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The Middle East respiratory syndrome coronavirus (MERS-CoV) is a new beta virus strain of an animal coronavirus that was first identified in Saudi Arabia in September 2012. This novel coronavirus differs from the previously identified coronaviruses such as the SARS coronavirus (SARS-CoV), which caused the 2003 SARS outbreaks.
There is still much to be investigated, but it is considered likely that this virus originated from an animal source.
Coronaviruses are enveloped RNA viruses from the Coronaviridae family and part of the Coronavirinae subfamily. With its characteristic surface, the virions appear as a crown like image under the electron microscope and so the viruses are named after the Latin word corona, meaning ‘crown’ or ‘halo’.
In animals the viruses infect the respiratory and gastrointestinal systems as well as occasionally affecting the liver and the neurological systems.
The human coronaviruses mainly infect the upper respiratory and gastrointestinal tract. They often result in upper respiratory tract infections (simple colds) in humans, causing mild illnesses usually of short lasting nature with a rhinitis, cough, sore throat, as well as fever.
Occasionally, the viruses are able to cause more significant lower respiratory tract infections in human with pneumonia; this is more likely in immunocompromised individuals, people with cardiopulmonary illnesses, as well as the elderly and young children. Only very rarely do the humans viruses cause severe disease, like sever acute respiratory syndrome.
The five coronaviruses types which affect humans are alpha (229E and NL63), beta (OC43), HKUI1 and SARS-CoV – although the latter is best considered an animal virus that has only rarely infected humans.
In humans, the transmission of coronaviruses between an infected individual and others can occur via respiratory secretions. This can happen either directly through droplets from coughing or sneezing, or indirectly through touching contaminated objects or surfaces as well as close contact, such as touching or shaking hands.
There are currently no vaccines or specific treatments for the coronaviruses. Hence, in order to reduce the risk and prevent the spread of infections, simple preventative measure are: good respiratory hygiene, including washing hands; avoiding touching one’s eyes, mouth and nose; sanitary disposal of oral and nasal discharges as well as avoiding contact with sick people.
Factsheet
Page last updated: 20 August 2014
Introduction
The pathogen
Clinical features and sequelae
Transmission
Diagnostics
Case management and treatment
Epidemiology of MERS-CoV in humans
Public health control measures
Advice to travellers
References
The information contained in this factsheet is intended for the purpose of general information and should not be used as a substitute for the individual expertise and judgement of healthcare professionals.
MERS-CoV is a newly identified coronavirus that has recently emerged in the Middle East. The evolutionary history of MERS-CoV and the reservoirs and hosts of human infection are still being studied, but, there are many indications that it is a zoonosis. All confirmed or possible cases diagnosed in the EU/EEA should immediately be reported by the national authorities to the Early Warning and Response System (EWRS) and to WHO under the International Health Regulations (IHR) (2005).
Since it was first identified in Saudi Arabia in September 2012, MERS-CoV has been detected in over 850 cases in over 20 countries. In Europe, six countries have reported confirmed cases, all with direct or indirect connection with the Middle East.
Clinical presentation of MERS-CoV infection ranges from asymptomatic to very severe pneumonia with acute respiratory distress syndrome (ARDS), septic shock and multi-organ failure resulting in death. The clinical course is more severe in immunocompromised patients.
Human-to-human transmission has been reported, e.g. by close contacts or in healthcare facilities. Nosocomial transmission has been a hallmark of MERS and the majority of cases has been reported from hospital outbreaks in Saudi Arabia and United Arab Emirates (UAE). There is growing evidence that the dromedary camel is a host species for the virus and that this species might play an important role in the direct or indirect transmission to humans.
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MERS-CoV is an enveloped, single-stranded, positive-sense RNA virus. The genome is approximately 30.1kb long and contains at least 10 predicted open reading frames (ORF), which are expressed from seven subgenomic mRNAs. These ORFs mainly include ORF 1a/1ab, which encode for large replicase polyproteins containing conserved functional domains and several non-structural (NS) proteins of CoV, the spike-surface glycoprotein (S), the small-envelope (E) protein, the matrix (M) protein, and the nucleocapsid (N) protein [1,2].
MERS-CoV belongs to lineage C within the Betacoronavirus genus (Coronavirinae subfamily), along with several viruses detected in bats in Europe, Africa and China [3]. MERS-CoV is the first Betacoronavirus lineage C member isolated from humans, and it is distinct from SARS and distinct from the common-cold coronavirus and known endemic human betacoronaviruses HCoV-OC43 and HCoV-HKU1, HCoV-NL63, and HCoV-229E [4].
Basis for sero-typing or other classification
MERS-CoV genomes are phylogenetically classified into two clades: clades A and B. The viral genomes detected in the earliest cases in humans (clade A cluster; EMC/2012 and Jordan-N3/2012) are genetically distinct from the others (i.e. clade B) [5]. Several virus sequences are available in GenBank including complete genome sequences from both humans and camels [6]. Multiple distinct MERS-CoV genotypes exist, possibly each from a separate zoonotic event [5,6]. However, all sequences from human and camel samples related to this epidemic in the Middle East are closely related, and many are identical.
Before the announcement of the MERS-CoV name by the Coronavirus Study Group, isolates of the virus were described in the scientific literature, databases, and popular press under various names (e.g. human betacoronavirus 2c EMC, human betacoronavirus 2c England-Qatar, human betacoronavirus 2C Jordan-N3, betacoronavirus England 1) with novel coronavirus (NCoV) as the one used most often [7].
MERS-CoV uses its spike protein to bind to the cellular receptor dipeptidyl peptidase 4 (DDP4; CD26) for entry to host cells [8]. As DDP4 has been evolutionarily conserved across animal species, MERS-CoV has a broad hypothetical host range. In humans, DPP4 is expressed particularly in lung and kidney cells [9].
Humans
Since March 2012, autochthonous MERS cases have been detected only in the Middle East (Saudi Arabia, United Arab Emirates, Jordan, Qatar, Oman, Kuwait, Yemen, Lebanon and Iran). MERS cases have also been detected in other geographic areas with primary cases having travel connections to the Arabian Peninsula: in Europe (United Kingdom, Germany, France, Italy, Greece and the Netherlands), in Africa (Tunisia and Algeria), in Asia (Malaysia and Philippines) and in the Americas (USA).
Animal hosts
Dromedary camels: There is growing serological and molecular evidence that the dromedary camel (Camelus dromedarius) is a host species for the MERS-CoV and that circulation of MERS-CoV or MERS-like CoV in dromedaries in Africa and the Arabian Peninsula were occurring well before 2012 [10]. The presence of MERS-CoV-neutralising antibodies in dromedaries has been reported in Saudi Arabia [11,12], United Arab Emirates [13,14], Oman [10], the Canary Islands of Spain [15] in Jordan [16], Egypt [17,18], Qatar [19], Nigeria, Tunisia and Ethiopia [10].
Bats: A short RNA fragment of the conserved viral polymerase region identical to MERS-CoV has been identified in Taphozous perforates bats, but these findings might be unreliable and need to be confirmed [20].
Other animals: In some countries of the Arabian Peninsula goats, cattle, sheep, water buffalo, swine, chicken and wild birds have been tested for antibodies to MERS-CoV, with no positive results [16,21].
MERS-CoV remains viable at 48 hours at 20 °C and 40% relative humidity, comparable to an indoor environment on plastic and metal surfaces. The virions are sensitive to heat, lipid solvents, non-ionic detergents, oxidising agents and ultraviolet light[22]. In aerosol experiments, MERS-CoV retains most of its viability at 20 °C and 40% relative humidity. Viability decreases at higher temperatures or higher levels of relative humidity[22]. In unpasteurised camel milk, MERS-CoV remains infectious beyond 72 hours after introduction to the milk but infectious viruses could not be found after pasteurisation [23].
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Data suggest that the clinical presentation of MERS-CoV infection ranges from asymptomatic to very severe pneumonia with acute respiratory distress syndrome (ARDS), septic shock and multi-organ failure resulting in death. At least two cases had a consumptive coagulopathy during the course of their illness. The clinical course is more severe in immunocompromised patients and more likely to be mild in individuals without underlying medical conditions [24,25]. Although the majority of the cases are aged 40 years and above, cases have also been detected among children. Most cases of childhood MERS-CoV infection appear to be asymptomatic and tested positive during contact investigation of older patients. Severe disease can occur in children with underlying conditions [25].
Clinical symptoms, laboratory investigations, and imaging finding of MERS-CoV are similar to those noted for other community-acquired respiratory-tract infections [26-29].
Typically, the disease starts with fever and cough [26,28,30,31], chills, sore throat, myalgia and arthralgia [26,27,31] followed by dyspnoea [26,27,31], and rapidly progresses to pneumonia, often requiring ventilatory and other organ support. Nearly all symptomatic patients presented with respiratory symptoms; however, one immunocompromised patient was initially admitted to hospital with fever, chills and diarrhoea and later found to have pneumonia [28]. At least one-third of patients also had gastrointestinal symptoms, such as abdominal pain, vomiting and diarrhoea [26-28,31]. Almost half of the patients developed pneumonia, and a lower percentage developed ARDS.
Chest radiograph findings vary but are consistent with viral pneumonitis and ARDS: bilateral hilar infiltration, uni- or bilateral patchy densities or infiltrates, segmented or lobar opacities, ground glass appearance, and small pleural effusions have been described. Lower lobes tend to be affected more than upper lobes early in the course of illness; radiographic appearance progresses rapidly. Computed tomographic scans have shown interstitial infiltrates and consolidation compatible with ARDS in severe cases. In some severe cases, renal failure developed concurrently with respiratory failure.
Common laboratory findings include leucopoenia, particularly lymphopaenia [1,28,29,31]. Reports from a few cases found viral RNA in blood [28], urine [32] and stools [32] but at much lower viral loads than in the respiratory tract.
Co-infection with other respiratory viruses (e.g. parainfluenza, rhinovirus, influenza A(H1N1)pdm09, herpes simplex, influenza B) has been reported in some patients and secondary nosocomally acquired bacterial infections (Klebsiella pneumoniae, Staphylococcus aureus, Acinetobacter sp., Candida sp.) have been reported in patients who received mechanical ventilation [1,30,32].
Case–fatality ratio (CFR) reported so far has been around 40%, with probability of death rising with increasing age or co-morbidity with a medical disorder [26]. Secondary cases, including among healthcare workers, appear to have a lower CFR. Long-term sequelae of patients who recover from acute MERS are not yet known and need to be defined [26].
A second trimester stillbirth, observed in the context of an outbreak, occurred in Jordan in April 2012 in a pregnant woman during the course of an acute respiratory illness attributed to MERS-CoV on the basis of exposure history and positive results of MERS-CoV serologic testing. Although the association between MERS-CoV in this case is only possible because of the retrospective nature of this finding, this is the only information published on the possible impact of MERS-CoV infections on pregnancy outcome. The authors suggest that MERS-CoV infection may pose serious health risks to both foetus and mother, as it has been observed during the SARS-CoV epidemic and influenza A(H1N1) pandemic [33].
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Many uncertainties still exist on the source of MERS-CoV and on the mode of transmission. This is typical of an emerging disease where there are often simultaneous possibilities, including environmental, animal and human exposures.
The continued detection of new MERS-CoV cases, the low estimated basic reproduction number of the infection (R0), and the detection of multiple distinct MERS-CoV genotypes suggest the existence of a persistent possible zoonotic source [34]. This is corroborated by the growing serological and molecular evidence that dromedary camels (Camelus dromedarius) are a host species for MERS-CoV.
By August 2014, the evidence is accumulating that the dromedary camel is a host species for MERS-CoV and that camels play an important role in the transmission to humans. Serological studies in dromedary camels in Jordan, Oman, Qatar, Saudi Arabia and the United Arab Emirates have shown high rates of antibodies against MERS-CoV, indicating widespread circulation of the virus in the Arabian Peninsula, even before the evidence of human infection [11,13]. Antibodies against MERS-CoV have been detected also in dromedary camels in Egypt [17], Ethiopia [10], Kenya [35], Nigeria [10], Tunisia [10], and the Canary Islands (Spain; some originating from Morocco) [15] suggesting that the virus could also be geographically widespread in these animals on the African continent [10].
The hypothesis that dromedary camels are hosts of MERS CoV has been proven by the viral RNA detection in different specimens collected from these animals in Qatar, Saudi Arabia, Oman and Egypt and the isolation of the virus from nasal and faecal samples [11,17,19,36,37]. MERS-CoV RNA has also been detected in the milk of camels actively shedding the virus. Whether infected camels excrete MERS-CoV directly into the milk or the milk is cross-contaminated during milking is unclear [38]. Infection in dromedary camels has been reported to be either asymptomatic or associated with only mild respiratory signs with nasal discharge [11,19,39]. A prospective study of two camel herds in Saudi Arabia from November 2013 to February 2014 showed that acute MERS-CoV infections resulted in increased anti-MERS-CoV titres, that very young animals ( less than one month old) were also infected and that reinfection of animals also appeared to occur, indicating that neither maternal antibodies nor pre-existing antibodies are fully protective. There was no evidence of prolonged virus shedding or viraemia among the tested animals[40].
Although previous studies on the presence of MERS-CoV antibodies in abattoir workers in Saudi Arabia (from Jeddah and Makkah, sampled in October 2012) and in Egypt (June–December 2013) and the evidence of circulation of the virus in camels for decades suggested that the virus is not easily transmitted from camels to humans [17,41], evidence on the role of dromedary camels as a potential reservoir of MERS-CoV and the direct transmission of the virus from infected camels to humans are accumulating.
Phylogenetic analyses of camel-derived MERS-CoV indicate that sequences cluster independently from each other, but together with the human-derived MERS-CoV sequences from the same geographical area [11,17,19,37,40]. Two investigations, one in Qatar and one in Saudi Arabia, reported evidence for the direct cross-species transmission of MERS-CoV from infected camels to their owner [19,36]. Also, preliminary results from recent studies in Qatar indicate that people handling or working with camels are at increased risk of infection with MERS-CoV compared with people who do not have contact with camels [42,43].
The exact routes of transmission among camels and from camels to humans are still not clear. Droplet contact or fomite transmission may be involved. Many of the publications document high viral loads in nasal swab samples from camels [11][37][40], in some studies also in conjunctival swabs [37]. The recent detection of MERS-CoV RNA in camel milk suggests a potential food-borne transmission of the virus by consuming raw milk, a traditional behaviour in Arabic culture [38]. A recent study published by Azhar EI et al. reported the isolation of the virus in an air sample collected in a camel barn involved in a possible camel-to-human outbreak, warranting further investigations for the possible airborne transmission of MERS-CoV [44]. MERS-CoV virus or RNA has not been detected in camel urine, although it is unclear whether such sampling has taken place in any study. The shedding in urine among humans makes it plausible that this also applies to camels. Therefore, taking into account the occasional use of camel urine as a traditional medicine in Arabic culture, the possibility that urine may be a source of infection cannot be disregarded [45]. Incubation period for possible primary zoonotic transmission is unknown.
Camel farming has progressively changed in Saudi Arabia over the last ten years with an increased number of farms near cities [46]. Intensive camel farming could be at the origin of an increased zoonotic risk. A good understanding of the epidemiology of camels (e.g. seasonal calving periods and diarrhoeal outbreaks) is needed to fully assess the zoonotic risk. Many gaps remain in our knowledge of the epidemiology of coronavirus infections in dromedary camels, including exact contact patterns with humans, both in the population generally and in MERS cases.
The transmission of the virus from person to person has been documented in several human clusters (i.e. two or more persons with onset of symptoms within the same 14-day period, and who are associated with a specific setting [47]) in healthcare facilities, households and workplace, both in the Middle East and in Europe [27-31,48-52].
Based on information related to the first 77 cases, the basic reproduction number of the infection (R0) was estimated to be 0.69 (95% CI: 0.50–0.92) at the time [25], indicating a low pandemic potential [26]. A later analysis, integrating information from the countries of the Middle East and from imported cases to newly affected countries estimated an R0 of 0.50 (95% CI: 0.30–0.80) [53],27]. An investigation of community transmission among household contacts of 26 clusters with 280 contacts over six months in 2013 showed nine positive cases by serology and PCR revealing an R0 of 0.35 (Memish, personal communication).
The median incubation period for human-to-human secondary cases is estimated to be just over five days, but could be as long as two weeks (median 5.2 days (95% CI: 1.9 –14.7) [27]; 5.5 (95% CI: 3.6–10.2) [54]).
Nosocomial transmission has been a hallmark of MERS-CoV, both in the Middle East and in Europe [27,28,55], and also caused an upsurge of cases during spring 2014 in Jeddah, Saudi Arabia and Al Ain, UAE [56]. Outbreaks in healthcare settings involved hospitalised patients, healthcare workers and family members [27]. Asymptomatic and mildly symptomatic secondary cases have been identified. In hospitals, transmission has been documented in haemodialysis units, intensive care units and on medical wards [27]. Systematic and strict implementation of infection prevention and control measures in reported clusters in healthcare settings has appeared to limit onward transmission to healthcare workers and hospitalised patients [27,28,57].
Current evidence from contact tracing suggests that transmission did not extend beyond close contacts into the community [58]. Among clusters around exported cases travelling to France, the UK, Italy, Germany and Tunisia from the Middle East, transmission to close contacts has been limited [28,48,51,52,57], and secondary attack rates among family members of patients in other clusters appear to be low [27,29,31,52,59].
In humans, MERS-CoV virus can be detected with higher viral load and longer duration in the lower respiratory tract than in the upper respiratory tract, and has been detected also in faeces, serum, urine and blood samples [28,30,32,60]. However, very limited data are available on the duration of respiratory and extrapulmonary MERS-CoV shedding. In a human case viral RNA was detected in blood from the 13th to the 30th day after onset of illness, virus shedding in urine has been observed up to 30 days, in oronasal swabs up to 22 days and from tracheal swabs up to 30 days [60]. In another study human case virus shedding was detected in stools up to 16 days [32].
MERS-CoV survived better than A(H1N1) viruses on inanimate surfaces and it has the ability to remain viable in aerosol [22]. Recently the virus was isolated in an air sample collected in a camel barn [44]. These findings suggest that the virus is likely to be transmitted by direct contact and via fomites and is possibly airborne.
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WHO provides recommendations for laboratory testing for MERS-CoV. These are based on, and updated according to, the latest scientific knowledge. The most recent recommendations can be found on the WHO Global Alert and Response webpage for coronavirus.
Both upper and lower respiratory tract specimens should be collected. Lower respiratory tract specimens, such as bronchoalveolar lavage, sputum and tracheal aspirates contain the highest viral loads and are to be preferred. If resources permit, further samples from faeces and urine should also be collected and repeated sampling is highly recommended to gather further evidence on viral shedding and infectious periods [61].
Appropriate handling of specimens during collection and transport is important [62].
Currently, confirmation of cases according to WHO standards is performed with detection of viral RNA by real-time PCR targeting upstream of the MRS-CoV E protein (upE) and then a secondary PCR assay targeting open reading frame (ORF) 1a or 1b. A negative secondary PCR result would require further nucleotide sequencing of the viral RNA. Likewise, as an alternative to the secondary PCR assay, sequencing of the viral RNA together with a positive upE test can confirm a case. Target sites suitable for sequencing include the RNA-dependent RNA polymerase (RdRp) and (N) genes [61].
Serology can be used to detect antibodies in patients or contacts when the direct detection (molecular methods) of MERS-CoV is negative in suitable specimens, as well as for human and animal surveys. However, interpretation of MERS-CoV serological results can be hampered by the widespread circulation of other human coronaviruses such as HCoV-OC43, HCoV-HKU1, HCoV-NL63, and HCoV-229E. Different screening assays are used such as indirect immunofluorescence assay (IFA), ELISA, western blot, protein microarrays using the whole virus or recombinant spike and nucleocapsid proteins or a soluble S1 subunit of spike protein. A gold-standard neutralisation test should be used for confirmation (i.e. plaque reduction neutralisation test or micro neutralisation test or using pseudoparticle virus) [63]. Serological testing has confirmed human cases in Germany and asymptomatic infection in the US. In Germany, two cases tested using IFA had high titres of antibodies and this was also confirmed by microarray testing and neutralisation tests [32,48,64]. The possibility of confirming a case by serology, without nucleotide detection, is currently under discussion. In this case, paired serum samples need to be taken and show seroconversion by demonstrable positivity in a screening assay (e.g. ELISA or IFA) with confirmation by a neutralisation assay. Without confirmation using only a neutralisation assay, the case will remain probable.
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The most recent WHO case definitions for MERS-CoV and surveillance guidance can be found on the WHO Global Alert and Response webpage for coronavirus.
All confirmed or possible cases diagnosed in the EU/EEA should immediately be reported by the national authorities to the Early Warning and Response System (EWRS) and to WHO under the International Health Regulations (IHR) (2005).
The WHO surveillance recommendations provide guidance on who should be tested for MERS-CoV, based on the clinical picture and possible exposure patterns.
The WHO advice on home care for patients with MERS-CoV infection presenting with mild symptoms and management of contacts is targeted towards public health and infection control professionals, health managers and healthcare workers. It states that evidence of transmission from mild cases is limited and that currently there is no evidence of transmission from asymptomatic cases.
Confirmed and probable symptomatic cases should be admitted to hospital whenever possible, but if inpatient care is unavailable or unsafe, or if hospitalisation is refused, home care of mild cases in younger people without underlying conditions (e.g. chronic heart, kidney or lung disease, diabetes, immunosuppression, and blood diseases) needs to be considered. If home care is chosen, the patient needs to remain under close medical observation. Contact with the patient should be limited as much as possible, and caregivers should stay in a different room or keep a distance of at least one meter from cases. Strict hand and respiratory hygiene is stressed, and all exposed materials should be disposed of appropriately. Protective equipment should be used whenever possible. A recent article documented the relative stability of MERS-CoV in indoor conditions. MERS-CoV was found to be more stable than influenza A(H1N1)pdm and remained viable for up to 48 hours on plastic and metal surfaces[22]. Therefore, home environments should ensure appropriate environmental cleaning.
Discussions are currently underway on revising guidance for appropriate management of mild or asymptomatic cases, based on recent developments.
A close contact is defined as a healthcare worker or family member providing direct patient care or anyone who had prolonged (>15 minutes) face-to-face contact with a probable or confirmed symptomatic case in any closed setting. Quarantine or isolation for asymptomatic contacts is not recommended but all close contacts of probable and confirmed MERS-CoV cases should be followed-up and monitored for symptoms until 14 days after the last exposure. Close contacts should have a baseline serum sample collected and stored, which can be used for comparison of paired sera if required later. They should immediately seek medical attention if they develop symptoms such as fever, respiratory problems (including coughing and shortness of breath) or diarrhoea.
Although no cases of infection with MERS-CoV on board aircraft have been documented, it is advisable for countries to trace contacts of confirmed MERS cases on flights in accordance with the guidelines for SARS contact tracing in RAGIDA. This should be done regardless of flight time. Priority for contact tracing efforts should be given to:
• passengers seated in the same row as the case
• passengers seated two rows in front or behind the case
• all crew members
• passengers providing care for the case
• passengers having had >15 minutes of face-to-face contact with the case
• passengers having had contact with respiratory secretions of the case
• passengers living in the same household as the case.
Depending on the clinical presentation of the case during the flight and feasibility, Member State officials may consider extending the tracing of contacts beyond three rows to possibly include all passengers and crew members. If firm evidence of on-board MERS-CoV transmission is lacking, efforts should be made to undertake extensive contact tracing in order to inform future public health decisions. If a crew member is the index case and if all passengers cannot be contacted, efforts should concentrate on passengers seated in the area where the crew member was working during the flight. In addition, all other members of the crew should be traced.
If a passenger is suspected of having MERS-CoV infection during a flight, the potentially infectious passenger should – as with any other respiratory infection – be isolated and provided with a surgical face mask. Flight attendants should follow the IATA guidelines for infection control. Captains should radio ahead to the destination airport, informing officials of a suspected MERS-CoV case on board (Article 28 of the International Health Regulations 2005). Passengers should provide identification and contact details (locator cards) to the health authorities within 14 days of the flight (in order to facilitate contact tracing).
High-quality supportive care should be provided to all patients diagnosed with MERS-CoV, tailored to their individual conditions. A decision support tool for treatment of MERS was published by ISARIC (International Severe Acute Respiratory and Emerging Infection Consortium) on 29 July 2013 [65]and updated with Public Health England in July 2014 [66]. This reviews the available evidence on treatment of MERS patients and is largely based on the experience of treating SARS.
Several treatment options, where benefits are likely to exceed risks, are identified in the most recently updated guidance. In particular ISARIC considers that convalescent plasma, interferons, lopinavir and mono- or polyclonal antibodies would all likely have a beneficial risk–benefit profile [66]. However, all of these options remain investigational and should only be used in settings of formal observational studies or controlled intervention trials. ISARIC has published standardised protocols to aid such studies [66].
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For up-to-date epidemiological information about MERS-CoV, please visit our news and epidemiological updates page.
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People who may be at increased risk for MERS-CoV infection are: recent travellers from the Arabian Peninsula, close contacts of an ill traveller from the Arabian Peninsula, close contacts of a confirmed case of MERS, healthcare personnel not using recommended infection control precautions, people with exposure to camels [42].
In response to the MERS outbreak, Saudi Arabia recommended that persons with conditions placing them at risk of infection or severe outcomes of MERS should postpone their participation in the annual Hajj pilgrimage in 2013 and 2014.
No vaccine or prophylactic therapy is available for the prevention of MERS.
Infection control in healthcare settings
According to international WHO guidance [67], the prevention and control of transmission in healthcare settings requires the implementation of control measures, organised hierarchically according to their effectiveness in the form of administrative measures, engineering/environmental measures and the use of personal protective equipment (PPE).
WHO recommends that probable and confirmed cases requiring admission are admitted in adequately ventilated single rooms or airborne precaution rooms. Healthcare workers caring for probable or confirmed cases of MERS-CoV infection should apply standard precautions (including hand hygiene and use of PPE to avoid direct contact with patients’ blood, bodily fluids and secretions) and in addition, contact and droplet precautions (medical mask, eye protection – goggles or a face shield – gown and gloves).
For aerosol-generating procedures, including airway management, such as tracheal intubation, broncho-alveolar lavage and manual ventilation, given the MERS-CoV viability in experimentally aerosolised particles[22], airborne precautions are recommended. The procedure should be performed in an adequately ventilated room with the number of persons in the room limited to a minimum.
All persons present should wear:
• a well-fitted FFP2 or FFP3 respirator
• tight-fitting eye protection
• gloves and a long-sleeved impermeable protective gown.
Further information on infection control can be obtained from the WHO interim guidance document [67].
All specimens collected for laboratory investigation should be regarded as potentially infectious, and healthcare workers who transport clinical specimens should adhere rigorously to standard precautions to minimise the possibility of exposure to pathogens. Additional references are available from WHO [62] and the European Committee for Standardisation.
Safety criteria for prospective donors presenting acute respiratory symptoms are sufficient to identify symptomatic MERS cases residing in or returning from affected countries and exclude them from the donation of blood, cells and tissues [68,69]. Organ donors should be assessed individually in combination with the recipient, taking into account the current epidemiological situation. However, the possibility of asymptomatic viraemia and potential transmission through transfusion and transplantation cannot be excluded.
Nevertheless, the absence of reported transmission through blood transfusion or transplantation and experience with related SARS coronavirus viraemia, which seemed largely confined to the symptomatic patients, suggest that the current risk of donor-derived MERS CoV transmission is very low. Thus specific deferrals of donors returning from affected countries are not considered necessary at this stage of the outbreak.
In any case, travellers returning from Saudi Arabia and Yemen are temporarily deferred from blood donation due to malaria endemicity in those countries. The Netherlands applies universal deferral from blood donation for 28 days of all travellers abroad and France introduced deferral for 28 days of prospective blood donors returning from the Arabian Peninsula and neighbouring countries in 2013.
After proceeding to a science-based evaluation, an ad hoc expert group convened by the World Organisation for Animal Health (OIE) concluded that MERS-CoV in camels did not meet the criteria for inclusion as an OIE listed disease, but, because of its public health implications and zoonotic potential, infection in animals must be reported to the OIE as an emerging disease [70].
Introduction of live ungulates, including camels, their fresh meat and dairy products, to Europe was already well regulated.
According to Regulation (EU) No 206/2010, laying down introduction requirements for live ungulates and their fresh meat, no importation into the EU of any live ungulate (including dromedaries) and their fresh meat is allowed from the Arabic Peninsula [71]. Importation to the EU of dairy products derived from raw camel milk is authorised only after adequate heat treatment of the dairy product or of the raw milk as stated in the Regulation (EU) No 605/2010 [72].
Also, as stated in Commission Regulation (EC) No 206/2009, personal consignments containing meat, milk or their products are not allowed to be introduced in Europe from the Arabic Peninsula, nor from Africa, by post or carried in the baggage of travellers, unless specifically authorised and certified as being eligible for EU entry [73].
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Neither the EU nor WHO recommends any specific travel restrictions, but they do highlight the importance of possible actions that travellers can take to prevent being infected [74].
In addition to generally recommended hygiene measures, and considering the growing evidence of camels being a host of MERS CoV, WHO has posted a general precaution for anyone visiting farms, markets, barns, or other places where animals are present. Travellers should practice general hygiene measures, including regular hand washing before and after touching animals, and avoid contact with sick animals. Travellers should also avoid consumption of raw or undercooked animal products [42].
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