Generality
Middle East Respiratory Syndrome (MERS) is an infectious disease caused by a Coronavirus (MERS-CoV) first identified in 2012 in Saudi Arabia.
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MERS manifests itself with clinical features ranging from asymptomatic or mild disease to acute respiratory distress syndrome, up to multi-organ failure leading to death; the odds of a fatal outcome are high especially in subjects with underlying comorbidities (such as diabetes and chronic kidney disease ).
In most people, however, MERS-CoV infection manifests with fever, cough, and difficulty breathing.
Although most cases of MERS have arisen in Saudi Arabia and the United Arab Emirates, cases have also been reported in Europe, the United States and Asia in people who had traveled - or had contact with those who traveled - in Middle East.
Dromedaries and camels are implicated in direct or indirect transmission to humans, although the exact modes of transmission have not yet been confirmed. On the other hand, inter-human contagion appears to be limited and appears to occur mainly through droplets of saliva (droplets) or by direct contact.
At present, there is no specific drug treatment for MERS and hygiene measures to prevent the spread of the infection are crucial. Understanding the virus and the disease it causes is constantly evolving.
Characteristics of the virus
Middle East Respiratory Syndrome is caused by a virus belonging to the large Coronavirus family, called MERS-CoV (acronym for "Middle East Respiratory Syndrome Coronavirus").
Initially called N-CoV (New Corona Virus), this viral agent was first identified on September 24, 2012, in Saudi Arabia, by Egyptian virologist Ali Mohamed Zaki, who was subjected to the case of a 60-year-old who died of a severe and mysterious form of pneumonia.
The MERS virus (MERS-CoV) isolated from this patient had similar characteristics to that of severe acute respiratory syndrome (SARS-CoV).
MERS-CoV is a positive-sense, single-stranded RNA virus.
The genomic sequence indicates that MERS-CoV is closely related to some bat coronaviruses (hence the hypothesis that these animals could represent the natural reservoir of infection).
What are Coronaviruses?
These are viruses first identified in the 1960s. Their name derives from the characteristic "crown" shape visible under the electron microscope.
These microorganisms cause respiratory infections in both humans and animals. Some Coronaviruses cause trivial colds and mild respiratory tract infections, others are responsible for serious lung disorders, as in the case of SARS (infectious pneumonia that broke out in China in 2002, infecting eight thousand people and killing nearly eight hundred).
MERS and SARS: Differences
Middle Eastern respiratory syndrome has been called the "new SARS".
In fact, MERS-CoV, although distantly related to the Coronavirus that causes severe acute respiratory syndrome (they belong to the same virus family), has significant differences.
Based on current information, in fact, it seems that MERS-CoV is less easily transmitted between people than the SARS virus, but is capable of causing a more serious form of disease that correlates with a higher mortality rate (due to the death in about 30-40% of cases, compared to 10% of severe acute respiratory syndrome).
Infection
The mode of transmission of MERS-CoV has not yet been confirmed, however it seems possible inter-human contagion by respiratory route and through direct contact with infected camelids.
At the moment, investigations are underway to determine the source of the virus and the dynamics with which it has come to infect humans.
Transmission from animals to humans
So far, the hypotheses attribute to camels and dromedaries the role of vehicles of "human infection", as the genetic sequences examined show a close link between the virus found in these animals and the one that infects people in the same geographical area (Arabia Saudi, Qatar, Oman and Egypt).
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The natural reservoir of the infection, on the other hand, would be represented by bats.
Person-to-person transmission
Human-to-human transmission is possible. This mode of inter-human contagion, however, does not seem to be stably supported in all cases of disease. For this reason, the presence within the communities of "super-spreader" individuals is considered possible, capable of spreading the infection more quickly than others.
However, it has yet to be definitively established whether the virus is contracted by air (through respiratory particles emitted with coughing or sneezing) or through prolonged contact with infected people or objects contaminated by them.
Geographical distribution
So far, the majority of MERS cases have occurred in countries on the Arabian Peninsula.
From Saudi Arabia, MERS has spread to neighboring Middle Eastern countries, affecting Jordan, Qatar and the United Arab Emirates with small outbreaks.
Since its discovery in 2012, MERS-CoV infections have also been reported in Lebanon, Kuwait, Oman, Yemen, Algeria, Iran, Egypt, Tunisia, the Philippines and Malaysia.
The sporadic cases reported in Europe (France, Germany, Italy, United Kingdom, Holland and Greece) and in non-European countries (United States) concern people who have traveled to the Middle East or who have had close contact with travelers from these areas.
The first Italian case was reported on May 31, 2013 in Tuscany. Even if the chances of getting infected in Europe are low, the import of the virus from high-risk countries, such as the Arabian Peninsula, remains possible.
Situations more at risk
Of particular concern is the annual pilgrimage to Mecca, on the occasion of Ramadan, which could facilitate the further spread of the Coronavirus, given the migration of thousands of faithful to and from "Saudi Arabia (the country where" the epidemic broke out. and where the greatest number of deaths is recorded to date).
The first cases in South Korea
Since 20 May 2015, WHO has been notified of an outbreak of MERS in South Korea which has reached worrying data. As of 10 June 2015, 107 human cases of infection and nine deaths have been confirmed. "Patient zero" is a man 68-year-old returned to South Korea after a trip to the Arabian Peninsula, where the genome of the virus that is spreading in South Korea has been sequenced and has proven to be the same as that circulating in Middle Eastern countries.
Incubation period
Based on the information we have gathered to date, the incubation period for Middle Eastern Respiratory Syndrome is 5-6 days, but it can range from 2 to 14 days.
MERS presents with a "wide range of clinical manifestations: in some cases, it may be asymptomatic or give rise to mild disturbances; in others, it can cause acute respiratory distress syndrome and" multi-organ failure.
Almost all symptomatic patients present with breathing difficulties.
MERS is associated with high mortality in patients with comorbid disorders such as diabetes and renal insufficiency.
Symptoms
MERS-CoV infection typically presents as a sort of flu-like syndrome, with fever, chills, headache, muscle aches, arthralgia, and generalized malaise.
After about 7 days, however, symptoms worsen and dry cough and breathing difficulties occur, which rapidly progress to pneumonia in most patients. In some cases, the virus also causes gastrointestinal disturbances (abdominal pain, diarrhea, nausea and / or vomiting) and can lead to kidney failure or septic shock.
In people with chronic diseases (diabetes, kidney disease, cancer and lung disease), Middle East Respiratory Syndrome can complicate "severe acute respiratory failure and lead to death. At risk of a fatal outcome are the elderly and the immunosuppressed, in which the disease may have an atypical presentation.
Period of contagiousness
The period of contagiousness for MERS-CoV infection is unknown.
The greatest danger of contagion is run by remaining in close contact with a sick person in the acute phase. During an epidemic, most cases are the result of human-to-human transmission in the health care setting, especially when infection prevention and control measures are inadequate.
Diagnosis
- People who have difficulty breathing and malaise within 14 days of returning from a trip to the Middle East should see their doctor.
- It is not always possible to identify patients with MERS right away because, as with other respiratory infections, the first symptoms are nonspecific. Pneumonia is a common examination finding, but it is not always present.
- Diagnosis of MERS is established primarily through serological testing and isolation of the virus by polymerase chain reaction (PCR) techniques on respiratory specimens.
- Serological tests to determine whether a person has been infected with the MERS-CoV virus and has developed an immune response involves three distinct tests: ELISA or enzyme-linked immunosorbent (screening test), IFA or immunofluorescent assay (confirmatory test) ) and dosage of neutralizing antibodies (slower but definitive confirmation test).
Treatment
There are no specific antiviral therapies for MERS, but some pharmacological approaches are being evaluated.
At present, treatment is supportive and is established on the basis of the patient's clinical condition. MERS-CoV pneumonia can rapidly progress to acute respiratory failure, which requires mechanical ventilation and medical assistance to maintain vital organ functions.
Is there a vaccine?
Currently, there is no vaccine available to prevent MERS-CoV infection.
Prevention
For travelers going to or from endemic areas, the WHO advises to follow the general hygiene measures implemented for the control of other respiratory infections at risk of epidemic-pandemic.
On the basis of the current situation and the information available, in particular, it is encouraged to:
- Wash your hands frequently with soap and water (or alcoholic solutions);
- If your hands are dirty, try not to touch your eyes, nose or mouth;
- Respect good respiratory hygiene, such as sneezing or coughing into a handkerchief or with the elbow flexed, use a mask and throw the used handkerchiefs in a closed bin immediately after use;
- Avoid close contact with anyone showing symptoms of the disease (coughing and sneezing) or with potentially infected animals (in particular, camelids);
- Avoid eating raw or undercooked meat;
- Consume fruit and vegetables only if properly washed;
- Avoid drinking unpasteurized milk and non-bottled drinks.
To reduce the risk of contracting the infection, the World Health Organization advises against drinking raw milk or camel urine. People who visit farms, markets or other places where animals are present should avoid contact unnecessary with bats, camels or dromedaries.
In endemic areas, farmers and butchers should remember to wash their hands before and after touching camels and other animals, protect their faces and, when possible, use protective clothing, which should be removed and washed at the end of each working day.
Sick animals should never be slaughtered for consumption.
Risks for travelers
The Centers for Disease Control and Prevention (CDC) and the World Health Organization are closely monitoring the virus.
Currently, there is no restriction on travel to the Middle East or other places where the virus has been reported.
Risk of a pandemic
According to the "World Health Organization, Middle Eastern respiratory syndrome does not yet represent an" international health emergency, but a disease to be kept under close surveillance.
As of 31 May 2015, a total of 1,180 laboratory-confirmed human cases of MERS-CoV infection (483 deaths; 40% mortality) have been reported to the World Health Organization (WHO).
MERS-CoV continues to be a low-level endemic public health threat. However, the potential for the virus to mutate could translate into greater human-to-human transmissibility, which could increase its pandemic potential.
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