What is tuberculosis?

Before antibiotics, tuberculosis (TB) claimed nearly one billion lives in the 19th and 20th centuries. Known by many names throughout history, including “consumption,” “phthisis” and the “white plague,” TB remains a global public health problem. Today, tuberculosis is the 13th leading cause of death worldwide and the second most infectious and fatal disease after COVID-19.

In San Diego County, the number of TB cases began decreasing in the early 1990s. However, 243 cases of TB were reported in the county in 2023, an increase of about 17% from 2022.

While the disease is less common than it once was, it’s important to understand what TB is, how it spreads, and how to protect yourself and your family.

How TB spreads
Tuberculosis is a bacterial infection that primarily affects the lungs. It is spread through the air when an infected person coughs, talks or sneezes.

According to Dr. Ariella Goldblatt, an infectious disease specialist with Sharp-Rees Stealy Medical Group, TB is transmitted through airborne particles, similar to how COVID-19 spreads. “The disease can easily spread when someone who is infected coughs, and the microscopic particles containing the bacteria are inhaled by another person,” she says.

Latent TB vs. active TB infection
A tuberculosis infection doesn’t always mean you’ll get sick. There are two forms of the disease:

• Latent TB: In a latent TB infection, the bacteria in the body are inactive. There are no symptoms, and the disease is not contagious. “The bacteria infect the lungs, but the body's immune system is able to wall off the bacteria and prevent it from growing or causing symptoms,” says Dr. Goldblatt.
  
  In some people, especially those who have a weak immune system, the bacteria can become active and cause TB disease. Approximately 175,000 San Diego County residents have latent TB, the region's Health and Human Service Agency reports.
  

• Active TB: People with active TB, also called TB disease, can spread the disease and develop symptoms.
  
  “The symptoms of active pulmonary TB include a cough lasting longer than three weeks, coughing up blood or phlegm, chest pain, fevers, chills, night sweats and unintentional weight loss,” Dr. Goldblatt says.

TB risk factors
Anyone who comes into contact with a person who has active TB is at risk for infection. There are also certain medical and lifestyle factors associated with an increased risk of developing TB.

People who are immunocompromised, such as infants and the elderly, or those who have weakened immune systems from chronic medical conditions or medications have a higher risk of developing active TB disease, Dr. Goldblatt says. People who live or work in high-risk settings, such as correctional facilities, nursing homes and homeless shelters, also face an increased risk.

Treating and preventing TB
The treatment of tuberculosis usually involves taking antibiotics for several months. Receiving treatment for a latent TB infection significantly reduces the likelihood of it turning into an active infection. If left untreated, TB disease can cause death.

“A key part of tuberculosis prevention is screening those at risk for latent TB and treating them to prevent active TB in the future,” Dr. Goldblatt says. 

The only licensed tuberculosis vaccine, the Bacille Calmette-Guérin (BCG) vaccine, was developed more than 100 years ago. The vaccine is not widely used in the U.S. due to low TB rates and low risk of infection. It’s often given to infants and young children in countries where TB is more common.

“The vaccine prevents severe disease in children, such as TB meningitis,” Dr. Goldblatt explains. “But it’s not effective at preventing pulmonary TB and its protection wanes over time.”

Thanks to modern medicine and general improvements in health and hygiene, there have been drastic reductions in tuberculosis cases in the last century. In the U.S., TB can almost always be treated and cured.

Keeping your immune system healthy and avoiding exposure to someone with active TB is the best way to prevent an infection. Talk with your doctor if you have concerns about a possible TB exposure or your risk of infection.

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