MERS-CoV: background information
This guidance gives advice on the transmission, diagnosis, treatment and prevention of Middle East respiratory syndrome coronavirus (MERS-CoV) to the public.
Applies to England
MERS-CoV: background information
Origin and spread of MERS-CoV
Middle East respiratory syndrome coronavirus (MERS-CoV) is a respiratory virus which can be transmitted from dromedary camels to humans (zoonotic transmission). MERS-CoV causes Middle East respiratory syndrome (MERS), a viral respiratory disease that was first identified in the Kingdom of Saudi Arabia and Jordan in 2012. MERS-CoV circulates in dromedary camels across the Middle East, parts of Africa, and South and Central Asia.
Since 2012, over 2,600 laboratory-confirmed cases of human infection with MERS-CoV have been reported to the World Health Organization (WHO). The majority of MERS cases have been reported from the Middle East. Approximately 84% of human cases have been reported by the Kingdom of Saudi Arabia.
Sporadic human cases and small clusters have been detected in countries outside of the Middle East, including the UK. These international cases have typically been found in individuals who had travelled from the Middle East.
Information on countries that pose an infection risk for MERS-CoV see below is available and regularly updated by the UK Health Security Agency (UKHSA). Travel advice for individuals travelling to these at-risk areas can be found on the National Travel Health Network and Centre (NaTHNaC) website.
Transmission
MERS-CoV primarily infects and transmits between dromedary camels. These animals typically do not show any symptoms as a result of the MERS-CoV infection. Camel-to-human transmission of the virus can occur when people come into direct contact with infected camels or have indirect contact by handling or consuming raw camel products such as meat, milk and urine. Despite our understanding that camel-to-human and human-to-human transmission of the virus can occur, the exact route of transmission has not yet been fully established.
Human-to-human transmission has been documented in individuals with close household contact with cases, and in healthcare workers managing cases. Evidence suggests that transmission from mild MERS cases is limited.
Outbreaks in hospitals have been reported from the Kingdom of Saudi Arabia, the United Arab Emirates and the Republic of Korea.
Clinical features
MERS-CoV infection in humans can cause a range of clinical presentations from mild to severe respiratory disease. Asymptomatic infections can also occur. Typical symptoms include fever, cough, and shortness of breath, which can progress to severe pneumonia, acute respiratory distress syndrome (ARDS), and multi-organ failure. Gastrointestinal symptoms such as diarrhoea and vomiting have also been reported. Despite the range of clinical presentations, death has occurred in 36% of MERS-CoV cases reported to date. Severe disease and death are more likely in older adults with chronic underlying health conditions such as diabetes, lung, cardiovascular or renal disease and cancer.
Diagnosis
Symptoms of MERS resemble those of many other acute respiratory infections; therefore, clinical diagnosis relies on identification of relevant travel history and risk factors due to the specific geography of the animal reservoir. Laboratory diagnosis is by reverse-transcriptase polymerase chain reaction (PCR) for viral RNA. In the UK, laboratory diagnosis is carried out by some NHS laboratories and the UKHSA Clinical Network Laboratories (CNLs).
Treatment and prevention
There is currently no vaccine available for MERS-CoV. Prevention of infection relies on avoidance of risk factors and adherence to travel advice, prompt identification of suspected cases and strict adherence to infection prevention and control guidance in healthcare settings.
There are no specific antiviral treatments for MERS-CoV, and management of human infection involves supportive treatment.
MERS-CoV: affected countries
MERS-CoV is primarily an infection of dromedary camels in the Middle East, Africa, South and Central Asia.
Two genetic groups (clades), B and C are in current circulation. Clade B has diversified into several sub-clades B1 to B5. Clade B5 is dominant in Saudi Arabian camels and has caused recent human cases. Several sub-clades of B5 are circulating in Kingdom of Saudi Arabia camels but have not been found in humans to date. Similarly, clade C, that is known to circulate among camels in Africa has also not been confirmed in any human cases.
Arabian Peninsula and Middle East
More than 90% of all human cases of MERS-CoV have been reported to have occurred in countries of the Arabian Peninsula, 84% of which are reported in the Kingdom of Saudi Arabia. The remaining 16% of human cases are reported from United Arab Emirates, Qatar, Oman, Kuwait, Bahrain, and Yemen. Human cases have also been reported from countries in the wider Middle Eastern region (Jordan, Iran, Lebanon, and Egypt).
In the Middle Eastern region, cases of MERS-CoV occur throughout the year, and camel contact remains a significant risk factor for infection. There is currently no evidence of sustained community transmission; limited human-to-human transmission can occur, particularly in healthcare facilities and household clusters. Outbreaks linked to healthcare facilities have occurred, but healthcare professionals have developed robust and effective infection prevention and control practices for possible cases that limit the potential for onward transmission to other patients and staff.
Europe, Africa, Asia, and Americas
Travel to countries in Europe, Africa, Asia and the Americas where MERS-CoV is not endemic in camels is not considered to be a risk for MERS-CoV infection.
Cases of MERS-CoV infection of humans have been detected in many countries globally, associated with individuals having a travel history from the Middle East region. The following countries have reported imported human MERS-CoV cases, Algeria, Austria, China, France, Germany, Greece, Italy, Malaysia, the Netherlands, Philippines, Republic of Korea, Thailand, Tunisia, Türkiye, the United Kingdom of Great Britain and Northern Ireland, and the United States of America.
A large outbreak of MERS-CoV occurred in Republic of Korea in 2015, started by individuals with a travel history to the Middle East, but involving person to person transmission in close contact household and hospital settings. Healthcare professionals globally have learned from events such as the Republic of Korea; effective infection prevention and control practices for possible cases that limit the potential for onward transmission to other patients and staff.
There is documented serological evidence of human infections in Kenya, in individuals with an occupational exposure to camels. Individuals in the UK with an occupational exposure to camels in Kenya are considered at risk of MERS-CoV infection.
In the UK there have been five confirmed cases of MERS-CoV human infection, as a result of 3 separate events involving individuals having a travel history to the Middle East.
Further information
The WHO factsheet on Middle East respiratory syndrome coronavirus (MERS-CoV) gives further information on MERS and the World Health Organization MERS-CoV dashboards provides a centralised visualization of confirmed human cases reported through the International Health Regulations and WHO Disease Outbreak News (DON).
UKHSA regularly assesses the risk of MERS-CoV to UK public health as a result of travellers to and from the Middle East, directly or via other countries, and works with NaTHNaC to provide travel and health advice.
UKHSA produces guidance for healthcare professionals on diagnosing and managing MERS-CoV cases and contacts.