
Modern screening tools like blood tests and chest X-rays make it easy to detect and treat latent TB before it becomes contagious or life-threatening.
Some diseases seem so unfamiliar to people today that they may mistake them for not being an issue in today’s age. Tuberculosis (TB) serves as a good case in point. A century ago, the disease would have been very familiar to most Americans. In 1945, there were about 115,000 new cases and 63,000 deaths from TB each year in the United States. By contrast only 9,615 cases were reported in 2023.
Causes, Transmission, and Symptoms
Tuberculosis is a bacterial infection caused by Mycobacterium tuberculosis. The bacteria spreads when someone who is infected coughs or sneezes, causing it to be present in the air. If someone else breathes in the infected air, they can get infected in their lungs.
Once TB enters the lung, most people will not get sick, since their body is able to mount an immune response and contain it from spreading. This is called a latent TB infection; the individual has no symptoms and cannot spread it to others at this time. This small pocket of bacteria that has been walled off by the immune system can then reactivate at times when the person has a weakened immune system. This now becomes an active TB infection that can make the person sick and also be transmitted to others.
Active TB infection in the lung (pulmonary TB) can cause fevers, night sweats, fatigue, weight loss, and cough, with symptoms becoming chronic with time. If untreated, TB can lead to death in a variable amount of time through its complications. Some people are at higher risk of developing active TB infections. These include the young, elderly and those with immune systems weakened by diseases like HIV and diabetes or by taking medications that can lower immunity.
Around 5-10 percent of immunocompetent people with latent TB infections will progress to active infections over a person’s lifetime if left untreated. Fortunately, it is easy to diagnose a latent TB infection – and to access treatment that prevents such progression.
Testing and Treatment
There are different tests available to detect latent TB, including skin tests and blood tests. The skin test, also called Tuberculin skin test or TST, involves getting a small injection of harmless TB material in the skin. The patient then returns in 48 hours to have the site examined. If a person has TB, there is induration (a hardened or thickened area) of surrounding skin that can then be reported in millimeters. Given this is cumbersome, many people prefer the blood test. The Interferon gamma release assay (IGRA) detects the release of interferon-gamma from immune cells after stimulation with materials from the TB bacteria. If the IGRA test is reactive, a simple chest X-ray can help differentiate active versus latent TB.
Learning of latent TB infection is the easiest way to access treatment that can prevent its conversion to active TB. Treatment of latent TB infection may involve several types of medicines and take three to nine months, depending on the treatment plan.
Should You Be Screened for TB?
Given the low prevalence of TB, not everyone needs screening. Talk to your healthcare provider to learn more about whether you need any screening. Should your group require it, Primary.Health can provide easy, accessible large-scale testing for latent TB and other infectious diseases as well as vaccinations and boosters. Reach out to our diagnostics team to learn more.
Disclaimer: This blog content and linked materials are not intended as individual medical advice, diagnosis, or treatment, and should not be considered as such. Any readers with medical concerns should contact a licensed healthcare provider. This blog is provided for informational purposes only.