Superspreaders spawn Korea MERS outbreak that kills one in five


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People wearing masks stand next near exchange rate signage in Seoul. People wearing masks stand next near exchange rate signage in Seoul.


South Korea’s MERS outbreak was fanned by three “superspreaders” and followed a pattern of transmission similar to the SARS epidemic more than a decade ago, researchers in Hong Kong found.
In the largest outbreak outside the Arabian Peninsula, the Middle East respiratory syndrome coronavirus has infected 181 people and so far killed 31, the Korea Centers for Disease Control and Prevention said Friday. About one in five of the cases will probably be fatal, Benjamin Cowling and colleagues at the University of Hong Kong wrote in a study.
With the outbreak appearing to be ending, public health authorities may start to probe how a deadly disease was allowed to spread so quickly, the authors said. At least three-quarters of the cases can be attributed to clusters in hospitals started by three highly infectious people, or superspreaders. The index patient spread the virus to 27 people in one hospital alone.
“This outbreak demonstrates the potential for clusters of emerging infectious diseases to have very substantial societal and economic impact,” wrote the researchers, who work at the university’s World Health Organization Collaborating Centre for Infectious Disease Epidemiology and Control. The parallels with “the spread of SARS in 2003 in Hong Kong and Singapore emphasize the importance of understanding these events” to prevent their recurrence in future.
South Korea announced a stimulus package Thursday of more than 15 trillion won ($13.5 billion) to cushion the economic impact of the disease, which forced the finance ministry to cut its outlook for economic growth this year to 3.1 percent.
Fatality risk
The virus, first detected in 2012 and thought to originate in camels, has an average incubation period of 6.7 days, according to the authors, who analyzed publicly available data from the Korea CDC, the Korean Ministry of Health and Welfare, the WHO and local Korean news reports. They found infected people aren’t likely to spread the virus to others before they start feeling unwell.
As of June 19, 24 people had died of the disease, 30 had recovered and been discharged and 112 remained in the hospital, 16 of whom were in critical condition, according to the study in Thursday’s Eurosurveillance, a weekly online journal on infectious diseases published by the European Centre for Disease Prevention and Control in Stockholm.
One of the superspreaders who contracted the disease from the index case passed the virus to at least 70 others in the emergency room of one of Seoul’s five largest hospitals. Another patient spread it to 24 others, the researchers at the University of Hong Kong said.
More than 1,300 laboratory-confirmed cases of MERS have been reported worldwide since 2012, including at least 475 deaths, according to the Geneva-based WHO, which said the virus hasn’t developed the ability to spread easily between people. In contrast, influenza kills 250,000 to 500,000 people a year.
“MERS reminds us of the massive amount of fear that emerging infectious diseases can provoke,” said Cowling, an associate professor of infectious disease epidemiology, in an interview. “While the number of people that die from illnesses like influenza or other infections in South Korea is many times greater than those that died from MERS -- you see much greater societal and economic impact from MERS.”

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