Middle East Respiratory Syndrome (MERS) is a viral respiratory disease that is caused by a coronavirus (the coronavirus that causes Middle East Respiratory Syndrome or MERS-CoV) that was first detected in Saudi Arabia in 2012. Coronaviruses are a large family of viruses that cause illness in humans ranging from the common cold to severe acute respiratory syndrome (SARS).
Since 2012, MERS cases have been confirmed in 27 countries: Algeria, Austria, Bahrain, China, Egypt, France, Germany, Greece, Italy, Jordan, Kuwait, Lebanon, Malaysia, Netherlands, Oman, Philippines, Qatar, Republic of Korea, Saudi Arabia, Thailand, Tunisia, Turkey, United Arab Emirates, United Kingdom, United States of America and Yemen.
Almost 80% of human cases have been certified in Saudi Arabia. Cases located outside the Middle East are usually from travelers who have become infected in this region. Although few, there have also been some outbreaks outside the Middle East.
MERS-CoV is mainly transmitted from animals to people, but it can also be spread from person to person.
Transmission from animals to people
MERS-CoV is a zoonotic virus, that is, it is transmitted from animals to humans. Scientific data show that humans become infected due to direct or indirect contact with infected dromedaries. MERS-CoV has been known to occur on dromedaries in several countries, including Egypt, Oman, Qatar and Saudi Arabia. Some data also indicate that MERS-CoV is widespread among dromedaries in the Middle East, Africa, and some sites in South Asia. It is likely to be found in other animal reservoirs, although goats, cows, sheep, buffaloes, pigs and wild birds have been studied without known positive MERS-CoV results.
MERS-CoV is not easily spread from one person to another, only in cases of relative intimacy, such as when caring for patients who are infected without taking the correct hygienic measures. Until now, person-to-person transmission has been limited and has existed among family members, patients and medical professionals. The vast majority of known cases of MERS to date occurred in the healthcare setting, although to date no sustained person-to-person transmission has been demonstrated anywhere on the planet.
Common symptoms of SEM are fever, cough and breathing difficulties. Pneumonia is common, although in some cases no symptoms have occurred. Gastrointestinal symptoms, particularly diarrhea, have also been reported. In its severe version, the disease can cause respiratory failure, which requires mechanical ventilation and support in an intensive care unit.
Some patients may manifest some type of organic dysfunction, most commonly kidney failure or septic shock. This virus is suspected of causing aggravation of the disease in immunosuppressed patients, the elderly and people with chronic diseases such as diabetes, cancer and chronic lung disease. The mortality rate is high, at almost 35%, although this figure may be higher than the actual one, as it is very possible that the less severe cases are not diagnosed by the current surveillance systems.
Currently, there is no vaccine for the cure of the disease that causes MERS, nor is there any specific treatment. Treatment is supportive and depends on the patient’s clinical status.
In some patients the infection does not appear to have symptoms. These cases have been detected because these people were tested for MERS-CoV as part of the contact investigation of people infected with the virus.
It is not always possible to early identify people infected with MERS-CoV because the initial symptoms of the disease are nonspecific and because of their similarity are often confused with those of other respiratory diseases. Because of this, all health centers must implement standardized infection prevention and control actions. In addition, it is of great relevance to investigate the travel history of people with symptoms of respiratory infections to verify if they have been recently in a country where the circulation of MERS-CoV is active or if they have been in contact with dromedaries.
It is contagious, but person-to-person transmission has been limited so far. There is no evidence that the virus is easily transmitted from one person to another, unless there is close contact, for example, when caring for an infected patient without proper protection. There have been clusters of cases in health care settings where human-to-human transmission is most likely, especially when prevention and infection control practices are not correct. The largest healthcare-associated outbreaks occurred in Saudi Arabia and the Republic of Korea.
People who have been in close contact with an MERS-infected person are at increased risk of infection and may infect others if they begin to show symptoms. Placing such persons under observation within 14 days of the last exposure to the virus will ensure that they get the necessary care and treatment, and will prevent further transmission of the virus to others.
The process of tracking this virus in the people and people close to them with whom you have been visiting is called contact tracing and it consists of three essential stages:
- Contact identification: when a case is confirmed, possible contacts are sought and questions are asked about the activities of the infected person and the activities and role of the people who have been with the person since the onset of the disease. Contacts can be family members or anyone who has been in contact with the person, such as colleagues at work, social events or health centres.
- Contact list: all persons considered to have been in contact with a confirmed case should be included in the contact list. It is imperative to try to find each contact on the list and inform them of their contact status, what this means, what actions will be taken and the importance of receiving early care if they have any of the symptoms. The contact should also receive information about prevention of the disease. In some cases, some contacts with a high risk of contracting the disease will have to be placed in quarantine or isolation, this can be at home or in the hospital, depending on the characteristics of each case.
- Contact follow-up: every person who has been established as a contact must be followed daily for 14 days, counting from the last time they had contact with a confirmed MERS case. The purpose of this is to locate the possible occurrence of signs and symptoms of MERS and to test for the virus.