Disease trackers are accustomed to hunting deadly new pathogens in Africa’s jungles and Asia’s megacities. The sand dunes of the Middle East? Not so much. But that’s the birthplace of the latest previously unknown virus to spread globally: Middle East Respiratory Syndrome coronavirus, or MERS-CoV. Exactly where the virus comes from remains a mystery, but camels are thought to be the source of many human infections. It’s most dangerous for people with underlying health conditions and is often lethal.
Three years after MERS emerged in Saudi Arabia, the first major outbreak of the disease occurred outside the kingdom, in South Korea in May 2015. That reignited concerns of a global health emergency akin to the Severe Acute Respiratory Syndrome (SARS) epidemic of 2003. Also for the first time, the disease was exported to a third country when an infected South Korean man went to China after ignoring instructions not to travel. Globally, the virus has sickened more than 1,300 people and killed more than 460, the vast majority in Saudi Arabia. MERS was first identified in the desert kingdom in 2012, when a 60-year-old Saudi man died with severe pneumonia and kidney failure, though a subsequent analysis found two earlier cases in Jordan. The virus appeared to be on the wane until April 2014, when the case count exploded. Contact with camels during the spring, when females wean their young, may have contributed to the surge in new cases, which was amplified by poor infection control in hospitals. Despite concerns that the annual pilgrimage of Muslims to Mecca and Medina in mid-October would spread MERS, not a single case was attributable to the pilgrimage, according to the World Health Organization. The virus does not appear to pass easily from person to person. While cases have been reported in the U.S., Europe, Asia and Africa, all have been in people who live in or traveled to the Middle East, or who were exposed to someone who did.
MERS-CoV belongs to the same family of pathogens as the SARS virus, which killed about 800 people worldwide after first appearing in China in 2003. MERS-CoV turned up in three-quarters of samples taken from camels across Saudi Arabia, according to a study published in early 2014. Camel herders and people who visited a camel farm or consumed unpasteurized camel milk have been among those infected. The virus has also been found in bats, suggesting that they may be a natural reservoir. MERS causes fever, cough and shortness of breath, leading in severe cases to respiratory failure, organ failure and death. People with weakened immune systems are more at risk. There’s no vaccine and no specific treatment. Despite the spread of the virus to South Korea and China, there’s no evidence that it has mutated into a more transmissible form, according to the WHO. Most of the cases in which people passed along the disease involve family members or health-care workers who were exposed.
The World Health Organization has declared global public health emergencies only three times. In 2009 for the H1N1 influenza (swine flu) pandemic, in May 2014 when it announced that polio had rebounded after almost being eradicated, and in August 2014 when Ebola ravaged west Africa. The WHO’s emergency committee has met to discuss MERS nine times since July 2013 and each time decided against labeling it an emergency, in large part because of its limited transmission between humans. Rather than suggest travel bans or other global measures that could raise anxieties, the agency said health-care workers should take standard infection-control measures, such as washing their hands between patients, and wear protective equipment when treating those with symptoms of acute respiratory infection. Amid criticism that South Korea missed opportunities to contain MERS early, WHO convened a team of specialists to study the country’s response and recommend measures for ending the epidemic.
The Reference Shelf
- Read the World Health Organization’s answers to frequently asked questions on MERS-CoV.
- The U.S. Centers for Disease Control and Prevention has MERS pages for health-care providers and for consumers.
- German virologist Christian Drosten talks about his observations from a trip to Saudi Arabia and his analysis of the virus.
- Stay up to date with infections in Saudi Arabia on the Saudi Health Ministry’s MERS website.
- Read Thomas Abraham’s book, “Twenty-First Century Plague: The Story of SARS.”
First published May 19, 2014
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