March 24 is World Tuberculosis Day and the purpose is to provide information about its worldwide impact, prevention and treatment measures, and how we can spread awareness. Discussed below are some facts about tuberculosis that you may not be aware of, including causes of a false-positive TB test.
Having a TB Infection Doesn’t Necessarily Mean You Have TB Disease
People who test positive for tuberculosis without any signs or symptoms are known as having a non-transmittable latent tuberculosis infection. This means that they were exposed to TB at some point in their lives but 90 to 95 percent will not develop active TB disease. TB disease is the active form and can cause bloody mucus after coughing, fatigue, possible weight loss or fever, and shortness of breath.
Tuberculosis is the Leading Cause of Death Among People With HIV
It is the leading cause of death for people infected with HIV, accounting for one-fifth of all deaths. This patient population has a higher risk of death due to their weakened immune systems. It is recommended that people living with HIV get TB tests and take TB medications if necessary to prevent further complications.
The Lungs Aren’t the Only Organs Affected by TB
Although tuberculosis is found most commonly in the lungs, the TB-causing bacteria can travel through lymph nodes to other organs in the body such as the brain or kidneys. The bacteria can lay inactive or in its active state, can cause tissue death.
Tuberculosis Incidence Have Decreased Nationally But Certain States Are Seeing Increased Numbers of Reported Cases
In 2012, the United States saw a 5.4 percent decline in the number of reported cases of tuberculosis (3.2 reported cases for every 100,000 individuals). However, certain states have confirmed seeing increased rates of TB cases over the last year. The state of Washington has seen a 209 reported cases of tuberculosis in 2013 compared to 185 cases in 2012, resulting in a 13 percent increase.
False-Positive TB Tests Can Happen
The tuberculin skin test is done by injecting tuberculin purified protein derivative under the skin and the results read 48 to 72 hours later. They will look for an elevated area of skin at the site of injection and measure the diameter. Since the results are looked at by a health care provider, incorrect interpretation can occur and lead to a false-positive result. Other reasons for a false-positive test are incorrect administration, incorrect antigen used, and infection by nontuberculosis mycobacteria.