Pulmonary tuberculosis (TB) is a serious, contagious infection primarily affecting the lungs, caused by the bacterium Mycobacterium tuberculosis (MTB).
Pulmonary TB, unlike latent TB infection, is an active disease where the bacteria multiply and cause inflammation and damage within the lungs. While typically localized to the lungs, pulmonary TB can spread through the bloodstream to other parts of the body, leading to extrapulmonary TB (TB affecting organs other than the lungs).
Key Aspects of Pulmonary TB:
- Cause: Infection with Mycobacterium tuberculosis (MTB).
- Primary Target: The lungs, although it can spread.
- Contagious Nature: Spread through airborne droplets when an infected person coughs, sneezes, speaks, or sings. Prolonged exposure is usually required for transmission.
- Symptoms: Common symptoms include a persistent cough (lasting 3 or more weeks), coughing up blood or sputum, chest pain, weakness or fatigue, weight loss, loss of appetite, chills, fever, and night sweats.
- Diagnosis: Diagnosis typically involves a medical history review, physical exam, tuberculin skin test (TST) or interferon-gamma release assay (IGRA) blood test, chest X-ray, and sputum tests (smear and culture) to identify the bacteria.
- Treatment: Pulmonary TB is treated with a course of antibiotics, typically lasting 6 to 9 months. The most common drugs used include isoniazid, rifampin, ethambutol, and pyrazinamide. Adherence to the treatment regimen is crucial to prevent drug resistance.
- Prevention: Preventative measures include vaccination with BCG (Bacille Calmette-Guérin) vaccine (although its effectiveness varies), identifying and treating latent TB infection, and infection control measures to limit the spread of airborne droplets.
Comparing Pulmonary TB to Latent TB Infection:
| Feature | Pulmonary TB (Active TB Disease) | Latent TB Infection |
|---|---|---|
| Bacteria | Active and multiplying | Inactive (dormant) |
| Symptoms | Present | Absent |
| Contagious | Yes | No |
| Chest X-ray | Usually abnormal | Usually normal |
| Sputum Tests | Usually positive | Negative |
| Requires Treatment | Yes | May require preventative treatment |
Risk Factors:
Individuals at higher risk of developing pulmonary TB include:
- People with weakened immune systems (e.g., HIV/AIDS, diabetes, those undergoing immunosuppressive therapy).
- People who have been recently infected with TB bacteria.
- Babies and young children.
- People who inject drugs.
- People who live or work in high-risk settings (e.g., prisons, homeless shelters).
- People who have immigrated from areas with high rates of TB.
In summary, pulmonary TB is a lung infection caused by Mycobacterium tuberculosis, characterized by active bacterial growth, symptoms, and the ability to spread to others. Early diagnosis and consistent adherence to treatment are critical for successful recovery and preventing further transmission.
