Students and staff members who tested negative for TB during the first round of tests in September are being re-tested.
A second round of tuberculosis tests were conducted at Ennis High School Monday to determine the level of exposure students were subjected to following a teacher's diagnosis with the contagious bacteria earlier this year.
The tests are being conducted by the Texas Department of State Health Services (TDSHS).
Students and staff members who tested negative for TB during the first round of tests in September are being re-tested, because incubation can take 8 to 10 weeks, according to TDSHS.
That means someone who tested negative for TB before could test positive now.
During the initial round of testing, TDSHS identified 224 (out of 1,732) people who tested positive on the skin tests. A positive test means the person has been exposed to TB, not necessarily that they have TB, according to TDSHS.
Jazel Henderson was infected with tuberculosis after her two cousins, whom she lives with and who attend Ennis HS, both tested positive.
"This is the worst thing I've ever experienced in my whole entire life, like the worst thing, " said Henderson. "[I've] never been through something so traumatic and never want to ever again."
Someone who tests positive will then undergo chest x-rays to determine if they have active TB. Those with clear x-rays were diagnosed as having latent TB, which is not contagious and can be treated with a regimen of antibiotics.
This started before the school year began, when a high school teacher was diagnosed with active TB. That teacher has been cleared to return to the classroom, but is not a presence at the high school or any other Ennis Independent School District campus, district officials said.
NBC 5's Ray Villeda contributed to this report.