The Centers for Disease Control and Prevention recognizes March 24 as World TB Day, bringing awareness to the impact of tuberculosis (TB), prevention efforts, and challenges that prevent the eradication of this disease.
While many Americans think of TB as a problem of the past, or one that exists today only in other countries, the case remains that TB can pose a serious health threat for certain populations. Globally, tuberculosis is still the leading cause of death due to an infectious disease.
“The vast majority of the 3 billion or so people infected with TB bacterium don’t have disease, they just have infection,” says Peter Melby, MD, Professor and Director of the Division of Infectious Diseases, Department of Internal Medicine. “But they can develop disease later in life, so the primary issue of treatment for someone who has just TB infection is trying to prevent the reactivation to disease at a later time.”
TB bacteria is spread through the air from one person to another, and a person’s likelihood of becoming infected depends largely on their proximity to the infected person. Casual contact in the workplace, for example, presents a lower risk than exposure by someone living in the same household.
Dr. Melby says TB disease presents the greatest risk to someone who is immunosuppressed, like those diagnosed with HIV or AIDS. Fortunately, with the advancements made in HIV treatment in recent years, TB disease among HIV patients has declined significantly since the mid-1990s.
Others who are immunosuppressed include patients prescribed TNF blockers for conditions like rheumatoid arthritis or Crohn’s disease. Because of this, TB screening is necessary before these patients begin an immunosuppressive medication regimen.
For a patient who has TB infection with no symptoms, a few treatment options are available. Dr. Melby says rifamycin-based drugs like Rifampin and Rifapentine are well-tolerated and are the first-line treatment for TB infection. Isoniazid (INH), once the standard treatment, is available as an alternative.
Individuals with TB disease may exhibit the typical symptoms of a respiratory infection, like a productive cough, but also chronic fever, weight loss, malaise, and even gastrointestinal issues. Patients with TB disease are treated with a combination of four drugs, due to the TB bacterium’s high rate of developing spontaneous drug resistance.
“If we treat with a single drug, there’s a reasonable likelihood that there are already some in the population of those bacteria that are resistant to that drug. So, when someone has TB disease, the standard is that we treat with multiple drugs to prevent the emergence of resistance,” he says.
Multidrug resistance is a major reason why TB disease continues to be a problem worldwide. In the U.S., this is most often seen among patients who have emigrated from locations with a high prevalence of multidrug resistance.
In addition to those with immunosuppression, TB poses a lesser, but still significant risk to individuals with weakened immune systems due to factors like diabetes, substance abuse, kidney disease, head and neck cancer, and organ transplant, among others.
“Something important for our clinicians to recognize is that diabetes is a risk factor for tuberculosis. We would have a lower threshold for investigating any symptoms in a patient with diabetes who was exposed to TB, especially if the diabetes is uncontrolled,” Dr. Melby says.
Dr. Melby notes that children who are infected, especially those under 1 year old, have a much higher risk of developing disease. Therefore, there is a much lower threshold for starting preventive medication in children.
TB screening is available at UTMB primary care and urgent care clinics and is typically performed through a blood test. The familiar TB skin test is still available, but not as widely used anymore, as Dr. Melby explains, because the blood test is easier to administer.
Primary care providers who see a patient with TB disease, or with TB infection and risk factors for developing disease, can send a referral to Infectious Disease (ID).
The ID Division has a clinic where patients are seen Monday through Friday on the Galveston campus and is planning to expand to League City in the near future.
 | Peter Melby, MD, serves as Professor and Director of the Division of Infectious Diseases in the Department of Internal Medicine at UTMB Health. The Infectious Disease clinic is located at the University Health Clinics building on the UTMB Galveston campus and sees patients Monday through Friday. |