MURRIETA ( — Families in Murrieta are on edge after a high school student tested positive for tuberculosis.

The student at Vista Murrieta High School tested positive for an active case of the lung and throat disease, known to spread through the air.

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Murrieta Valley Unified School District found out about the infected student Wednesday, and by Thursday morning Vista Murrieta parents were notified. The school is expected to be closed on Friday.

“I just got a call and e-mail and I thought, great,” concerned mother Deanne Hazel said.

Part of the letter sent to parents says the student is not in school and will not return until it’s safe to do so.

The district is not identifying the student, but spokeswoman Karen Parris confirmed the teenager is being treated and is expected to make a full recovery.

“The health department has assured us that the potential for transmission is very low, and we’re hoping that will be the case,” Parris said.  She acknowledged, though, that several hundred students could have been exposed to the infected child.

District officials have posted a TB fact sheet on their website.

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The  Riverside County Department of Public Health is working with school officials to contact those who might have been exposed to the illness.

Officials say parents whose children were exposed will get another notice and a phone call.

Anyone who receives the notice and is at risk of being exposed to the illness is advised to get a TB skin test at a clinic being planned at the school.

The incubation period following exposure is two to 10 weeks, so waiting at least two weeks before testing is recommended.

More information is available on the Riverside County Department of Public Health’s website and on the website for the Center for Disease Control.

Parents may also contact their health care provider or the Public Health Department Disease Control at (951) 358-5107.

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Anyone with questions may also call the district’s health services coordinator, Cathy Owens, at (951) 696-1600, ext. 1027.