Tuberculosis (TB): Symptoms, Causes & Treatment Guide

What Is Tuberculosis (TB)?

Tuberculosis is a bacterial infection caused by Mycobacterium tuberculosis that primarily attacks the lungs but can affect any organ in the body. It spreads through the air and is one of the world's top infectious disease killers, but is curable with proper antibiotic treatment lasting 6-9 months.

Tuberculosis, commonly known as TB, is an ancient disease that has affected humans for thousands of years and remains a major global health challenge today. The World Health Organization estimates that approximately 10.6 million people develop tuberculosis each year, and about one quarter of the world's population carries latent TB infection. Despite these concerning numbers, significant progress has been made in TB control, and the disease is both preventable and curable with modern medicine.

TB is caused by a slow-growing bacterium called Mycobacterium tuberculosis. When someone with active pulmonary TB coughs, sneezes, speaks, or sings, they release tiny infectious droplets into the air that can be inhaled by others nearby. However, not everyone who inhales TB bacteria becomes sick. In most cases, the immune system contains the bacteria, leading to what is called latent TB infection, where the bacteria remain dormant in the body without causing symptoms or spreading to others.

The distinction between latent TB infection and active TB disease is crucial for understanding tuberculosis. People with latent TB have no symptoms, feel completely healthy, and cannot spread TB to others. However, if their immune system becomes weakened - due to HIV infection, malnutrition, aging, or certain medications - the dormant bacteria can reactivate and cause active disease. Active TB causes symptoms, can be transmitted to others, and requires prompt treatment.

How common is tuberculosis?

Tuberculosis affects people in every country, though the burden of disease varies significantly by region. High-burden countries, primarily in Africa, Asia, and Eastern Europe, account for the majority of cases. Risk factors for developing TB include HIV infection, close contact with someone who has active TB, living in crowded conditions, malnutrition, and medical conditions or medications that weaken the immune system.

In high-income countries with robust public health systems, TB rates are relatively low but the disease has not been eliminated. Certain populations, including immigrants from high-burden countries, homeless individuals, and those with compromised immune systems, remain at elevated risk. Global efforts to end TB aim to reduce the disease burden by 90% by 2035 compared to 2015 levels.

What Are the Symptoms of Tuberculosis?

The classic symptoms of pulmonary tuberculosis include a persistent cough lasting more than 3 weeks, coughing up blood or sputum, night sweats, unexplained weight loss, fever, fatigue, and chest pain. Symptoms develop gradually and may be mild at first, which can delay diagnosis.

Tuberculosis symptoms develop gradually over weeks to months, which is why the disease is sometimes called the "great imitator" - it can mimic many other conditions. The symptoms of TB depend on which part of the body is affected, as TB can infect not only the lungs but also the lymph nodes, bones, kidneys, brain, and other organs. However, pulmonary (lung) TB is the most common form and the only form that is contagious.

In the early stages, TB symptoms may be mild and easily overlooked. Many people attribute their symptoms to other causes such as a persistent cold, smoking, or general fatigue. This delayed recognition can lead to prolonged illness and increased transmission to others. Understanding the characteristic symptom pattern is essential for early detection and treatment.

Pulmonary tuberculosis symptoms

When TB affects the lungs, which occurs in approximately 80% of cases, the following symptoms typically develop:

• Persistent cough: A cough lasting more than 3 weeks is the hallmark symptom. The cough may produce thick, discolored sputum (phlegm)
• Hemoptysis (coughing up blood): Blood-tinged sputum or coughing up blood can occur as the disease progresses
• Night sweats: Profuse sweating during sleep, sometimes requiring changing clothes or bedding
• Unexplained weight loss: Gradual, unintentional weight loss is common and gave rise to the historical name "consumption"
• Fever: Low-grade fever that may come and go, often worse in the evening
• Fatigue and weakness: Persistent tiredness and reduced energy levels
• Chest pain: Discomfort or pain when breathing or coughing
• Loss of appetite: Decreased interest in eating, contributing to weight loss

Extrapulmonary tuberculosis symptoms

TB can spread from the lungs to other parts of the body through the bloodstream or lymphatic system. When TB affects organs outside the lungs, it is called extrapulmonary TB. In addition to general symptoms like fever, weight loss, and fatigue, extrapulmonary TB causes symptoms specific to the affected organ:

Lymph node TB (tuberculous lymphadenitis): This is the most common form of extrapulmonary TB. It causes painless swelling of lymph nodes, most often in the neck region. The swollen nodes may gradually increase in size and can eventually drain through the skin if untreated.

Pleural TB: When TB affects the membrane surrounding the lungs (pleura), it causes chest pain that worsens with breathing, shortness of breath, and fluid accumulation around the lungs. This can make breathing difficult and is often accompanied by fever and general malaise.

Skeletal TB: TB can infect bones and joints, most commonly the spine (Pott's disease). Symptoms include localized pain, swelling, and sometimes deformity. Spinal TB can cause severe back pain and may lead to neurological complications if it compresses the spinal cord.

TB meningitis: When TB bacteria reach the membranes covering the brain and spinal cord, it causes tuberculous meningitis - a serious condition requiring immediate treatment. Symptoms include severe headache, stiff neck, confusion, sensitivity to light, and altered consciousness. TB meningitis is a medical emergency.

Symptoms in children

Tuberculosis in children can present differently than in adults. Young children, especially those under 5 years old, are at higher risk of developing severe forms of TB including TB meningitis and disseminated (widespread) TB. Children's symptoms are often less specific and may include prolonged fever, failure to thrive or gain weight, persistent cough, and general illness. Because children's symptoms can be subtle and children rarely produce sputum, diagnosing TB in children requires a high index of suspicion and often relies on exposure history and specialized testing.

What Causes Tuberculosis?

Tuberculosis is caused by the bacterium Mycobacterium tuberculosis, which spreads through the air when a person with active pulmonary TB coughs, sneezes, or speaks. Close, prolonged contact with an infectious person is usually necessary for transmission, and the bacteria cannot spread through casual contact or touching surfaces.

Understanding how tuberculosis develops and spreads is essential for prevention and control. TB is caused by bacteria belonging to the Mycobacterium tuberculosis complex, with M. tuberculosis being the primary species affecting humans. These bacteria have unique characteristics that make them particularly successful pathogens - they grow slowly, can survive for extended periods inside human cells, and have developed mechanisms to evade the immune system.

When someone with active pulmonary TB coughs, sneezes, laughs, sings, or even speaks, they release tiny droplets containing TB bacteria into the surrounding air. These microscopic droplet nuclei can remain suspended in the air for several hours, especially in enclosed spaces with poor ventilation. When another person inhales these infectious particles, the bacteria can reach the deepest parts of the lungs where infection begins.

Transmission and infection

Not everyone exposed to TB bacteria becomes infected, and not everyone who becomes infected develops active disease. The risk of infection depends on several factors:

• Duration of exposure: Longer time spent with an infectious person increases risk
• Proximity: Close contact in the same room or household carries higher risk than brief encounters
• Ventilation: Poorly ventilated, crowded spaces allow bacteria to accumulate in the air
• Infectiousness of the source: People with more bacteria in their sputum are more contagious
• Individual susceptibility: Immune status and genetic factors affect infection risk

Importantly, TB does not spread through shaking hands, sharing food or drink, touching bed linens or toilet seats, sharing toothbrushes, or kissing. The bacteria must be inhaled into the lungs to cause infection. This is why TB transmission typically occurs between people who spend extended time together, such as household members, close friends, or coworkers.

From infection to disease

When TB bacteria enter the lungs, the immune system mounts a response. In most healthy people, immune cells called macrophages contain the bacteria within structures called granulomas, effectively walling off the infection. This results in latent TB infection - the bacteria remain alive but dormant, causing no symptoms and posing no risk of transmission. About 5-10% of people with latent TB will develop active disease at some point in their lives, most commonly within the first two years after infection.

Certain factors significantly increase the risk of latent TB progressing to active disease:

• HIV infection: People living with HIV are 18 times more likely to develop active TB
• Recent TB infection: The first two years after infection carry the highest risk
• Immunosuppressive medications: Drugs for organ transplants, cancer, or autoimmune conditions
• Diabetes: Increases TB risk 2-3 times
• Chronic kidney disease: Particularly those on dialysis
• Malnutrition: Weakens immune defenses
• Silicosis: Occupational lung disease from dust exposure
• Very young or advanced age: Immune systems are less robust
• Substance abuse: Alcohol and drug use impair immunity

How Is Tuberculosis Diagnosed?

TB diagnosis involves multiple tests including chest X-rays, sputum microscopy, bacterial cultures, and molecular tests like GeneXpert. Blood tests (IGRAs) or skin tests (TST) detect TB infection but cannot distinguish between latent and active disease. Drug susceptibility testing is essential to guide treatment.

Diagnosing tuberculosis requires a combination of clinical assessment, imaging, and laboratory tests. No single test can definitively diagnose TB in all situations, so healthcare providers use multiple approaches based on the clinical presentation and available resources. Early and accurate diagnosis is crucial for effective treatment and preventing transmission.

Tests for TB infection

Two types of tests can detect TB infection - they show whether someone has been exposed to TB bacteria, but cannot distinguish between latent infection and active disease:

Tuberculin skin test (TST/Mantoux test): A small amount of purified protein from TB bacteria is injected just under the skin of the forearm. After 48-72 hours, a healthcare provider measures any reaction. A raised, hardened area indicates TB infection. However, the TST can give false-positive results in people who have received the BCG vaccine, which is used in many countries.

Interferon-gamma release assays (IGRAs): These blood tests measure the immune response to TB-specific proteins. IGRAs are more specific than TST and are not affected by prior BCG vaccination. They require only one visit and provide results within 24-48 hours. Common IGRA tests include QuantiFERON-TB Gold and T-SPOT.TB.

Tests for active TB disease

If TB infection is suspected, additional tests determine whether the person has active disease:

Chest X-ray: Imaging of the lungs can reveal characteristic patterns of TB infection, including infiltrates (patches of infection), cavities (holes in the lung tissue), and enlarged lymph nodes. While chest X-ray findings support a TB diagnosis, they are not definitive and must be confirmed with other tests.

Sputum smear microscopy: Examining sputum (mucus coughed up from the lungs) under a microscope can reveal TB bacteria if present in sufficient numbers. This relatively simple and inexpensive test provides results within hours but has limited sensitivity - it may miss cases with fewer bacteria.

Sputum culture: Growing TB bacteria from sputum samples in laboratory media is the gold standard for diagnosis. Cultures confirm the presence of viable bacteria and allow for drug susceptibility testing. However, because TB bacteria grow slowly, cultures can take 2-8 weeks to provide results.

Molecular tests (GeneXpert MTB/RIF): This rapid diagnostic test can detect TB bacteria and rifampicin resistance within 2 hours. GeneXpert has revolutionized TB diagnosis, particularly in high-burden settings, by providing quick, accurate results. It is now the initial diagnostic test recommended by WHO for anyone suspected of having TB.

Drug susceptibility testing

Testing TB bacteria for resistance to antibiotics is essential for selecting effective treatment. Drug-susceptible TB responds to standard first-line medications, while drug-resistant TB requires different, often longer, treatment regimens. Drug susceptibility testing can be performed through culture-based methods or rapid molecular tests.

How Is Tuberculosis Treated?

Standard TB treatment uses a combination of four antibiotics (isoniazid, rifampicin, pyrazinamide, ethambutol) for 6-9 months. Treatment has two phases: an intensive phase with all four drugs for 2 months, followed by a continuation phase with two drugs for 4-7 months. Completing the full course is essential to cure TB and prevent drug resistance.

Tuberculosis treatment has transformed a once-fatal disease into a curable condition. The key to successful treatment is using multiple antibiotics simultaneously for an extended period. This approach ensures all TB bacteria are eliminated and prevents the development of drug resistance. When treatment is taken correctly and completed in full, the cure rate for drug-susceptible TB exceeds 85%.

TB treatment follows established protocols developed by the World Health Organization and national health authorities. The specific regimen depends on whether the TB is drug-susceptible or drug-resistant, the location of disease in the body, and the patient's overall health status. Throughout treatment, patients are monitored for response to therapy and potential side effects.

Standard treatment for drug-susceptible TB

The standard treatment for drug-susceptible pulmonary TB consists of two phases:

Intensive phase (first 2 months): Patients take four antibiotics daily:

• Isoniazid (INH): Kills actively growing TB bacteria
• Rifampicin (RIF): A powerful antibiotic that colors urine and body fluids orange-red
• Pyrazinamid (PZA): Effective against dormant bacteria inside cells
• Ethambutol (EMB): Provides additional coverage while drug susceptibility results are pending

Continuation phase (4-7 months): After the intensive phase, treatment continues with two antibiotics:

• Isoniazid
• Rifampicin

Patients also receive vitamin B6 (pyridoxine) supplements to prevent nerve damage that can be caused by isoniazid. The total treatment duration is typically 6 months for uncomplicated pulmonary TB, though some situations require longer treatment.

Treatment for extrapulmonary and special situations

TB affecting sites outside the lungs generally responds to the same medication regimen, though treatment duration may vary. TB meningitis requires longer treatment (12 months) and may include corticosteroids to reduce inflammation. Bone and joint TB may need 9-12 months of treatment. Children receive the same medications as adults, with doses adjusted for body weight.

Treatment for latent TB infection

People with latent TB infection may receive preventive treatment to reduce their risk of developing active disease. This is particularly important for people at high risk, including those with HIV, recent TB contacts, and those taking immunosuppressive medications. Common regimens include:

• Isoniazid daily for 6-9 months
• Rifampicin daily for 4 months
• Isoniazid plus rifapentine weekly for 3 months (directly observed)

Managing side effects

TB medications can cause side effects, though most are manageable. Healthcare providers monitor patients throughout treatment and adjust medications if needed. Common side effects include:

• Gastrointestinal upset: Nausea, vomiting, and stomach discomfort, especially early in treatment
• Liver effects: Regular blood tests monitor liver function, as several TB drugs can affect the liver
• Orange-colored body fluids: Rifampicin causes urine, sweat, and tears to turn orange-red (harmless but important to know)
• Visual changes: Ethambutol can affect vision; eye exams may be needed
• Peripheral neuropathy: Tingling in hands and feet from isoniazid (prevented by B6 supplements)

Drug-resistant tuberculosis

Drug-resistant TB occurs when TB bacteria become resistant to one or more anti-TB drugs. The most concerning forms are:

• Rifampicin-resistant TB (RR-TB): Resistant to rifampicin, a key first-line drug
• Multidrug-resistant TB (MDR-TB): Resistant to at least isoniazid and rifampicin
• Extensively drug-resistant TB (XDR-TB): MDR-TB plus resistance to additional drugs

Treatment of drug-resistant TB requires specialized care, longer treatment duration (typically 18-24 months), and different medications with more side effects. New drugs like bedaquiline and delamanid have improved outcomes for drug-resistant TB, but prevention through proper treatment completion remains essential.

How Can Tuberculosis Be Prevented?

TB prevention includes BCG vaccination for children in high-burden countries, screening and treatment of latent TB infection in high-risk individuals, infection control measures, and prompt diagnosis and treatment of active cases. The most effective prevention is treating people with TB to stop transmission.

Preventing tuberculosis requires a multifaceted approach that addresses both individual protection and public health measures. While no intervention is 100% effective, combining multiple strategies significantly reduces TB transmission and disease development. Understanding prevention options helps individuals and communities take appropriate action.

BCG vaccination

The BCG (Bacillus Calmette-Guérin) vaccine is the only available vaccine against TB. It is made from a weakened strain of bovine tuberculosis bacteria. BCG vaccination is given to infants in countries with high TB burden and provides good protection against severe forms of childhood TB, including TB meningitis and disseminated TB.

However, BCG has important limitations. Its effectiveness against pulmonary TB in adults is variable and often limited. The vaccine does not prevent TB infection or reactivation of latent TB. BCG is generally not given in low-burden countries except to high-risk groups. New, more effective TB vaccines are under development but not yet available.

Treatment of latent TB infection

Treating latent TB infection prevents progression to active disease. This preventive treatment is recommended for people at high risk, including:

• Close contacts of someone with active TB
• People living with HIV
• Those taking immunosuppressive medications
• Healthcare workers with recent TB exposure
• People with certain medical conditions that increase TB risk

Infection control

Several measures reduce TB transmission in healthcare settings and communities:

• Respiratory isolation: People with suspected or confirmed infectious TB are isolated until no longer contagious
• Ventilation: Good airflow and natural ventilation reduce bacterial concentration in indoor air
• Respiratory protection: Healthcare workers wear N95 respirators when caring for TB patients
• Cough etiquette: People with respiratory symptoms should cover their mouths when coughing
• UV germicidal irradiation: Ultraviolet light can kill airborne TB bacteria in healthcare facilities

Early detection and treatment

The most effective way to prevent TB spread is to quickly identify and treat people with active disease. When someone with active pulmonary TB starts effective treatment, they typically become non-infectious within 2-3 weeks. This is why TB control programs emphasize early case finding, prompt diagnosis, and ensuring treatment completion.

When Should You Seek Medical Care for TB?

See a healthcare provider if you have a cough lasting more than 3 weeks, night sweats, unexplained weight loss, or fever, especially if you have been in contact with someone who has TB, have HIV, or live in or travel to high-burden areas. Seek immediate care for coughing up blood or severe symptoms.

Knowing when to seek medical attention for possible tuberculosis is important for both your health and preventing transmission to others. TB symptoms develop gradually, which sometimes delays people from seeking care. Being aware of the warning signs can lead to earlier diagnosis and better outcomes.

You should consult a healthcare provider if you experience:

• A cough that persists for more than 3 weeks
• Coughing up blood or blood-stained sputum
• Night sweats that drench your clothes or bedding
• Unexplained weight loss
• Persistent fever, especially if worse in the evening
• Unusual fatigue that doesn't improve with rest
• Chest pain or shortness of breath
• Swollen lymph nodes, particularly in the neck

These symptoms are especially concerning if you:

• Have been in close contact with someone diagnosed with TB
• Are living with HIV or have another condition that weakens the immune system
• Have traveled to or lived in a country with high TB rates
• Work in healthcare, correctional facilities, or homeless shelters
• Have previously had TB or latent TB infection

Frequently Asked Questions About Tuberculosis