BEIJING, June 12 -- China's aviation regulator ordered all airline companies to strengthen the prevention and control of the Middle East Respiratory Syndrome (MERS) for flights between China and the Republic of Korea (ROK) on Friday.

Airline companies operating flights between the two countries should increase flight crew's awareness of the disease, intensify disinfection of airplanes and act quickly in treatment of suspected MERS cases, said a statement of the Civil Aviation Administration of China (CAAC).

On May 29, a man from the ROK tested positive for MERS while in southeastern Guangdong Province.

All 75 people in Guangdong who had been in close contact with the man have been released from quarantine, local health authorities announced on Thursday.

MERS is a respiratory illness caused by a coronavirus, similar to Severe Acute Respiratory Syndrome (SARS). The first human case was recorded in Saudi Arabia in 2012. There is no vaccine or treatment for the disease, which has a fatality rate of about 40 percent.