South Korea’s outbreak of the deadly MERS virus is "large and complex" and more cases should be expected, a team of World Health Organization (WHO) experts said Saturday.

South Korea's outbreak of the deadly MERS virus is "large and complex" and more cases should be expected, a team of World Health Organization (WHO) experts said Saturday.

WHO and South Korean health authorities have conducted a joint mission to review the outbreak of Middle East Respiratory Syndrome (MERS), the largest outside Saudi Arabia.

The outbreak in South Korea has been spreading at an unusually fast pace, with 138 confirmed infections as of Saturday, with the country's first case diagnosed on May 20.

South Korea on Saturday reported the 14th death from the disease and 12 new cases, including that of an ambulance driver who transported a patient infected with the deadly virus.
"Now the outbreak has been large and is complex, more cases should be anticipated", WHO Assistant Director-General for Health Security Keiji Fukuda told journalists.
"And because of this, the government should remain vigilant and should continue its intensified disease surveillance and prevention measures until the outbreak is clearly over".
But he praised South Korean authorities for their strong tracing, monitoring and quarantine measures, backed by expanded laboratory diagnostic testing.
Fukuda said there was a "great deal of anxiety" among Koreans over the outbreak, particularly over whether the virus has mutated to make human-to-human transmission easier.
"Based on available sequencing studies of the genetics of the virus, we do not see any changes that appear to have made the virus itself more transmissible", Fukuda said.
The outbreak is showing epidemiological patterns similar to the one occurring in hospitals in the Middle East, he said.