A worker at BP Plc's operation in Alaska's North Slope has tested positive for the novel coronavirus that has killed more than 42,000 people worldwide, the company confirmed Tuesday.

It is the first case at an Alaskan oil installment in the North Slope, where the vast majority of the state's oil is produced. The worker at BP Prudhoe Bay has been isolated, the state's chief medical officer said.

"BP is following procedures and protocols to minimize the risk of COVID19 and ensure the safety of our people. We are eliminating all non-essential activity on the slope," said Megan Baldino, spokeswoman for BP Alaska.

More than 850,000 people have been sickened worldwide by the coronavirus pandemic, and governments have imposed quarantines or other restrictions to try to stop its spread. Fuel demand has dropped precipitously as motorists stay out of cars and commercial aviation has largely stopped.

The worker was an Alaska resident who had recently traveled out of state, its department of health and social services said in a statement, clarifying earlier remarks by the chief medical officer, Dr. Anne Zink.

The patient returned to Alaska before travel curbs imposed on March 23, going to the North Slope on March 25.

Oil companies in the isolated North Slope had already put safety measures in place to try to avoid infection, including paring workforces, lengthening shift rotations so there are fewer flights in and out, and conducting health screenings before workers fly in.

BP had also imposed a mandatory 14-day self-quarantine for all workers and contractors before they board planes bound for the North Slope.

As of Tuesday afternoon, Alaska had a total of 133 positive cases, Zink said.