Updated Information on the Epidemiology of Middle East Respiratory Syndrome Coronavirus (MERS-CoV) Infection and Guidance for the Public, Clinicians, and Public Health Authorities, 2012–2013

Gayle Langley


Morbidity and Mortality Weekly Report. 2013;62(38):793-796. 

In This Article

CDC Guidance

Evaluating Patients

CDC has changed its guidance to indicate that testing for MERS-CoV and other respiratory pathogens* can be conducted simultaneously and that positive results for another respiratory pathogen should not necessarily preclude testing for MERS-CoV. Health-care providers in the United States should continue to evaluate patients for MERS-CoV infection if they develop fever and pneumonia or acute respiratory distress syndrome (ARDS) within 14 days after traveling from countries in or near the Arabian Peninsula. Providers also should evaluate patients for MERS-CoV infection if they have ARDS or fever and pneumonia, and have had close contact§ with a recent traveler from this area who has fever and acute respiratory illness.

CDC continues to recommend that clusters of patients with severe acute respiratory illness (e.g., fever and pneumonia requiring hospitalization) be evaluated for common respiratory pathogens and reported to local and state public health departments. If the illnesses remain unexplained, particularly if the cluster includes health-care providers, testing for MERS-CoV should be considered, in consultation with state and local health departments. In this situation, testing should be considered even for patients without travel-related exposure. Additional information about CDC's interim guidance regarding who should be evaluated for MERS-CoV infection is available at http://www.cdc.gov/coronavirus/mers/interim-guidance.html.

Case Definitions

Although CDC has not changed the case definition of a confirmed case, confirmatory laboratory testing now requires a positive polymerase chain reaction of at least two, instead of one, specific genomic targets or a single positive target with sequencing of a second. CDC's definition of a probable case has been changed so that identification of another etiology does not exclude a person with an illness meeting this definition from being classified as having a probable case. Additional information about CDC's case definitions is available at http://www.cdc.gov/coronavirus/mers/case-def.html.

Travel Guidance

The peak travel season to Saudi Arabia is July through November, coinciding with the religious pilgrimages of Hajj and Umrah. CDC encourages pilgrims to consider recommendations from the Saudi Arabia Ministry of Health regarding persons who should postpone their pilgrimages this year, including persons aged ≥65 years, children, pregnant women, and persons with chronic diseases, weakened immune systems, or cancer (http://www.moh.gov.sa/en/coronanew/news/pages/news-2013-7-14-001.aspx). WHO advises that persons with preexisting medical conditions consult a health-care provider before deciding whether to make a pilgrimage (http://www.who.int/ith/updates/20130725/en).

CDC continues to recommend that U.S. travelers to countries in or near the Arabian Peninsula protect themselves from respiratory diseases, including MERS-CoV, by washing their hands often and avoiding contact with persons who are ill. If travelers to the region have onset of fever with cough or shortness of breath during their trip or within 14 days of returning to the United States, they should seek medical care. They should tell their health-care provider about their recent travel. More detailed travel recommendations related to MERS-CoV are available at http://wwwnc.cdc.gov/travel/notices/watch/coronavirus-arabian-peninsula.

Infection Control

With multiple health-care–associated clusters identified.[8,10] infection control remains a primary means of preventing and controlling MERS-CoV transmission. CDC has recently made checklists available that highlight key actions that health-care providers and facilities can take to prepare for MERS-CoV patients (http://www.cdc.gov/coronavirus/mers/preparedness/index.html). CDC's infection control guidance has not changed. Standard, contact, and airborne precautions are recommended for management of hospitalized patients with known or suspected MERS-CoV infection.

CDC has determined that federal isolation and quarantine are authorized for MERS-CoV under Executive Order 13295 (http://www.cdc.gov/quarantine/aboutlawsregulationsquarantineisolation.html).** At this time, CDC is not restricting the movement of travelers with respiratory illness (that is not confirmed or probable MERS-CoV infection) arriving from the Arabian Peninsula. However, persons with illness meeting CDC's definition of a confirmed or probable case of MERS-CoV infection should remain in isolation until they are no longer considered to be contagious according to current guidance. Those who do not adhere to isolation requirements, or who intend to travel, may be subject to additional public health measures. CDC does not recommend quarantine of asymptomatic persons who were exposed to confirmed or probable cases. CDC generally recommends that persons with febrile respiratory illness delay travel until their symptoms resolve.

CDC has issued new guidance for care and management of MERS-CoV patients in the home and guidance for close contacts of these patients (http://www.cdc.gov/coronavirus/mers/hcp/home-care.html). Persons who are confirmed, or being evaluated for MERS-CoV infection, and do not require hospitalization for medical reasons should be isolated in their homes as long as the home is deemed suitable for isolation. CDC currently recommends MERS-CoV patients should be isolated at home until public health authorities or a health-care provider determine that they are no longer contagious. Persons who might have been exposed†† to MERS-CoV should be monitored for fever and respiratory symptoms for 14 days after the most recent exposure. Asymptomatic exposed persons do not need to limit their activities outside the home. If persons exposed to MERS-CoV have onset of symptoms, they should contact a health-care provider as soon as possible and follow the precautions for limiting possible exposure of other persons to MERS-CoV.

More detailed MERS-CoV–related interim guidance about patient evaluation, case definitions, travel, and infection control is available at http://www.cdc.gov/coronavirus/mers/index.html. This guidance might change as CDC learns more about the epidemiology of MERS-CoV. CDC will continue to post the most current information and guidance on its MERS-CoV website. State and local health departments with questions should contact the CDC Emergency Operations Center at 770-488-7100.

* Examples of respiratory pathogens causing community-acquired pneumonia include influenza A and B, respiratory syncytial virus, Streptococcus pneumoniae, and Legionella pneumophila.

Countries considered in or near the Arabian Peninsula include Bahrain, Iraq, Iran, Israel, Jordan, Kuwait, Lebanon, Oman, Palestinian Territories, Qatar, Saudi Arabia, Syria, UAE, and Yemen.

§ Close contact is defined as 1) any person who provided care for the patient, including a health-care worker or family member, or had similarly close physical contact; or 2) any person who stayed at the same place (e.g., lived with or visited) as the patient while the patient was ill.

In accordance with WHO guidance for MERS-CoV, a cluster is defined as "two or more persons with onset of symptoms within the same 14-day period who are associated with a specific setting, such as a classroom, workplace, household, extended family, hospital, other residential institution, military barracks, or recreational camp." Information available at http://www.who.int/csr/disease/coronavirus_infections/InterimRevisedSurveillanceRecommendations_nCoVinfection_27Jun13.pdf.

** Severe acute respiratory syndrome (SARS) was added to Executive Order 13295 (http://www.gpo.gov/fdsys/pkg/WCPD-2003-04-07/pdf/WCPD-2003-04-07-Pg408.pdf) in response to the 2003 outbreak. SARS is defined under the executive order as a disease associated with fevers and signs and symptoms of pneumonia or other respiratory illness, transmitted from person-to-person predominantly by the aerosolized or droplet route, and, if spread in the population, would have severe public health consequences. MERS-CoV infection meets these syndromic criteria and therefore meets the criteria for a quarantinable communicable disease. SARS and MERS-CoV infections are caused by different but related coronaviruses.

†† Persons who might have been exposed to MERS-CoV include persons who care for or have close contact with someone who has MERS-CoV infection, persons who recently traveled to countries in or near the Arabian Peninsula, and persons who were identified as a result of a public health investigation of MERS-CoV infection cases.