Middle East Respiratory Syndrome (MERS) or Middle East Respiratory Syndrome Coronavirus (MERS-CoV) is an illness caused by coronaviruses, a large family of viruses causing diseases ranging in severity from the common cold to Severe Acute Respiratory Syndrome (SARS).
Health officials first reported the disease in Saudi Arabia in September 2012. Globally, since September 2012, laboratory-confirmed cases of infection with MERS-CoV, have been identified across the Arabian Peninsula, Asia, Europe, Africa, and the USA. Patients reported outside the Middle East all had a history of recent travel to the Arabian Peninsula or had close contact with a primary case. To date only two patients in the U.S. have ever tested positive for MERS-CoV infection—both in May 2014.
All modes of transmission are not well understood but MERS-CoV has spread from ill people to others through close contact, such as caring for or living with an infected person.
Most people with MERS-CoV infection present with symptoms of fever, cough, and shortness of breath that may progress to severe acute respiratory illness. Some people experience gastrointestinal symptoms including diarrhea and nausea/vomiting. Severe complications of MERS include pneumonia and kidney failure. Among confirmed MERS-CoV cases reported to date, the case fatality proportion is approximately 35% (Centers for Disease Control and Prevention [CDC], 2015). Most of the people who died had an underlying medical condition. Some individuals experienced only mild cold-like symptoms, and asymptomatic cases have been detected.
The incubation period for MERS (the time between exposed to MERS-CoV and the start of symptoms) is usually about 5 or 6 days, but can range from 2-14 days.
Transmission from Animals to Humans
MERS‐CoV is a zoonotic virus (passed between animals and humans). It is believed that humans can be infected through direct contact with infected dromedary camels in the Middle East or their milk, urine or other body fluids.
Transmission from Person to Person
MERS-CoV is thought to spread through respiratory secretions of infected persons (e.g. coughing). The virus does not appear to pass easily from person to person unless there is close contact such as providing care to or living with an infected person. Spread has occurred in health care settings but has not been documented in community settings.
Information for General Public
Information for Healthcare Professionals
Healthcare providers are advised to be aware of patients who should be evaluated for MERS-CoV infection based on the current epidemiology of the disease, using clinical judgment and as information about modes of transmission of MERS-CoV and the clinical presentation continues to evolve.
- CDC's recommendations for Healthcare Professionals
- CDC's case definitions for patient under investigation (PUI), confirmed case, and probable case
- CDC's guidance for clinical evaluation, management and treatment
- WHO guidelines for investigation of cases of human infection with MERS (July 2013)
- WHO guidelines for clinical management
- CDC's infection prevention and control recommendations for hospitalized patients with MERS-CoV (June, 2015)
- WHO guidelines for infection prevention and control
- CDC's checklists for providers and healthcare facilities that identify key actions to be taken now to enhance preparedness for MERS-CoV infection control
Information for Laboratories
Laboratories are recommended to coordinate with CDC for specimen testing since widely available diagnostic tests are not suitable.
- CDC's Guidelines for Collecting, Handling, and Testing Clinical Specimens from Patients Under Investigation (PUIs) for MERS-CoV
- CDC's Laboratory Biosafety Guidelines for Handling and Processing Specimens Associated with MERS-CoV
- CDC Laboratory Testing for MERS-CoV
- WHO's guidance on laboratory testing for MERS (Sep 2013)