Tuberculosis affects people of all backgrounds, but certain groups face a significantly higher risk of both catching the infection and developing active disease. The distinction matters: about 5% of healthy adults who become infected will develop active TB within two years, and roughly 14% will over twenty years. But for people with weakened immune systems, the annual risk alone can reach 10%, making early awareness of risk factors genuinely lifesaving.
In 2023, TB reclaimed its position as the world’s leading infectious disease killer, surpassing COVID-19. Understanding who is most vulnerable helps explain why.
People Living With HIV
HIV is the single most powerful risk factor for developing active TB. The virus dismantles the same immune cells that keep TB bacteria in check, increasing the risk of a dormant TB infection reactivating by roughly 20-fold. For someone without HIV, the lifetime risk of a latent infection becoming active disease is around 5 to 10%. For someone living with HIV, that same level of risk plays out every single year.
HIV also increases the likelihood of drug-resistant TB. People living with HIV face about 1.4 times the risk of multidrug-resistant TB and 2.7 times the risk of primary drug resistance compared to HIV-negative individuals. During pregnancy, HIV increases active TB risk by about 2.5 times, compounding an already vulnerable period.
Young Children and Infants
Children under five are one of the most vulnerable groups. Their immune systems are still developing, which means they progress from infection to active disease faster than adults and are more likely to develop severe forms, including TB meningitis (infection in the brain) and miliary TB, where the bacteria spread to multiple organs. Because young children who test positive were almost certainly infected recently, they’re considered at especially high risk for rapid progression.
People With Diabetes
Diabetes roughly doubles the risk of developing active TB. A large Cochrane review covering tens of millions of participants found that people with diabetes were about 1.5 to 2.4 times more likely to develop TB disease than the general population. The connection is biological: poorly controlled blood sugar creates an environment that weakens the immune response, promotes inflammation, and gives TB bacteria a better foothold. As the global diabetes burden grows, this link is becoming a major public health concern, particularly in countries where both conditions are common.
People Who Smoke, Drink Heavily, or Use Drugs
Smoking, heavy alcohol use, and illicit drug use each independently raise the risk of both getting TB and having treatment fail once it starts. A recent meta-analysis found that alcohol consumption doubled the odds of treatment failure, smoking increased it by about 85%, and substance use doubled it as well. These aren’t small effects.
Smoking damages the lungs’ first line of defense, the tiny hairs and mucus that trap inhaled particles, making it easier for TB bacteria to establish an infection. Alcohol suppresses immune function broadly. Injection drug use adds risk both through immune suppression and through the social circumstances that often accompany it, including crowded living conditions and limited access to healthcare.
People in Crowded or Enclosed Settings
TB spreads through the air. Any setting where people spend prolonged time in close quarters with limited ventilation raises the odds of transmission. The CDC specifically flags several high-risk environments:
- Prisons and jails, where overcrowding and poor ventilation are common
- Homeless shelters, where transient populations make screening difficult
- Nursing homes and long-term care facilities, where elderly residents with weaker immune systems live in close proximity
- Hospitals and clinics, particularly in low-resource settings where isolation rooms and protective equipment may be unavailable
In some countries, TB and HIV patients share waiting rooms due to infrastructure limitations, further increasing cross-transmission. Cultural and language barriers between patients and staff can also undermine infection control efforts.
Healthcare Workers
TB is a recognized occupational hazard for healthcare workers, who face persistent contact with potentially infectious patients. The risk is highest in settings without adequate infection control: no isolation rooms, insufficient protective equipment, and clinics too understaffed to separate infectious patients from others. The CDC recommends that all U.S. healthcare personnel receive a baseline TB risk assessment, and that healthcare settings maintain a formal TB infection control plan.
People Born in or Traveling to High-Burden Countries
Geography is one of the strongest predictors of TB exposure. The CDC identifies people born in or who frequently travel to parts of Asia, Africa, and Latin America as higher risk, since TB transmission rates in these regions are far above those in the U.S. or Western Europe. Countries like India and South Africa carry particularly heavy burdens, including ongoing epidemics of extensively drug-resistant TB.
Someone who grew up in a high-burden country may carry a latent infection for years or decades without symptoms. If their immune system later weakens for any reason, that dormant infection can reactivate.
People on Immune-Suppressing Medications
Certain medications deliberately dial down the immune system, and that trade-off increases TB risk. This includes drugs used after organ transplants, treatments for autoimmune conditions like rheumatoid arthritis or Crohn’s disease, and some cancer therapies. The mechanism is straightforward: the same immune suppression that controls one condition also removes the body’s ability to keep TB bacteria contained.
Malnutrition and Poverty
Malnutrition weakens the immune system at a basic level, making it harder to fight off new infections and easier for latent ones to reactivate. Poverty amplifies nearly every other risk factor on this list. It correlates with crowded housing, limited access to healthcare, higher rates of HIV and diabetes, and greater exposure to indoor air pollution from cooking fuels, another recognized TB risk factor.
How To Know if You Should Get Tested
The CDC recommends TB testing for anyone in a higher-risk group but notes that testing is generally not needed for people with low risk. Two types of tests are available: a blood test, which measures immune response to TB proteins, and a skin test, which requires a return visit two to three days later to check for a reaction. The blood test is preferred for anyone who has received the TB vaccine (BCG), since the vaccine can cause a false positive on the skin test.
You fall into the testing category if you were born in or travel to countries where TB is common, live or work in group settings like shelters or correctional facilities, have spent time with someone who has active TB, or have any condition that weakens your immune system. People infected within the last two years are at the highest risk of rapid progression, which is why recent exposure is taken seriously even in otherwise healthy adults.