TMC PULSE

t m c » p u l s e | a u g u s t 2 0 1 7 20 'It's a crappy test' Although TB is preventable, treatable and curable, it is one of the top 10 causes of death worldwide. According to the World Health Organization, TB kills close to 1.5 million people annually. Traces of the disease, known for centuries as consumption, have been found in the remains of Egyptian mummies. TB claimed the life of 19th-century English poet John Keats, at a time when the "white plague" was rampant and romanticized. Eleanor Roosevelt died from complications of TB. Perhaps because it has been around for so long, many people assume TB has been eliminated. "When my wife and I got engaged, her father asked what I do and she said, 'Well, he takes care of kids with TB,'" Starke said. "Her father looks at her and goes, 'Well, he doesn't have a future.' And that was 38 years ago. Most people think it is gone, but there are still 10,000 cases per year in the U.S." TB kills more people every year than AIDS, though the American public sees and hears much less about it. It takes high-profile cases—like the high school students in Fort Bend County—to pull the disease out of the shadows and into the news cycle. For White and her partner of 27 years, Patricia Johnston, the diagnosis was shocking. "I call her 'doctor freak' because she just loves getting up and going to the doctor," Johnston said of White. "She's always telling me, 'You gotta take care of yourself.' And that's why I don't understand how she got so sick. She had been going to the doctor for two years to see what was wrong and they told her it was cancer because of the damage on her lungs. But it wasn't." At Ben Taub Hospital, White was treated by Elizabeth Guy, M.D., medical director of pulmonary clinics at the hospital and an assistant professor of medicine at Baylor College of Medicine. Guy was surprised Smith wasn't diagnosed sooner. "She had developed some lung lesions we were investigating and, in fact, we could not prove that she had latent TB at some point in the past," Guy said. "It seems like she must have had it, but our tests are quite imperfect and did not pick up on it." A chest X-ray and a sample of sputum (phlegm) are needed to determine whether a person has active TB. A positive TB skin test or TB blood test only shows that a person has latent TB infection. Misdiagnosis is all too common in the world of TB. Testing is antiquated and unreliable. "The skin test is a bump on the arm," Starke said. "It's a crappy test." The skin test, which dates back to the 19th century, involves injecting TB protein (antigens) under the top layer of skin on a patient's inner forearm. If the patient has been exposed to TB, a firm red bump develops within 48 hours. "We used to do medicine by reading bumps on people's heads—phrenology—and that was in the Dark Ages," Starke said. "It's a horrible test. It's hard to place, hard to read. It takes special expertise and people are bad at it." Even if a skin test is administered and read properly, it can take six to eight weeks after a person is exposed to TB for a positive infection to be identified. Moving toward early detection Jeffrey Cirillo, Ph.D., a professor at the Texas A&M Health Science Center College of Medicine and director of the Center for Airborne Pathogen Research and Imaging, has been working on a rapid diagnosis test to detect active TB in real time. Still in clinical trials, the TB REaD takes a sample of sputum from the regularly administered test and mixes it with a chemical compound that allows Cirillo and his team to spot the bacteria in a matter of minutes. TB REaD delivers a diagnosis of positive or negative in about half an hour. "Worldwide, people don't get diagnosed until they've already transmitted the infection," Cirillo said. "The idea would be to detect them very early on when they first visit a clinic. The process of test- ing has been an issue because no one had a method for sensitively detecting tuberculosis during the early stages of the infection." White in the examining room at the Smith Clinic, part of Harris Health System. White gets a chest X-ray at the clinic.

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