Fourth patient dies of MERS in South Korea

A fourth patient has died of MERS, or Middle East Respiratory Syndrome, in the largest outbreak outside of Saudi Arabia.

Six additional patients have been diagnosed, bringing the total infected to 41, said Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota, who has been in contact with South Korean doctors.

South Korea has quarantined more than 1,600 people as of Thursday, according to the Yonhap News Agency, the largest in the country. South Korea also has closed hundreds of schools, amid protests charging that the government has been too slow to contain the virus, which has killed more than 400 people worldwide since 2012.

City officials from Seoul announced Thursday that a medical doctor was in contact with more than 1,000 people while he was infected with MERS, according to Yonhap. The doctor, who works for a hospital in Seoul, attended several large events after he was ordered into quarantine.

Doctors don't know exactly how long people who are infected with MERS are contagious before they develop symptoms, said Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine in Houston.

But the Centers for Disease Control and Prevention recommends that people who have been exposed to MERS in the past 14 days should see a doctor, suggesting the incubation period is two weeks.

Quarantining people potentially exposed to MERS is a sound strategy to prevent spread of the virus, said Robert Murphy, director of the Center for Global Health at Northwestern University in Chicago.

Careful infection control procedures at hospitals also can halt the spread of MERS "pretty quickly," Murphy said. As in other MERS outbreaks, those infected in South Korea were exposed in the hospital by a man who had traveled to the Middle East. That initial patient exposed doctors, nurses, patients and their visitors before hospital staff tested him for MERS.

Doctors in South Korea should immediately test patients with fever or cough, isolating anyone who tests positive for the virus, Murphy said. Health officials also should isolate anyone who's had contact with an infected patient.

The country's first MERS patient, diagnosed May 20, reportedly didn't tell medical staff he had traveled to the Middle East. He visited two outpatient clinics and two hospitals before he was diagnosed and isolated, according to the World Health Organization.

Health professionals should ask all patients whether they have traveled outside their home country in the past month, Osterholm said. That basic question can help doctors quickly diagnose not just MERS, but Ebola, malaria or other infectious diseases.

Closing schools might have little effect on the spread of MERS, Osterholm said.

Although scientists don't fully understand how MERS spread, cases in South Korea and elsewhere have been concentrated at hospitals and health clinics as undiagnosed patients spread the disease, Osterholm said. Unlike the flu or cold viruses, MERS has never circulated widely in the community.

"Closing the schools is totally unnecessary," Osterholm said. "The real focus has to be preventing transmission in health-care settings."

In the past, people have become infected with MERS only after very close contact, such as caring for a sick family member at home. In the South Korean outbreak, however, some patients have become infected after being exposed for as few as five minutes, according to the WHO.

SARS, a close cousin of MERS that emerged in 2002, also primarily infected caregivers, health professionals or their contacts, Osterholm. SARS, short for Severe Acute Respiratory Syndrome, infected nearly 8,100, killing about 10% of its patients, and then disappeared almost as suddenly as it surfaced, according to the WHO.

There's no evidence the MERS virus has mutated to become more contagious, said Gregory Gray, a physician and professor of global health and infectious disease at Duke University's Global Health Institute and School of Medicine, in a statement.

Unless tests show MERS is mutating in dangerous ways, "school closures and the subsequent public panic are likely to do more harm than good," Gray said. "Measures that people will likely take — such as buying masks that could potentially be used for more dire medical emergencies — are out of balance with the actual risk."