Coronavirus: What Is It?

A virus that has killed half the people it's infected causes worldwide concern. Continue reading →

A virus that has killed half of the people it's known to have infected could pose "a threat to the entire world," director-general of the United Nations' World Health Organization Margaret Chan said at the 66th World Assembly in Geneva, Switzerland, on Monday.

What is a novel coronavirus?

The coronavirus family encompasses viruses of varying severity, causing illnesses from the common cold to SARS (severe acute respiratory syndrome).

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This strain, now being called the Middle East respiratory symptom coronavirus, or MERS-CoV, "is different from any other coronavirus previously found in people," according to the Centers for Disease Control and Prevention.

Symptoms include fever, cough and shortness of breath, leading to pneumonia in some cases. Health officials are still trying to pin down how it infects humans. Although the CDC says there is "clear evidence" of human-to-human transmission, it doesn't appear to spread as quickly and easily as SARS did in 2003. Since then, monitoring techniques have improved so that more viruses are being detected - most of which, experts have said, will not pose any grave threats.

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Still, "we understand too little about this virus when viewed against the magnitude of its potential threat," CNN quotes Chan as saying. "We do not know where the virus hides in nature. We do not know how people are getting infected. Until we answer these questions, we are empty-handed when it comes to prevention. These are alarm bells. And we must respond," she said.

The WHO is monitoring infections worldwide: The current tally has 44 reported cases of infection since September 2012 and 22 deaths.

Photo: Celeste Romero Cano/Getty Images