The MERS virus was first detected in September 2012 in a sample from a deceased patient in Saudi Arabia. Samples were then taken from a group of healthcare personnel in Jordan who became ill and the virus was detected in two who had died. In September 2012, the virus was detected in a man who was transferred from Qatar to the UK for intensive care. Since then, the virus has been detected in several countries in the Middle East. In some cases, infected individuals have travelled and further infected health institutions.
Up until September 2018, there were 2260 cases of MERS reported from 27 countries, of which 803 died.
Many cases are reported in spring, which may be due to seasonal variations in virus prevalence in the population of dromedary camels, although other factors may also play a role.
Most cases have been detected in Saudi Arabia. Some have been detected in Europe, Africa, Asia and America. Only a few cases of infection to third parties in countries outside the Middle East have been reported. Many of the cases have arisen in outbreaks in hospitals.
About MERS-CoV and transmission route
The coronavirus family includes many different viruses that usually cause respiratory infection. Many coronaviruses only cause common colds, but some may cause serious illness and sometimes death. Until 2012, the virus that causes MERS was a previously unidentified coronavirus.
Coronavirus is also found in animals. Studies performed early in the MERS outbreak showed that parts of the MERS virus resemble a virus found in bats. Subsequently, MERS-CoV has been detected in dromedary camels, and studies show that large parts of the dromedary camel population have been in contact with the virus. The virus has not been detected in other domestic animals except alpacas.
Disease and symptoms
The MERS virus has been detected in both critically ill patients and those with less severe symptoms, but so far the majority have become seriously ill. Secondary cases (people infected by other people) often show milder symptoms compared to the primary cases. The World Health Organization (WHO) and the European Centre for Disease Control (ECDC) issue regular information about the disease.
Most patients had symptoms such as fever and cough followed by severe pneumonia. Acute respiratory distress syndrome (ARDS) and multi-organ failure, renal failure, disseminated intravascular coagulation (DIC) and pericarditis (inflammation of the pericardium) have been seen among the critically ill. Some patients had diarrhoea and one patient who was on immunosuppressive treatment only had gastrointestinal symptoms. Some patients have been diagnosed with co-infection with influenza A, herpes simplex I or pneumococci.
The majority of those infected had chronic diseases and most of them were men, with an average age of about 50 years.
There are still several aspects concerning the source of infection and transmission mode that are unknown. Studies indicate that MERS is a zoonosis which is a disease transmitted from animals to humans. Humans probably get infected by the virus through direct and indirect contact with dromedary camels.
It has been seen that the virus to a certain degree can be transmitted from person to person. It is believed that coughing / droplets are the main route of infection between people, but other transmission routes cannot be excluded. Sustained virus transmission among humans has not been demonstrated. Contact tracing around MERS cases that have travelled by plane to countries outside the Middle East, has so far not resulted in detection of virus transmission to other passengers.
Studies show that the preliminary incubation period (time from infection to when symptoms occur) is somewhere between 1-13 days, although most people probably develop symptoms after 3-4 days.
Diagnosis and treatment
The virus can be detected in airway samples, particularly the lower airways. The Norwegian Institute of Public Health’s laboratory has diagnostic methods to detect the virus.
There is no specific treatment or vaccine for MERS. The disease is treated symptomatically, e.g. with mechanical ventilation when required. Prompt medical attention is important.
Prevention of MERS
There is no vaccine or preventive medicine against the disease. Good hand-hygiene is an important preventive measure which applies for all infections, including MERS. Avoid close contact with people with acute respiratory disease when travelling in the Middle East. Travellers are also recommended to avoid contact with animals, particularly dromedary camels in the Middle East. Avoid drinking camel milk and camel urine and do not eat meat that has not been thoroughly heat-treated. The term Middle East refers to countries around the eastern Mediterranean and eastward, in addition to the countries of the Persian Gulf. Turkey is not considered to be part of the Middle East.
Studies into the use of face masks have not been able to document a positive health effect of healthy people wearing them outside healthcare settings. Incorrect use is common, and people who use face masks touch their face more frequently, which may increase the risk of infection. Therefore, we do not recommend that healthy people use face masks. We have issued different recommendations for healthcare professionals and others who treat patients. People who have been infected may also wear face masks to avoid spreading the virus.
When should medical help be sought?
If you have been in the Middle East or been in contact with MERS patients during the past 14 days and have symptoms of pneumonia, consult your physician. Patients hospitalised with symptoms of severe respiratory disease and who have been in the Middle East during the past 14 days should be tested for MERS-CoV and other possible infections. Physicians should be aware that patients on immunosuppressive therapy may display different symptoms than respiratory symptoms following MERS infection.
The travel advice for MERS applies particularly when travelling to Middle Eastern countries.
Most cases of MERS have originated in Saudi Arabia. A few have been diagnosed in Europe, either because they were transferred to a European country for intensive care, or because they became ill after staying in the Arabian Peninsula. In some countries, it has also been transmitted to close contacts, including other patients and staff in hospitals.