Since the Middle East respiratory syndrome coronavirus was first identified in 2012, doctors have struggled to explain how many patients have fallen sick. MERS can cause symptoms including fever, breathing problems and kidney failure. To date, it has infected more than 180 people and killed 79, mostly in the Middle East, though infections have also spread to Europe and northern Africa.

The virus is related to SARS, which killed about 800 people in a global 2003 outbreak. Camels or bats have been suspected as being possible animal reservoirs of MERS but there has been little hard evidence.