Seoul, South Korea (Reuters) — South Korea on Monday (June 1) confirmed the number of people in the country infected with the Middle East Respiratory Syndrome (MERS) virus had risen to 18.

First identified in humans in 2012, MERS is caused by a coronavirus from the same family as the one that triggered China's deadly 2003 outbreak of Severe Acute Respiratory Syndrome (SARS). There is no cure or vaccine.

The first patient was diagnosed on May 20 after a trip to Bahrain, Saudi Arabia and the United Arab Emirates, the health ministry added.

"There are three additional cases, so we confirmed that a total of 18 people have MERS. These three people among the 18 are the same as the other 15 patients, who were infected by the first confirmed case and are linked with one specific hospital," South Korean Director of Public Health Policy, Kwon Jun-wook said.

Chair of Korean Society of Infectious Diseases Kim Woo-joo said five of the 18 were in a serious condition.

"There should be no deaths and tertiary transmissions. However, as Director Kwon says, five people among 18 are in serious condition. They have pneumonia symptoms and have been put on respirators," he said.

South Korean President Park Geun-hye on Sunday (May 31) said a task force to deal with the spread of the virus in the country had been set up.

The United Nations health agency has not recommended the screening of passengers or that travel or trade restrictions be imposed on South Korea due to the outbreak.