Nearly 150 vendor employees at a Microsoft facility in Redmond are being tested for tuberculosis after contact with an individual who was recently diagnosed with an active form of the disease, Public Health — Seattle & King County reported Thursday.

“The risk of infection to the close contacts is low, and we’re doing testing as a precaution,” said James Apa, Public Health spokesperson, in an email Friday.

Microsoft declined to comment about the reported exposure, and as of Friday afternoon which Microsoft facility was involved or what steps the company was taking to help exposed vendor employees.

Apa, who initially reported the incident on the agency’s website, said during an interview Friday he could not provide additional information about how or when the exposure occurred in order to “protect the patient’s medical privacy.”

He did say Public Health has been at the Redmond facility this week to evaluate and test people who were exposed. He also said the person who was diagnosed with active TB is receiving treatment and that vendor companies have notified their affected employees.

TB is an infectious disease caused by bacteria that are passed from person to person through the air, according to Public Health. TB is much harder to spread than a cold or flu, and it typically takes repeated and prolonged exposure in a confined indoor space to become infected. Even in households where a resident is infected with contagious TB, only about one in three close household contacts become infected, according to Public Health.

In King County, 134 new cases of TB were reported in 2019, Public Health reported.

According to the U.S. Centers for Disease Control and Prevention, there were 9,025 reported cases of TB in the United States in 2018, the most recent year listed on the agency’s TB website. In Washington state, the rate of infection was 2.8 per 1,000, which is the same as the national average, in 2017, the most recent year listed on the CDC website.