PHOENIX – A third person in Arizona, a health care worker, has been diagnosed with the COVID-19 coronavirus, state health officials said Friday.

The case is being treated as the state’s first spread through the community rather than from contact with a known source.

“We have not been able to link this patient back to one of our current cases or any history of travel,” Dr. Cara Christ, Arizona Department of Health Services director, told KTAR News 92.3 FM.

The patient, a woman in her 40s, is hospitalized in stable condition in Maricopa County, authorities said. She works in Maricopa County and lives in Pinal County.

Officials declined to be more specific about details in order to protect the patient’s identity.

Investigators have been in touch with her close contacts to alert them about the diagnosis and monitor their conditions.

“This individual did not expose very many people at all because she was vigilant about staying home when she was sick,” Dr. Rebecca Sunenshine, Maricopa County Department of Public Health director, said during a press conference.

The woman was diagnosed by a state lab, which makes it a presumptive positive case until confirmed by the Centers for Disease Control.

The state has one other presumptive positive case that was revealed this week, plus a confirmed case from last month.

The first case was a member of the Arizona State University community who has fully recovered.

The second, which was announced Tuesday, was a man in his 20s who is recovering at home in Maricopa County. He recently traveled with a person who later had a presumptive positive test in Florida, officials said.

The state was certified to begin conducting its own testing on Monday. Previously, tests had to be sent to the CDC, resulting in a slower diagnosis process.

As of Friday morning, 51 people in Arizona had been tested for the virus. In addition to the three positives, 33 people had been cleared and 15 results were pending.

The ADHS is providing test result updates online each morning.

COVID-19 has infected more than 100,000 people worldwide, killing more than 3,000, since the outbreak began in Wuhan, China.

The virus has killed more than a dozen people in the U.S. and infected more than 200.

KTAR News 92.3 FM’s Peter Samore and The Associated Press contributed to this report.

KTAR News 92.3 FM will air a two-hour live “20/20” special from ABC at 7-9 p.m. Friday: “Outbreak: What you Need to Know.”

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For all articles, information and updates on the coronavirus from KTAR News, visit ktar.com/coronavirus.