A health worker at an El Paso, Texas, hospital may have exposed more than 700 infants to tuberculosis.

Parents of children born at Providence Memorial Hospital between September 2013 and August 2014 received a letter from the El Paso Department of Health stating that an unnamed female employee had the illness during this time.

According to ABC News, the employee was originally said to be a nurse working in the hospital, but was later revealed that she was a patient care tech. The letter told parents that they could receive free TB screenings and treatment at the El Paso Department of Health.

"Your child should receive [a] TB skin test as soon as possible in order to determine if he or she has the TB germ," the letter read. "A nurse will look at the arm in 2-3 days to read the test. Your child will also need a chest X-ray so that a doctor can check to see if your children's lungs are clear. A doctor will examine your children and answer any questions you may have. If it is needed, medication will be provided to further protect your child."

A hospital spokesman said in a statement that the employee had been on leave since Aug. 16. The El Paso Department of Health posted an exposure schedule, which showed when it was more like patients in the nursery of the hospital could have been infected. Dozens of the employee's co-workers might also have been exposed to TB.

City health department spokesman Armando Salivdar said officials used the Centers for Disease Control and Prevention's guidelines to determine how long of a testing range to alert.

"We took the date of first signs and symptoms [of the health-care worker] and went back three months to determine who is considered 'exposed,'" Salivdar said to the AP.