Tuberculosis: Transmission Diagnosis Treatment Challenges
What are the modes of transmission for tuberculosis (TB) and why is it a public health concern?, How is TB diagnosed and what are the key challenges in its treatment including drug-resistant TB?
Modes of Transmission and Public Health Concern
Tuberculosis (TB) is an airborne infectious disease caused by Mycobacterium tuberculosis. It spreads primarily through respiratory droplets when an infected individual coughs, sneezes, or talks. Prolonged exposure in crowded or poorly ventilated environments increases the risk of transmission. TB remains a major public health concern due to its high morbidity and mortality rates, particularly in low-resource settings. Additionally, latent TB infections (where the bacteria remain dormant) pose a challenge because they can reactivate under conditions of immune suppression, such as HIV infection.
Diagnosis of Tuberculosis
TB is diagnosed using a combination of clinical, radiological, and laboratory tests. The primary methods include:
- Tuberculin Skin Test (TST) – Also known as the Mantoux test, this detects prior exposure to M. tuberculosis. However, it cannot differentiate between latent and active infection.
- Interferon-Gamma Release Assays (IGRAs) – These blood tests measure the immune response to TB antigens and are useful for detecting latent TB, particularly in individuals with prior Bacillus Calmette-Guérin (BCG) vaccination.
- Sputum Smear Microscopy and Culture – Sputum samples are examined under a microscope for acid-fast bacilli (AFB) and cultured to confirm TB infection.
- GeneXpert (PCR Testing) – This molecular test detects TB DNA and rifampin resistance, allowing for rapid diagnosis and early identification of drug-resistant strains.
- Chest X-ray and CT Scans – Imaging helps identify pulmonary TB and assess lung damage.
Challenges in TB Treatment and Drug Resistance
TB treatment requires prolonged antibiotic therapy, typically involving a six-month regimen of isoniazid, rifampin, pyrazinamide, and ethambutol (first-line drugs). However, several challenges complicate treatment:
- Poor Adherence – Patients often stop treatment early, leading to incomplete bacterial eradication and increased drug resistance.
- Multidrug-Resistant TB (MDR-TB) – Strains resistant to isoniazid and rifampin require longer and more toxic second-line treatments.
- Extensively Drug-Resistant TB (XDR-TB) – This form resists both first-line and second-line drugs, making treatment options limited.
- Co-infections – TB-HIV co-infection worsens disease outcomes, requiring integrated care.
Strengthening public health measures, improving diagnostics, ensuring medication adherence, and developing new treatments are crucial to controlling TB globally. APA