A handful of students at a high school in Irving have tested positive for exposure to tuberculosis.
The Irving school district said five people out of 137 at Nimitz High School tested positive for exposure to TB in preliminary skin tests. Students and teachers who had might have had contact with a student diagnosed with the bacterial infection between March and May had skin tests.
Positive skin tests indicate the person has been exposed to tuberculosis but do not mean that he or she has the infection or will contract it.
The student was diagnosed with tuberculosis at the end of the summer and is getting treatment. The student is not currently attending Nimitz.
Tuberculosis is an airborne bacterial infection. It typically attacks the lungs but can also affect other organs, such as the brain, kidneys or spine. It can be fatal if not treated. Symptoms include flu-like conditions including coughing, fever and weight loss.
People are only at risk for contracting the infection if they are in close proximity to a person with an active case for a prolonged period of time -- 40 to 80 hours over the course of several weeks. Casual contact such as a conversation, sports or a car ride should not lead to 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.
NBC 5's Omar Villafranca and Christine Lee contributed to this report, which also includes background information from previous stories.