MERS is caused by a virus referred to as "MERS-CoV" from the coronavirus genus; MERS-CoV means Middle East respiratory syndrome coronavirus. The genus coronavirus includes viruses that infect animals, cause the common cold in humans, and caused the 2003 SARS outbreak in China. However, the MERS-CoV virus is different than other coronaviruses, including SARS-CoV, and had never been identified before 2012. MERS-CoV has been detected in camels in several countries but not in other livestock. It has been detected in camel meat, organs, milk and urine; infected camels may not be observably ill.

MERS-CoV is spread from person to person through respiratory droplet secretions. MERS has often infected people caring for a sick (MERS-CoV-infected) individual. Contact with infected body fluids, respiratory secretions, raw or undercooked meat, and unpasteurized dairy products of camels may be other sources of transmission to humans.

MERS-CoV infection should be suspected in travelers who've recently returned from the Arabian Peninsula or neighboring countries with a compatible illness occurring within 10 days of traveling. Health-care workers or contacts of a MERS-infected individual are at risk, as are veterinary, farm, dairy, market, race track, and abattoir workers who handle camels.