The US just issued a travel warning on China because of the mysterious coronavirus outbreak

• The US State Department issued an upgraded travel warning on China, citing the coronavirus outbreak.
• The warning was raised from level two, or "exercise increased caution," to level three, "reconsider travel."
• More than 4,600 have been infected by the virus, with at least 107 fatalities.
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The US State Department issued an upgraded travel warning on China, as concerns over a mysterious viral outbreak continue to grow.

The warning level was raised from level two, or "exercise increased caution," to level three, "reconsider travel," on Tuesday.

More than 4,600 people have been sickened by the virus, and at least 107 have died.

The coronavirus, which causes pneumonia-like symptoms was first observed in the city of Wuhan, China, a city of 11 million in the Hubei province.

The entire city of Wuhan has been quarantined by Chinese officials, with transportation links to the city suspended. At least 15 other cities in China have been quarantined or had transit links suspended.

The virus has spread to at least 16 other countries, including the US.

It is believed that the virus, which is known officially as 2019-nCoV, originated in animals - possibly snakes - before jumping the species barrier to humans. The outbreak was traced to a seafood market in Wuhan that sold live animals. The disease can also be passed person-to-person.

US health officials began screening incoming passengers from China at airports earlier this month. The federal government said on Tuesday that it would expand those screenings to more airports around the country.