Middle East respiratory syndrome (MERS) may be a viral respiratory illness caused by a completely unique coronavirus (Middle East respiratory syndrome coronavirus, or MERS?CoV) that was first identified in Saudi Arabia in 2012. Coronaviruses are an outsized family of viruses which will cause diseases starting from the cold to Severe Acute Respiratory Syndrome (SARS). Typical Middle East respiratory syndrome symptoms comprise fever, cough and shortness of breath.

Pneumonia is common, but not always present. Gastrointestinal symptoms, including diarrhoea, have also been reported. Some laboratory-confirmed cases of MERS-CoV infection are reported as asymptomatic, meaning that they are doing not have any clinical symptoms, yet they're positive for MERS-CoV infection following a laboratory test. Most of those asymptomatic cases are detected following aggressive contact tracing of a laboratory-confirmed case. About 35% of reported patients with MERS have deceased.

Although most of human cases of MERS-CoV infections are attributed to human-to-human infections in health care settings, current scientific evidence suggests that dromedary camels are a serious reservoir host for Middle East respiratory syndrome-CoV and an animal source of MERS infection in human beings. However, the precise role of dromedaries in transmission of the virus and therefore the exact route(s) of transmission are unknown.