Colorado’s San Juan County has reported its first confirmed case of COVID-19.

San Juan County Public Health Director Becky Joyce said a resident was tested late last week for IgM antibodies. Results that came back Monday showed the person tested positive, she said.

There are two kinds of antibody tests: the IgM, which tests for antibodies that may indicate whether a person is actively infected, and the IgG that tests for antibodies that remain in the bloodstream after the infection has passed.

On top of the positive IgM test, Joyce said other factors contributed to determining the confirmed case.

Joyce didn’t get into specifics, citing patient privacy, but said factors such as whether the person was showing symptoms of the virus or if the person had recently been in contact with an infected person were taken into consideration.

Ultimately, the Colorado Department of Public Health and Environment determined there was enough evidence to deem the case probable and count it on the state’s positive case list, Joyce said.

Ian Dickson, a spokesman for CDPHE, said the state’s case counts have always included probable cases.

Cases are considered confirmed, he said, when a person meets a combination of criteria, such as exhibiting symptoms, coming in close contact with an infected person or testing positive in an IgM test.

San Juan County was one of a handful of Colorado counties that had not reported a confirmed coronavirus case. Counties still without a positive confirmed case include Bent, Cheyenne, Conejos, Dolores, Jackson, Kiowa and Sedgwick.

During the outbreak, San Juan County has taken strict measures to reduce the virus’ spread, including closing off the town of Silverton to outsiders and prohibiting unnecessary travel into the county, effectively closing public lands.

But the absence of confirmed cases was also attributed to the lack of testing. Only recently has the community been able to offer testing. Previously, Silverton residents had to travel to Durango or Montrose for tests.

Despite all those factors, Joyce has maintained the coronavirus was likely in Silverton, but to what degree has been unknown.

“We’re really not surprised,” Joyce said of the positive test result.

After receiving the positive result around 10 a.m. Monday, the person was notified about an hour later. Health officials then began contact tracing – identifying people who may have come into contact with an infected person.

“There were one or two people we followed up with,” Joyce said. “Essentially, we were very lucky because we have had strict guidelines in place for Silverton ... so this person didn’t have a lot of contact with other people.”

On March 24 – two days before Gov. Jared Polis’ stay-at-home order – Joyce enacted a public health order that prohibited outside visitors and unnecessary travel into the small mountain town north of Durango. It was one of the strictest in the state.

San Juan County is now under Polis’ “safer-at-home” order, which allows some businesses to reopen. Surrounding public lands, however, still remain largely off limits as a result of a clause in the state order that prohibits travel of more than 10 miles for recreational purposes. San Juan County is so remote that even surrounding communities must travel farther than 10 miles to access it.

“We won’t know for sure, but we can hope that helped the situation,” Joyce said.

As restrictions are eased, and more of Silverton’s summer residents return, the community now has the ability to test.

San Juan County Public Health opened a free testing site Monday for the PCR test, a nasal swab that determines whether a person is actively infected. The site does not offer antibody tests.

As of Thursday, Joyce said only one person had come in for a test. The health department had not yet received those results.

“I’m just very relieved we have a test site,” she said.

Silverton Clinic, a nonprofit primary care facility staffed by a Mercy Regional Medical Center nurse practitioner, is offering the IgM antibody test.

Joyce said a grant from the Help Colorado Relief Fund helped fund the health department’s test site and hire a former public health director to assist with contact tracing.

jromeo@durangoherald.com