The state health department said there is a second confirmed case of tuberculosis in Ellis County, while the Denton school district said it would test hundreds of students for exposure to the infection.
Health officials did not release any information about the case.
The Texas Department of State Health Services said 221 people in Ellis County have tested positive for exposure to tuberculosis after a high school teacher was diagnosed with the disease. Health officials have analyzed 1,577 skin tests in Ellis County, the department said.
The mother of 16-month-old Jazel Henderson said her child was exposed to relatives who attend Ennis High School. Jazel is now home after weeks of tuberculosis treatment.
"This is very frightening," Markeish Goss, the baby's mother, said. "I've never been through anything like this in my whole life ever."
A Denton High School student who attended Ennis High School last year was hospitalized Tuesday with a suspected case of tuberculosis.
The Denton Independent School District said it would carry out an emergency plan to test hundreds of students for exposure to the disease.
"This is all a precautionary measure," district spokeswoman Sharon Cox said. "We want our students to be healthy and safe throughout the district. We don't want parents to panic."
The district, which is working with the Denton County Health Department, will conduct skin tests on about 200 students Tuesday.
"We looked at the rosters, and we contacted any student that was involved in his activities or classes, and we also contacted students that were on the bus with him," Cox said.
Anyone who was in close contact with the student who has the suspected case of tuberculosis is asked to get tested.
Doctors say people are only at risk for contracting the airborne bacterial infection if they are in close proximity to a person with an active case for a prolonged period of time. Casual contact should not lead to an infection.
Dr. Bing Burton, the director of the Denton County Health Department, said the skin tests will give health officials a sense of how active the disease is.
"Have there been multiple exposures, or did we catch this thing really soon and maybe there haven't been exposures?" Burton said.
Those who test positive for exposure to tuberculosis will get a chest X-ray.
All of the people tested will also get a second skin test in 10 weeks. Health officials said two tests are necessary in case new cases develop.
"It is possible that at some point, there might be an expansion to do a skin testing of the entire school," Burton said.
Denton High School parent Heidi Klein said she agreed with the district's strategy.
"I think it is better to be overly cautious with those kids but not create a widespread panic with the entire student population. ... If in two weeks, eight, nine, 10 kids are home sick with an active form, you know, yeah, maybe we will be a little more worried then," she said.
NBC 5's Ken Kalthoff contributed to this report.