MERS Coronavirus — An Update

Summary and Comment |
June 12, 2013

MERS Coronavirus — An Update

  1. Stephen G. Baum, MDAU076

A novel coronavirus originating in the Middle East and exported to Europe causes severe respiratory disease with a high case-fatality rate.

  1. Stephen G. Baum, MDAU076

The first report of a novel coronavirus causing human infection on the Arabian Peninsula was received in September 2012. By June 7, 2013, the Middle East respiratory syndrome coronavirus (MERS-CoV) — as is it now known — had caused 55 confirmed cases, all of which were linked to four countries: Saudi Arabia (40 cases), Qatar, Jordan, and the United Arab Emirates. Four additional countries — the U.K., Italy, France, and Tunisia — have reported cases in returning travelers and their close contacts. To date, no cases have been reported in the U.S.

Person-to-person spread in nosocomial environments, both to other patients and to healthcare personnel, has been documented. The median age of patients is 56 years; 72% are female. The incubation period is now estimated to be 9 to 12 days (an increase from the 1–9 days initially described), and the case-fatality rate is 56%.

Because tests of upper respiratory samples have sometimes yielded negative results for patients later confirmed to be infected, testing of lower respiratory tract specimens (e.g., from cough or bronchial washing) with a newly approved polymerase chain reaction assay is recommended.


In new outbreaks, it is common for cases with the shortest incubation period to surface first, and for estimates of incubation periods to increase. Also, it would appear that respiratory symptoms may be mild or even absent at the outset of illness caused by the Middle East respiratory syndrome coronavirus. Clinicians should be alert to the possibility of infection with this pathogen and should contact the CDC if they encounter patients who develop severe acute lower respiratory illness within 14 days after returning from the endemic area — or are close contacts of such individuals. Current information and guidance are available on the CDC's MERS website.

Editor Disclosures at Time of Publication

  • Disclosures for Stephen G. Baum, MD at time of publication Editorial boards Medical Letter


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