The new coronavirus disease sweeping the globe has reached Colorado, state officials announced Thursday, warning that even more cases are now likely to be confirmed as they ramp up testing for COVID-19.

Two individuals tested positive for the novel coronavirus disease and at least another three people are in quarantine, state officials said.

Older people and those with pre-existing health conditions are most at risk from the deadly disease, which originated in China.

“It’s a virus that seems to be spreading slowly, but what we’ve seen from other countries and from other states is that the more we test, probably the more we’ll find,” said Jill Hunsaker Ryan, executive director of the state Department of Public Health and Environment.

“The fact that 80% of cases are mild means that up to this point they probably won’t be hospitalized, haven’t sought medical treatment,” she said. “So there really hasn’t been a reason to do wider testing until we realized that people were presenting with this illness.”

Gov. Jared Polis announced the second case at a Thursday afternoon news conference that had been called to discuss the first case.

The state said Thursday evening that the second patient is an older woman from Douglas County who had returned to Colorado from an international cruise. She is “isolated at her home per CDC guidelines,” the state health department said.

“She is currently isolated at home and has had limited public contact, including with her family members and healthcare providers. Tri-County Health Department staff is monitoring people who may have been exposed,” said Dr. John M. Douglas Jr., executive director of the Tri-County Health Department, in a news release. “We are hoping that she recovers quickly.”

The two tests conducted in Colorado are considered “presumptive positive.” State officials now will send them to the U.S. Centers for Disease Control and Prevention for official confirmation.

“Coloradans get sick every day,” Polis said. “And I don’t want anybody to panic because of this.”

The Colorado Department of Public Health and Environment’s state lab can test about 160 samples per day, with results in 24 hours. With two cases now reported in Colorado, Polis said the state plans to expand its testing. So far, the state lab has run 93 negative tests for the disease, and another 38 are pending, he said.

“At the end of the day we have a very robust health care system in this state,” Polis said. “We’ve been preparing for this moment, we are now in execution mode of this plan.”

The first patient to test positive is from out of state. He arrived at Denver International Airport on Feb. 29 and traveled to Summit County. The man, who is in his 30s, was in Italy in mid-February and a person with him on that trip has since tested positive for COVID-19.

On Tuesday, the man went to St. Anthony Summit Medical Center in Frisco after developing symptoms. He is now in isolation in Jefferson County. His wife and two friends, who are Coloradans, are in quarantine, Polis said.

The Denver Department of Public Health and Environment confirmed that the patient’s two friends live in Denver and “have agreed to proactively quarantine themselves” in their home until the full 14-day incubation period has passed. They so far have not shown any symptoms that would call for them to be tested for COVID-19, officials said.

State and local public health officials are working to identify anyone who may have been exposed through that patient, according to a news release.

No specific treatment is available for the new coronavirus, so care for people with mild cases mostly involves medication to reduce fevers, rest and plenty of fluids. People who develop pneumonia, one of the most common complications, may need oxygen or to be placed on a ventilator.

It’s not clear how long the virus could have circulated in Colorado and other states without being detected, because a study estimated it spread undetected in the Seattle area for as long as six weeks. There is no known link between the first patient in Washington, who traveled to China, and other people who became seriously ill, suggesting that people with mild or no symptoms unknowingly spread the virus as they went about their daily lives.

As of Thursday, about 200 cases and 12 deaths from the new virus had have been confirmed in the United States, according to the Associated Press. The virus got a slow start in the United States, with just a few people who were infected when they traveled to China, but has begun to spread in California, Florida and Washington state.

All but one of the deaths so far have been in Washington state, where an outbreak at a nursing home put medically vulnerable people at risk. A patient also has died in California.

Worldwide, the virus infected about 97,700 people as of Thursday, according to The New York Times. About 3,300 have died. The CDC has advised people to avoid nonessential travel to China, South Korea, Iran and Italy because the virus is circulating widely in those countries. People who are at a higher risk of complications also should avoid travel to Japan.

Much is still unknown about COVID-19, but so far it appears to be somewhat less contagious than the seasonal flu. Preliminary data in China suggests about 80% of cases are mild, but that can make managing an outbreak more challenging, because sick people won’t necessarily know they need to isolate themselves. Initial data shows a death rate of about 3% – far higher than the seasonal flu – but it could be that authorities are missing mild cases because people don’t seek medical care.

Most people who have died worldwide were older adults with pre-existing health conditions. Children who are infected have tended to have mild symptoms or none at all, for reasons that aren’t entirely clear.

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