Middle East respiratory syndrome (MERS) is a viral illness caused by infection with MERS coronavirus (MERS-CoV), a species belonging to lineage C of the genus Betacoronavirus. It is an emerging cause of severe viral respiratory illness in humans. Illness in humans is acquired by direct or indirect contact with dromedary camels, which data suggest are the natural host and zoonotic source of the virus. Nonsustained human-to-human transmission has occurred among close contacts and in health care settings.

People of all ages have been affected by MERS-CoV, although the median age is about 50 (range <1 year to 99 years of age), with a male predominance. Most patients experience severe acute respiratory syndrome requiring hospitalization. Approximately 36% of patients with MERS have died.

Since the first report of MERS in 2012, more than 2600 cases, including at least 935 deaths, in 27 countries have been reported to the World Health Organization (WHO), with a majority occurring in the Kingdom of Saudi Arabia. An outbreak in South Korea over a 2-month period in 2015 was the largest outside of the Middle East, involving 186 cases, including 38 deaths; the index patient had a recent history of travel to 4 countries in the Middle East and was asymptomatic until his return home, where he sought care at 2 clinics and 2 hospitals.

Patients who have recently traveled to the Middle East and have unexplained fever and/or symptoms of a lower respiratory illness, including cough, dyspnea, weakness, and fatigue, within 14 days of travel should be investigated for MERS-CoV. Less frequent symptoms may include gastrointestinal symptoms such as abdominal pain, vomiting, and/or diarrhea.

The most common risk factors linked to MERS-CoV include residence in or travel to countries in or around the Arabian Peninsula, a history of contact with dromedary camels, a history of raw camel milk consumption, and direct / indirect association with a health care setting. Patient-to-patient nosocomial transmission within the 9- to 12-day incubation period has been described as a risk factor. Also, close physical contact (including residence or visiting) with people who provide care for ill patients increases risk of infection. Tobacco abuse may be a possible underlying factor.

The WHO has reported many cases involving patients with chronic underlying medical conditions (hypertension, diabetes mellitus) or immunosuppression (renal transplantation, chronic corticosteroid use). Asymptomatic cases have been reported, mostly among contacts of laboratory-confirmed cases.

The Centers for Disease Control and Prevention (CDC) does not recommend travel changes because of MERS. Travelers should pay attention to their health during and after a trip in or around the Arabian Peninsula (including Bahrain, Iraq, Iran, Israel / Palestinian territories, Jordan, Kuwait, Lebanon, Oman, Qatar, Saudi Arabia, Yemen, and the United Arab Emirates) and see a physician if any of the symptoms are present during or after travel to these areas.

Related topics: severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (COVID-19)