South Korean MERS outbreak likely to spread, health officials say

A MERS outbreak in South Korea — the largest outside Saudi Arabia, where the disease first emerged in 2012 — is likely to grow, the World Health Organization said Tuesday.

MERS, or Middle East Respiratory Syndrome, has infected at least 25 people in South Korea and killed two, according to the World Health Organization.

Doctors have diagnosed five new cases not yet confirmed by the WHO, bringing the total to 30 cases, said Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota, who is in contact with South Korean doctors who are treating the patients.

South Korean officials have isolated 680 people to limit the spread of the disease, which spreads when sick people cough.

There have been at least 1,154 lab-confirmed cases of MERS worldwide since 2012, along with 431 deaths — a mortality rate of 37%.

MERS belongs to the same family of viruses as SARS, or Severe Acute Respiratory Syndrome, which was identified in 2003. Symptoms include fever, cough and shortness of breath, according to the Centers for Disease Control and Prevention.

The first MERS case in South Korea, confirmed May 20, was in a 68-year-old man who had traveled to four Middle Eastern countries. He developed symptoms May 11 and sought care at two outpatient clinics and two hospitals, the WHO said.

Doctors didn't isolate the man because he didn't report exposure to MERS, the WHO said. He was exposed to a number of medical staff and hospital patients, as well as their family members and visitors. Health officials are seeking more information about how he was exposed during his Middle Eastern travels, the WHO said.

The patient infected some patients in the same room, as well as others on the same ward of the hospitals. Some patients became infected after being exposed to the man for as little as five minutes, the WHO said.

Other patients may have spread the virus at other hospitals before they were diagnosed.

The first MERS patient in South Korea shared a hospital ward with a 35-year-old man whose son had tuberculosis and who was taking medication to prevent infection. That man developed a fever after being discharged. He visited two hospitals and was given antibiotics by staff who probably assumed his symptoms were caused by tuberculosis, said Daniel Lucey, an adjunct professor of microbiology and immunology at Georgetown University Medical Center. That man then visited the hospital again, where he was isolated.

Another man infected with MERS in South Korea traveled to China on May 26, against his doctor's orders, and was diagnosed a hospital in that country three days later. The man had symptoms of MERS during his travel, the WHO said.

South Korea's Ministry of Health confirmed that there have been three generations of MERS spread — from the initial patient to a second patient and then to a third patient with no contact with the original patient.

Given how many people were exposed, "further cases can be expected," the WHO said in a statement. People are more likely to spread the disease when they are very sick and coughing more, Osterholm said.

The first MERS case in the United States, a health professional who had traveled to Saudi Arabia, was diagnosed in 2014, according to the Centers for Disease Control and Prevention.

Doctors have long known that coronaviruses such as MERS spread easily in hospitals, Osterholm said. Hospitals helped to spread the SARS outbreak in Toronto in 2003, as sick patients waited in crowded emergency departments, Osterholm said.

The current South Korean outbreak underscores the need to develop a vaccine against MERS, said Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine in Houston.

There's a lot that doctors don't know about coronaviruses, such as why some people appear so much more contagious than others. During the 2003 SARS outbreak, doctors called highly infectious people "super spreaders" because they infected dozens of people. Other patients, however, never infect anyone. "These people may have more of the virus, or their coughs may be more efficient at spreading it," Osterholm said.

Osterholm notes that it's difficult to tell if the South Korean outbreak is spreading any more quickly than usual. In past outbreaks in Saudi Arabia, world health officials often received information long after patients had been treated.

South Korean officials have been quick to notify international authorities of new developments, allowing people to follow the outbreak "in real time," Osterholm said.

"There is a lot more transparency here than on the Arabian peninsula," Osterholm said.

Because South Korea has an advanced medical system, it is better positioned to contain the MERS outbreak than developing nations, Osterholm said.

"The fact that MERS has spread around the world is not surprising," Osterholm said. "The question is, 'Where is it going to spread to next?' It could very easily come to America. Very easily. Any flight could contain someone who was infected in the Middle East."