DENVER -- A prisoner at the Sterling Correctional Facility who was diagnosed with tuberculosis is now being treated at a Denver hospital while prison staff and other inmates are being tested for the disease.

The prisoner first tested positive for the disease two years ago but his TB wasn't active, and therefore, not contagious.

Health officials with the Department of Corrections and the Northeast Colorado Health Department are identifying staff members and other offenders who had contact with the infected inmate to determine who might be at risk. DOC spokeswoman Katherine Sanguinetti said the case is highly suspicious and that is why all the staff and offenders are being tested.

Prison officials in Sterling have barred visitors to the facility as inmates and guards are being tested.

The inmate, who has not been identified, has been serving time for menacing and drug-related charges since 2001.

Sanguinetti said inmates are tested annually for TB, but this inmate was tested after showing symptoms. TB is caused by a bacteria and spreads from person to person through the air.

The DOC said it has an ongoing process for monitoring communicable diseases including TB. All offenders are screened at the Denver Reception and Diagnostic Center when they are received and annually thereafter. TB treatment protocols are in place for offenders including chest x-rays and medications.

This process is expected to extend through next week when all tests are administered and results are completed.