qatar who developed pulmonary and renal failure in September 2012.

Genetic sequence data indicated that this novel coronavirus is a beta-coronavirus similar to bat coronaviruses and unrelated to any other coronavirus described in humans, including the coronavirus that caused severe acute respiratory syndrome (SARS).

MERS-CoV is a zoonotic virus transmitted sporadically from camels to humans. Most reported human MERS cases have occurred in or near the Arabian Peninsula. Camel-to-human transmission has also occurred in Africa and South Asia. Travel-associated cases have occurred in at least 17 countries outside of the Arabian Peninsula. Between 2017 and 2023, 721 cases of MERS have been reported globally. 

Limited human-to-human transmission can occur after close contact. Large hospital-based outbreaks occurred in South Korea in 2015. On May 20, 2015, the Republic of Korea reported to WHO a case of laboratory-confirmed  MERS-CoV infection. The index case was a 68 year-old male who travelled to Bahrain, United Arab Emirates (UAE), Kingdom of Saudi Arabia (KSA), and Qatar, prior to returning to Korea on May 4. He subsequently became ill and sought medical care at several healthcare facilities before being diagnosed with MERS-CoV on May 20. More than 100 healthcare workers became ill and 9 died. This was the largest outbreak of MERS-CoV outside of the Arabian Peninsula.

The United States has been doing nationwide surveillance for MERS-CoV since 2012. Two patients tested positive for MERS-CoV in May 2014. The first patient was a health care worker employed in Saudi Arabia who returned to the United States on April 27, 2014 and was hospitalized in Indiana on April 28, 2014. The second case involved a traveler from Saudi Arabia who was hospitalized in Florida on May 11, 2014. Since then, no other cases have been identified in the United States. 

Most cases of MERS have occurred among older adults. Common signs and symptoms include: fever, dyspnea, non-productive cough, chills and rigors, headache, and myalgia. Most patients who develop severe illness requiring hospitalization have had pre-existing medical conditions. These patients often exhibit rapidly progressive pneumonia, acute respiratory distress syndrome (ARDS), refractory hypoxemia, and respiratory failure. Globally, the mortality rate of MERS cases is approximately 35%. Treatment is supportive because no specific therapy has been shown to be effective. 

Public health laboratories offer PCR testing for MERS-CoV. MERS-CoV RNA has been detected in survivors for a month or more after onset, and live virus has been cultured up to 25 days after onset. 

CDC recommends collecting multiple specimens for PCR testing including: bronchoalveolar lavage, sputum and tracheal aspirates and upper nasopharyngeal and oropharyngeal swabs.

In 2024, CDC released updated criteria for testing for MERS-CoV infection. MERs-CoV infection should be considered in patients who meet the following criteria:

Patient with severe illness such as fever AND pneumonia or acute respiratory distress syndrome AND one of the following: 

• A history of travel from countries in or near the Arabian Peninsula within 14 days before symptom onset, OR close contact with a symptomatic traveler who developed fever and acute respiratory illness (not necessarily pneumonia) within 14 days after traveling from countries in or near the Arabian Peninsula, OR 
• A history of direct contact with camels in North, West, or East Africa within 14 days before symptom onset, OR
• A member of a cluster of patients with severe acute respiratory illness (e.g., fever and pneumonia requiring hospitalization) of unknown etiology, OR
• High risk occupational exposure to MERS-CoV such as laboratory or research personnel 

Patients with milder illness (fever, cough, and/or shortness of breath) with no other alternative diagnosis and at least one of the following epidemiological risk factors:

• A history of being in a healthcare facility (as a patient, worker, or visitor) within 14 days before symptom onset in a country or territory in or near the Arabian Peninsula in which MERS has been identified OR
• A  history of direct contact with a camel in or near the Arabian Peninsula within. 14 days of symptom onsetOR
• A history of close contact with a person with confirmed MERS-CoV infection while that person was ill OR
• High risk occupational exposure to MERS-CoV, such as laboratory or research personnel. 

References

Zaki AM, van Boheemen S, Bestebroer TM, Osterhaus AD, Fouchier RA. Isolation of a novel coronavirus from a man with pneumonia in Saudi Arabia. N Engl J Med 2012;367:1814–20.

Arabi YM, Balkhy HH, Hayden FG, et al. Middle East respiratory syndrome. N Engl J Med . 2017;376(6):584–94

Killerby ME, Biggs HM, Midgley CM, Gerber SI, Watson JT. Middle East respiratory syndrome coronavirus transmission. Emerg Infect Dis 2020;26:191–8.

Morbidity and Mortality Weekly Report (MMWR)  May 16, 2014 / 63(19);431-436, (http://www.cdc.gov/mmwr).

Lambrou AS, South E, Midgley CM, et al. Update on the Epidemiology of Middle East Respiratory Syndrome Coronavirus — Worldwide, 2017–2023. MMWR Morb Mortal Wkly Rep 2025;74:313–320.