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  • MERS Clinical Update from the IDSA

    CDC HAN Advisory, June 11, 2015
    Updated guidance on the evaluation of patients for MERS-CoV infection. Revised in lightof the current situation in the Republic of Korea

    (Updated 5/19/2014) An update on the current situation regarding Middle East Respiratory Syndrome (MERS) with links to credible source materials of particular relevance for ID specialists.


    In 2012 a novel human coronavirus (subsequently designated MERS-CoV) was reported as the etiology of severe community-acquired pneumonia1. Since then sporadic cases and asymptomatic infections continued to be detected in countries in the Arabian Peninsula with a few travel-associated cases imported elsewhere. In the past 2 months a notable increase has occurred in the number of cases of MERS-CoV infection reported in countries in or near the Arabian Peninsula, as well as an increase in countries reporting imported cases. This development prompted review on May 13, 2014 by the WHO Emergency Committee which noted no sustained chains of human-to-human transmission, but registered concern about the trend. Two imported cases have now been reported in the US this month2 with an additional secondary case in a contact who seroconverted3.

    Clinical Aspects

    Both upper and lower respiratory tract infection are described. The severity of pneumonia has varied from mild to clinically necessitating hospitalization, ICU management and ventilator support. Kidney failure has developed in some cases. GI symptoms have included nausea, vomiting and diarrhea and may precede respiratory symptoms. Asymptomatic infections have been noted mainly through contact investigations. As of May 16, 2014 WHO has reported 572 laboratory-confirmed cases of which 173 have been fatal4. Health-care workers (HCWs) account for 19% of cases2. For secondary cases of human-to-human transmission the median incubation period was 5 days (range 3-12 days)2.


    In the US at the present time, persons who meet these criteria5 are recommended for testing for MERS-CoV:

    Fever and pneumonia or ARDS with one of the following:

    • Travel in the past 14 days from countries in or near the Arabian Peninsula
    • Close contact with an ill traveler who has fever and acute respiratory illness (not necessarily pneumonia) with the same travel history as above
    • Close contact with a confirmed or probable MERS case ill at the time of contact

    Clusters of severe pneumonia of unknown etiology can be considered for testing for MERS-CoV in conjunction with state health department consultation.

    A real-time RT-PCR assay for MERS-CoV is available in the US through most state health department laboratories. Specimens for rRT-PCR testing include specimens from the upper and lower respiratory tract (e.g. nasopharyngeal swab, sputum, BAL), blood and stool6. If it is within 14 days of symptom onset, multiple specimens should be obtained from different sites and at different intervals from symptom onset for rRT-PCR testing. MERS-CoV viral load and genome yield were higher in specimens of lower respiratory tract origin7. Serology is included if more than 14 days from onset have elapsed. Interpretation of MERS-CoV laboratory results is provided with case definition8.

    Suspected MERS cases can be simultanelously tested for other causative agents of pneumonia as deemed clinically appropriate5. MERS-CoV is not expected to be detected on rapid viral respiratory panels (RVP) commercially available in the US.

    Infection Control and Prevention

    Patients with known or suspected infection with MERS-CoV should have combined standard, contact and airborne precautions9. Gowns, gloves, face shield or goggles for eye protection and N-95 or greater respirator or equivalent level of protection should be worn while caring for the patient. The duration for such precautions is not known. A face mask should be worn by the patient when not in airborne isolation to facilitate source control. HCWs caring for confirmed or suspected cases of MERS-CoV infection should monitor themselves for 14 days after last contact with the patient for any symptoms of acute illness9. HCWs who become symptomatic should not report for work. Those HCWs who were not wearing personal protective equipment (PPE) and were exposed to a confirmed or probable MERS-CoV infected patient should be considered for monitoring and self-quarantine at home9.
    For persons not ill enough to need hospitalization, specifications for monitoring and infection control in the home are provided10.

    Source control at triage for persons with acute respiratory infection is critical to limiting exposures of other patients and health-care personnel. Masks, alcohol hand gel and handwashing facilities with soap and water should be available and systematically deployed in areas where ill patients are initially encountered, e.g. emergency departments, clinics, urgent care centers and provider offices. Patients with acute respiratory illness should be asked about travel to countries in or near the Arabian Peninsula or contact with ill persons with similar travel history. Six cities in North America (Atlanta, Chicago, Los Angeles, New York, Toronto and Washington DC) have been the points of entry historically for the majority of air travelers on flights to the US from Suadi Arabia and United Arab Emirates (UAE) with traveler volumes between 10-30,000 persons in May and June2.


    Although hospitals and medical facilities previously developed pandemic influenza plans, these may not have been reviewed recently or are unfamiliar to newer members of the workforce. In the US, the usual heightened awareness of the winter respiratory illness peak has dwindled as the level of influenza activity has declined. Stockpiles of PPE, alcohol hand sanitizer and other supplies may be more limited than previously due to constrained budgets. These factors should create a sense of urgency to address preparedness in light of the recent increase in MERS-CoV cases.

    ID specialists need to underscore the changing epidemiology of MERS-CoV infections to the administration and core personnel of the facilities in which they work, emphasizing the need to proactively improve readiness. Helpful checklists for MERS preparedness have been developed for providers11 and for healthcare facilities12. These can promote prompt review of facility pandemic influenza plans with guidance from ID specialists on modifications as appropriate for MERS-CoV.


    In the past 2 months, there has been a notable increase in reported cases of MERS-CoV infection and in countries with imported cases, now including the US. The reason(s) for the increase are unclear. To date there has not been sustained human-to-human transmission but because this could change, the situation bears close watching. IDSA members should be aware of these developments, the potential for change, and engage with their medical facility personnel and health departments to promptly focus on preparedness. IDSA will provide additional updates as developments warrant.


    1. Zaki AM, van Boheemen S, Bestebroer TM, et al. Isolation of a novel coronavirus from a man with pneumonia in Saudi Arabia. N Engl J Med 2013;367:1814-20.
    2. CDC. First confirmed cases of MERS-CoV infection in the United States, updated information on the epidemiology of MERS-CoV infection, and guidance for the public, clinicians and public health authorities – May 2014. MMWR (Early release)
    3. CDC. Illinois resident who had contact with Indiana MERS patient tests positive for MERS coronavirus.
    4. WHO. Global Alert and Response – Coronavirus infections.
    5. CDC. Interim guidance for health professionals: patients in the US who should be evaluated for MERS-CoV infection.
    6. CDC. Interim guidelines for collecting, handling and testing clinical specimens from patients under investigation (PUIs) for MERS-CoV – Version 2.
    7. Memish ZA, Al-Tawfiq JA, Makhdoom HQ, et al. Respiratory tract samples, viral load and genome yield in patients with Middle East respiratory syndrome. J Infect Dis 2014
    8. CDC. Middle East Respiratory Syndrome (MERS) Case Definitions
    9. CDC. Interim infection control and prevention recommendations for hospitalized patients with MERS-CoV.
    10. CDC. Interim home care and isolation guidance.
    11. CDC. Healthcare provider preparedness checklist for MERS-CoV.
    12. CDC. Healthcare facility checklist for MERS-CoV.

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