Every Ennis High School student will be tested for exposure to tuberculosis after more than 100 people have tested positive.
More than 800 students, staff members and anyone who has been in close contact with them have been tested after a teacher was diagnosed with the bacterial infection before the start of school.
The school district announced late Thursday that the students and faculty who have not been tested will get free tuberculosis screenings beginning Monday.
Frustrated parents told state health officials at a public meeting Wednesday night that every student needs to be tested.
The Texas Department of Health and Human Services reached out to Dallas County Health and Human Services for help.
Dallas County is one of few that has a dedicated Tuberculosis Elimination Division.
The county also wanted to get involved because it has received dozens of phone calls from parents and school districts concerned that the infection might spread between players at athletic events.
Concerned callers said they were worried that the infection could spread if one player's sweat is wiped on another. But Susan Kent, the nurse supervisor for the Tuberculosis Elimination Division said there is "no chance" of that happening.
"It is an airborne infection," she said. "It is not spread by body fluids. You have got to spend prolonged periods of time in a closed environment with someone who is coughing and spewing out those germs."
Kent also said people who have tested positive on a skin test but do not have an active case of tuberculosis are not contagious.
"Let's say if you do have someone on the football team with a positive skin test, he cannot give anything to anyone. He would have to have an active case," she said.
Positive skin tests indicate the person has been exposed to tuberculosis but do not mean that the person has the infection.
People with positive skin tests receive a chest X-ray. If the chest X-ray shows abnormalities on the lungs, it's possible the person has an active case of tuberculosis, and further testing is needed.
Dr. Garry Woo, medical director for the Tuberculosis Elimination Division, said the precautions some districts have told their students to abide by are unnecessary.
"Measures such as wearing masks, avoiding the athletic event, bringing your own water -- these are unnecessary," he said.