Saudi Arabia announced on Wednesday that 18 more people had contracted the form of coronavirus known as Middle East Respiratory Syndrome, or MERS.
The disease, which causes pneumonia-like symptoms and can be fatal if left untreated, now affects 449 people in Saudi Arabia. According to Reuters, at least 121 people have died of the disease in Saudi Arabia since it was first identified two years ago, which makes for a high mortality rate of about 29%.
Doctors across the world are worried about MERS because it belongs to the same family of infectious diseases as the Severe Acute Respiratory Syndrome (SARS), which killed some 800 people in China in the early 2000s.
Coronaviruses generally originate in another animal species — known as its "reservoir" — before migrating to humans. SARS, for example, is thought to have originated in bats. Scientists are still looking for MERS' reservoir, although camels are suspected.
So far, cases have been reported in Saudi Arabia, Qatar, Kuwait, Jordan, United Arab Emirates, Malaysia, Oman, Tunisia, France, Germany, Spain, Italy, Britain, and the United States.
The virus has spread to the United States, but so far only one patient has been reported — and is doing better.
Nicolás Medina Mora is a reporter for BuzzFeed News and is based in New York.
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