Learn About Tuberculosis Prevention and Risk Reduction

Understanding Tuberculosis: What It Is and How It Spreads

Tuberculosis, commonly called TB, is an infectious disease caused by bacteria called Mycobacterium tuberculosis. According to the World Health Organization, tuberculosis remains one of the top infectious disease killers worldwide, with approximately 10 million people falling ill with TB each year. Understanding how this disease works is the first step toward protecting yourself and others.

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TB primarily attacks the lungs, which is why it's often called pulmonary tuberculosis. However, the bacteria can spread to other parts of the body, including the kidneys, spine, and brain. The disease spreads through the air when an infected person coughs, sneezes, or speaks. When someone with active TB releases respiratory droplets, people nearby can breathe in these bacteria and become infected.

An important distinction exists between TB infection and TB disease. A person can be infected with TB bacteria without showing any symptoms—this is called latent TB infection. The Centers for Disease Control and Prevention estimates that about one-quarter of the world's population has latent TB infection. People with latent TB cannot spread the disease to others, but they may develop active TB disease later in life if the infection is not treated.

Active TB disease develops when the immune system cannot control the TB bacteria, allowing them to multiply and damage lung tissue. Symptoms of active TB include a persistent cough lasting more than three weeks, chest pain, coughing up blood, fever, chills, and night sweats. The risk of progressing from latent TB infection to active disease is about 5-10% over a lifetime, though this risk is much higher for people with weakened immune systems.

Practical takeaway: Learning the difference between TB infection and TB disease helps you understand why screening matters even if you feel healthy, and why treatment of latent TB can prevent future illness.

Risk Factors That Increase Your Chances of Tuberculosis

Certain conditions and circumstances make some people more vulnerable to developing TB disease. Knowing your personal risk factors helps you take preventive steps and understand whether screening might benefit you. Risk factors fall into several categories: immunological factors, medical conditions, living situations, and occupational exposures.

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People living with HIV have the highest risk of developing TB disease if exposed to TB bacteria. HIV weakens the immune system, reducing the body's ability to fight TB infection. Studies show that people with HIV who have latent TB are 20-30 times more likely to develop active TB disease compared to people without HIV. Other conditions affecting immune function also increase risk, including diabetes, chronic kidney disease, and malnutrition. People taking immunosuppressant medications for conditions like rheumatoid arthritis or after organ transplants face elevated risk as well.

Medical history matters significantly in TB risk assessment. People who were infected with TB bacteria more recently—within the past two years—have a higher chance of developing active disease. People who had TB disease previously but were treated also face some risk of reactivation. Additionally, people who use injectable drugs have increased TB risk due to potential sharing of contaminated equipment and possible immunosuppression related to drug use.

Living and working conditions create opportunities for TB transmission. Crowded housing, homeless shelters, correctional facilities, and long-term care facilities have documented TB transmission clusters. Healthcare workers and others who work closely with TB patients face occupational risk. People from countries with high TB prevalence who have recently immigrated to lower-prevalence areas may carry latent TB infection acquired in their home countries. Close contacts of people with active TB disease have significant exposure risk.

Age groups show different risk patterns. Young children, especially those under five years old, have higher risk of progression to severe TB disease. Elderly people often have weaker immune function, increasing their risk. Teenagers and young adults also show increased incidence in some populations.

Practical takeaway: Identifying your personal risk factors helps determine whether TB screening would be valuable for you, even if you have no symptoms.

TB Screening and Testing: Who Should Be Tested

TB testing identifies both latent TB infection and active TB disease. Understanding the testing options and who benefits from screening helps people make informed decisions about their health. Two main types of TB tests are available: the tuberculin skin test (TST), also called the Mantoux test, and interferon-gamma release assays (IGRAs), which are blood tests.

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The tuberculin skin test involves injecting a small amount of purified protein derivative (PPD) into the skin of the forearm. A healthcare provider reads the test 48-72 hours later by measuring the size of any induration (raised area) that forms. The TST has been used for over a century and remains available and affordable. However, it requires two clinic visits and can produce false positives in people vaccinated with BCG vaccine, which is common in countries outside North America.

Interferon-gamma release assays measure the immune system's response to TB antigens by analyzing blood samples. These tests require only one clinic visit, produce results more quickly, and are not affected by BCG vaccination. However, IGRAs are more expensive than TST and may not be available in all settings. Some people show discordant results between TST and IGRA, requiring careful clinical interpretation.

The CDC recommends TB testing for specific groups. These include people with symptoms of active TB disease; people with latent TB infection risk factors; people with close contact to someone with active TB; healthcare workers; people living in congregate settings like correctional facilities or homeless shelters; people from countries with high TB prevalence; and people with medical conditions that increase TB risk, such as HIV or diabetes.

If someone tests positive for latent TB infection, additional testing may be needed to rule out active disease. This typically includes a chest X-ray to look for TB-characteristic patterns in the lungs and sometimes sputum tests to detect TB bacteria. A positive test for latent TB infection does not mean the person has TB disease—it means TB bacteria are present but inactive.

Practical takeaway: Understanding who should be tested and what different tests mean helps you determine whether screening is appropriate for your situation and what results indicate about your health status.

Treatment Options for Latent TB Infection

Treatment of latent TB infection prevents progression to active disease, protecting both individual health and community health. Several effective treatment regimens exist, and the choice depends on individual factors, drug interactions, and local TB program guidelines. The goal of treatment is to kill TB bacteria before they activate, preventing years of potential illness and transmission risk.

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The standard regimen for latent TB treatment is isoniazid (INH) taken daily for nine months. Isoniazid has been used since the 1950s and has a well-established safety record. Studies show that nine months of isoniazid reduces the risk of progression to active TB by approximately 60% in people with latent TB infection. This regimen is effective, relatively inexpensive, and works well for most people, though some experience side effects like peripheral neuropathy (nerve damage), which can be prevented by taking vitamin B6 supplements.

Shorter treatment regimens now offer alternatives. A four-month regimen using rifampin provides a shorter option for people who cannot tolerate isoniazid or who prefer a shorter treatment duration. A three-month regimen combining isoniazid and rifapentine (once-weekly dosing) offers convenience advantages and appears effective in clinical studies. This regimen has particular appeal for people who struggle with medication adherence since weekly dosing is easier to remember than daily dosing.

A two-month regimen using rifampin and pyrazinamide is no longer recommended due to concerns about hepatotoxicity and severe adverse events. Healthcare providers instead choose from the safer, more effective regimens listed above.

Medication side effects require monitoring during treatment. Common side effects include nausea, dizziness, and rash. Serious but rare side effects include liver damage (hepatitis) and peripheral neuropathy. People beginning latent TB treatment should receive baseline liver function tests and periodic monitoring. Alcohol use increases the risk of liver damage, so people in treatment should limit or avoid alcohol consumption.

Treatment completion rates matter significantly for success. Missing doses or stopping treatment early allows TB bacteria to survive and potentially develop drug resistance. Healthcare programs often use directly observed therapy (DOT), where a healthcare worker watches the patient take each dose, to improve completion rates. Some programs offer incentives like small gifts or food vouchers to support adherence.

Practical takeaway: Several treatment options exist for latent TB, and discussing options with a healthcare provider