Tuberculosis investigation underway at North Texas high school

Dallas County Health and Human Services has launched an investigation into a possible tuberculosis (TB) exposure at MacArthur High School in Irving, saying it may have happened during the previous school year.

DCHHS said it is recommending tuberculosis testing, out of an abundance of caution, for all students who attended the school during the 2025-26 school year and are returning as 10th-, 11th-, or 12th-grade students. The department said the testing advice does not apply to incoming ninth-grade students, new students, or students who were already tested in the 2025-26 school year.

The department notes that the risk to the public remains low and that the testing recommendation does not mean students were exposed to or have tuberculosis. Rather, the department says testing is recommended because inactive, or latent, TB often causes no symptoms.

Irving ISD said it was communicating directly with families, providing them with a letter outlining the testing process and a consent form.

What is tuberculosis?

The Mayo Clinic says tuberculosis is a serious bacterial infection that affects the lungs and can spread when someone with it coughs, sneezes, or even sings. It spreads easily where people gather in crowds or where people live in crowded conditions.

Who is most at risk?

Anyone who lives with a weakened immune system, including someone living with HIV/AIDS, has a higher risk of catching it. People living with diabetes or severe kidney disease are also at increased risk.

Other factors that increase risk include:

• Cancers of the head, neck, and blood
• Malnutrition or low body weight
• Taking cancer treatment, such as chemotherapy
• Taking medicine to prevent rejection of transplanted organs
• Long-term use of prescription steroids
• Use of unlawful, injected drugs
• Misuse of alcohol
• Smoking and using other tobacco products

Additionally, living with someone with an active TB infection can make it easier for the disease to be spread. TB can also easily spread in prisons, nursing homes, and homeless shelters. Living or traveling to countries where TB is common also presents a risk, as does working in healthcare and treating people with a risk for the disease, and living in a community identified as being at high risk for it.

What are the common symptoms?

The most common symptoms of a primary TB infection, according to the Mayo Clinic, include flu-like symptoms such as low fever, tiredness, or a cough.

However, when someone is facing active TB disease, the list expands to include:

• Coughing up blood or mucus
• Chest pain
• Pain with breathing or coughing
• Fever
• Chills
• Night sweats
• Weight loss
• Not wanting to eat
• Not feeling well in general

The Mayo Clinic notes that symptoms of active TB disease outside of the lungs may also include pain near the site of infection, in addition to the symptoms listed above. Common sites include:

• Kidneys
• Liver
• The fluid surrounding the brain and spinal cord
• Heart muscles
• Genitals
• Lymph nodes
• Bones and joints
• Skin
• Walls of blood vessels
• Larynx, also known as the voice box

While teenagers will present symptoms similar to adults, children aged from one to 12 years old may have a persistent fever and weight loss. Infants may act sluggish or not active, vomit, be unusually fussy, face poor feeding, show a bulging soft spot on the head, or show poor reflexes.

To note, the Mayo Clinic says a period of latent TB infection usually follows primary infection once immune system cells build a wall around lung tissue with the TB germs. While the germs can't do any more harm if kept under control, they do survive. There are no symptoms during this stage.

Active TB disease, the Mayo Clinic says, happens when the body can't control an infection. It can unfold right after a primary infection, but it usually happens after months or years of latent TB infection. An active TB disease can spread through the lungs or other parts of the body

When should you see a doctor?

The Mayo Clinic says families should see a healthcare professional if someone has symptoms that don't improve within a few days of rest. Emergency care should be sought if you or a loved one experiences the following symptoms:

• Chest pain
• A sudden, severe headache
• Confusion
• Seizures
• Difficulty breathing

Urgent care should be sought if you cough up blood or have blood in your urine or stool.

How is tuberculosis treated?

People with a latent TB infection may start treatment under the guidance of a healthcare professional. The Mayo Clinic says active TB disease may be treated for 4, 6, or 9 months with medication and regular appointments.

Patients are urged to take every dose as instructed and to complete the full treatment course to kill the bacteria and prevent the emergence of new, drug-resistant bacteria. A public health department may directly observe treatment by having healthcare workers visit to watch someone take treatments.

The Mayo Clinic notes there are a handful of drugs commonly prescribed. While most people can take the medication without serious side effects, a healthcare professional may adjust treatment if serious side effects pop up.

What about drug-resistant tuberculosis?

The Mayo Clinic notes that some forms of TB bacteria have become drug-resistant, meaning medicines that once cured it no longer work. This is because, in part, of naturally occurring genetic changes in the bacteria. These changes might help it survive antibiotic treatment and multiply.

If the medicines fail to clear out the bacteria, or if they aren't used correctly, the Mayo Clinic says conditions are ideal for the bacteria to take hold and multiply, becoming more resistant. If those bacteria are spread, that can lead to a drug-resistant strain growing over time.