Deadly MERS spreads in small cluster in South Korea

Thirty people have virus in outbreak, including China’s first case

Monkey cell infected with the virus that causes MERS

INFECTED  The virus that causes Middle East respiratory syndrome, or MERS, (shown in yellow infecting a monkey cell in the lab) has sickened 1,179 people worldwide, including 30 in an outbreak in South Korea. 

NIAID/Flickr (CC BY 2.0

South Korea has closed schools and canceled some public events amid concerns that an outbreak of Middle East respiratory syndrome, known as MERS, could become a pandemic. But officials from the World Health Organization say they expect standard infection-control measures to contain the outbreak. So far, the virus has been known to spread between people mostly inside of hospitals and among family members in close contact with a sick person.

MERS originated in the Middle East and travelers have carried the virus to other countries before, but spread in those places has been limited. Camels and bats may carry the virus and sometimes pass it to humans. Researchers don’t yet understand how the virus is transmitted from animals to people, or from person to person.

The South Korean outbreak started with a man who had traveled to the Middle East in April and early May. He fell ill upon his return to South Korea, and 29 other people, either directly or indirectly connected to him, caught the virus before doctors recognized it as MERS and instituted containment measures. Two have died.

Those infected include family members, as well as patients and health care workers in hospitals where the man was treated. People who contracted the virus from the traveler could have passed it to others. Those “tertiary” cases could indicate that the virus is adapting to spread easily from person to person. Health officials in South Korea have quarantined 1,369 people who had contact with the sick people.

One of the people who got MERS from the traveler then flew to Hong Kong and took a bus to Guangdong, China. Chinese officials have isolated the man and are looking for people he had contact with on his journey.

Researchers have previously documented the spread of the virus in hospitals in Saudi Arabia (SN Online: 6/19/13). This outbreak “feels like Saudi Arabia to me,” says Trish Perl, an infectious disease doctor and epidemiologist at Johns Hopkins University.

More details could help scientists understand why the virus sweeps through hospitals, she says. MERS probably spreads using large mucus droplets that may spray several feet when someone coughs or sneezes. Some medical procedures that help patients breathe may turn droplets carrying the virus into fine mists, or aerosols, that others might inhale, Perl says.

“This disease has shown us that it can be very explosive when you don’t take proper precautions,” she says. But infectious disease containment measures, such as isolating patients and wearing protective garments, can stop outbreaks. 

Tina Hesman Saey is the senior staff writer and reports on molecular biology. She has a Ph.D. in molecular genetics from Washington University in St. Louis and a master’s degree in science journalism from Boston University.

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