Health officials in United States on Friday confirmed that a resident of Oregon has tested positive for coronavirus with no known history of travel to countries severely affected by the outbreak and no known contact with infected individuals.
The Oregon coronavirus case marks the third case of unknown origin in the United States, indicating that the deadly virus has been spreading fast with no sign of abating, The Washington Post reported.
The patient, meanwhile, is quarantined at Kaiser Permanente Westside Medical Center in Hillsboro.
On Friday, health officials in Santa Clara County, California, said that a 65-year-old resident also had a case of coronavirus with unknown origin, becoming the second US case of community transmission.
The United States' first community-transmission patient was a woman in Solano County.
The World Health Organisation, on the same day, raised its risk assessment of the coronavirus to "very high", citing risk of spread and impact.
WHO officials said their assessment -- the highest level short of declaring a global pandemic -- does not change the approach countries should take to combat the virus but should serve as a "wake up" and "reality check" for countries to hurry their preparations.
The US stock market fell for the seventh straight day amid fears of global economic damage from the escalating outbreak, and the Federal Reserve took the unusual step of issuing a statement to reassure the Americans.
In China -- the epicentre of the deadly disease -- the National Health Commission reported on Saturday at least 47 new coronavirus deaths, raising the death toll to 2,835 nationwide.