Tuberculosis: Crack the code

EDINBURG — Scientists in a sealed-off laboratory are working to understand an ancient disease that still flourishes along the border.

Researcher Dr. Subramanian Dhandayuthapani, called “Dr. Pani” by his colleagues, is committed to learning more about tuberculosis, including its genetic composition, behavior and ability to remain dormant in the body for decades.

He’s also trying to improve an imperfect vaccine for the disease, making it more effective and predictable.

Scientists across the country are investigating these topics, but Dhandayuthapani said he wanted to work from a place particularly affected by the virulent disease.

“Here, there are more tuberculosis patients to work with,” said Dhandayuthapani, who previously conducted his research from the University of Texas Health Science Center at San Antonio, of which the Regional Academic Health Center in Edinburg is part.

“Eventually, I might start some population studies here to understand why people here are susceptible to TB.”

Tuberculosis is an airborne disease that often affects the lungs, but also can infect the brain, spine or kidneys, according to the U.S. Centers for Disease Control and Prevention.

Many people who are exposed develop a latent form of the disease, which has no symptoms. Symptoms of active disease could include weight loss, fever, chills, and in TB of the lungs, coughing up blood and chest pain. The disease can be deadly if it isn’t treated.

Shrouded in mystery

According to statistics from the Texas Department of State Health Services, TB continues to be a significant presence in the Valley.

In 2006, the latest state data available, Cameron County recorded 64 confirmed cases of tuberculosis and Hidalgo County 68.

With some minor fluctuations, the number of cases has stayed fairly consistent in the last five years, according to state data. But the incidence along the border is much higher than in the rest of the state. Most Texas counties only recorded a handful of cases in 2006.

That’s why it makes sense to conduct research on tuberculosis here, said Dr. Leonel Vela, regional dean for the RAHC.

“It’s very important research, because it focuses on a disease that disproportionately affects our population here, in the border area,” Vela said. “Tuberculosis is a disease in which we have observed ebbs and flows, but it’s one we haven’t been able to fully tame.”

Dhandayuthapani and his colleagues are trying to crack a few of tuberculosis’ mysteries.

The first is the bacteria’s skill at outsmarting the human immune system and remaining dormant in the body for many years, Dhandayuthapani said.

Many adults who develop active TB disease have a “reactivated” form, meaning they already had the bacteria in their bloodstream but it suddenly became active.

“When a person is infected, they often don’t develop the disease immediately,” Dhandayuthapani said. “(The bacterium) has the ability to stay dormant indefinitely, and in that period it won’t multiply. But when the immunity is compromised, all of a sudden it gets activated and produces the disease.”

The researchers are trying to identify the mechanism the bacteria use to hide from the body’s natural defenses during dormancy, he said. When the bacteria are latent, antibiotics

can’t fully kill them, he said.

Many people with latent TB never develop active disease, but for some, especially people with weakened immunity, it suddenly kicks in, according to the CDC. The disease isn’t contagious when dormant.

A vaccine

People with HIV or AIDS, leukemia or kidney disease are particularly susceptible to developing active TB, the CDC says.

In his research, Dhandayuthapani also is looking into why diabetics are vulnerable to tuberculosis, as well.

“We’ll be looking at the molecules produced by the immune system, and comparing healthy patients with diabetes patients,” he said.

Finally, the researchers are studying the only vaccine available for tuberculosis. The vaccine, known as BCG, is rarely used in the United States because it’s unpredictable and skews skin tests for the disease, according to the CDC.

The agency only recommends the vaccine for children who are constantly exposed to active disease or for healthcare workers who are frequently exposed to people with drug-resistant TB.

The vaccine still has the potential to make people sick, and Dhandayuthapani is looking at ways to shut off certain genes to make it less virulent.

“By knocking out one of the genes, it becomes effective in producing immunity … but then it can’t cause the disease,” he said.

Many other researchers are racing to develop an effective TB vaccine, he said.

The RAHC has a special lab for the purpose of studying lethal diseases like TB. The lab, classified as “biosafety level 3” by the CDC, is carefully sealed and closed to visitors. Lab technicians must wear full protective gear to enter.

Researchers do much of their preliminary work with less lethal bacteria, like e. coli, before moving on to tuberculosis, he said.

Dhandayuthapani’s ultimate goal is to prevent and better treat TB, he said.

“This disease kills so many people … I want to eradicate it through this research,” he said.

His research is likely to have a big impact, Vela said.

“These are important questions for us here, and worldwide,” Vela said.

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Melissa McEver covers health and environment issues for Valley Freedom Newspapers. She is based in Harlingen and you can reach her at (956) 430-6252.