Three people in Saudi Arabia who contracted the Middle East respiratory syndrome coronavirus, or MERS-CoV, have died, bringing the death toll from the illness to 27 and the total number of reported cases to 49, according to the Centers For Disease Control and Prevention. A patient infected with the same virus died in France on Tuesday.

With those recent deaths, more than half the people who have contracted the virus, which was first identified in humans last September, have died. Speaking at the annual World Health Organization meeting in Geneva on Monday, WHO head Dr. Margaret Chan said that the SARS-like virus could potentially be a huge threat.

"We understand too little about this virus when viewed against the magnitude of its potential threat," said Chan. "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."

MERS-CoV is in the same family of viruses as Severe Acute Respiratory Syndrome (SARS), which killed around 800 people in an epidemic in 2003.

The WHO suspects that the MERS-CoV may be transmitted from person to person, but it isn’t quite sure exactly how it is spreading.

“There are many other things that we don’t understand,” said a recent WHO press release on the virus. “For example, how are people getting infected? Is it from animals? Is it from contaminated surfaces? Is it from other people? Finally, we don’t know how widespread is this virus, both in this region [France] and in other countries.”

That’s why the WHO is encouraging countries to step up monitoring for the virus in order to quickly identify clusters and better understand how the virus is spreading. Check out this map of all reported cases of the novel coronavirus since 2012. Click on any bubble to see how many cases of the infection were reported in that region and how many of those afflicted died. A larger bubble indicates a higher number of reported cases in that country.