Tuberculosis Revision Notes

Overview of Tuberculosis

• Classification of tuberculosis:
  • Pulmonary Tuberculosis
  • Extra-Pulmonary Tuberculosis
  • Bovine Tuberculosis (affects animal population)

Problem Statement

• Affects 1/3 of the world's population; 5-10% develop the disease.
• From 1 active tuberculosis patient, 10-15 individuals may be affected yearly.
• 8% of tuberculosis patients are also living with HIV/AIDS.
• 78% of tuberculosis patients in India are multi-drug resistant (compared to world average of 27%).
• India accounts for 26% of the global tuberculosis burden.
  • Other countries: Indonesia (8.5%), China (8.4%).
• Pediatric tuberculosis accounts for 10% of cases; 1 million cases globally, with 100,000 deaths from MDR and XDR tuberculosis.

Treatment Success Rates

• Overall treatment success rate in India: 85%.
• MDR tuberculosis treatment success rate: 57%.
• Treatment success rate for HIV-positive tuberculosis patients: 76%.

Social Factors Contributing to Transmission

• Malnutrition
• Overcrowding
• Economic recession
• Indoor air pollution
• Tobacco and alcohol consumption
• Diabetes

WHO Strategies for Tuberculosis Management

• Stop Tuberculosis Strategy (2006):
  • High-quality Dots expansion
  • Address drug resistance
  • Strengthen health systems
  • Engage private healthcare providers
• End Tuberculosis Strategy (2015):
  • Patient-centered care
  • Research and innovation
  • Ambitious goal: 95% reduction in cases and 90% reduction in incidence by 2035.
• Global 90-90-90 Targets:
  • 90% of all people with tuberculosis should receive appropriate therapy.
  • 90% coverage of vulnerable populations.
  • 90% treatment success rate for diagnosed individuals.

Statistics in India

• Incidence: 193 per 100,000.
• Treatment coverage: 82%.
• Case fatality rate: 177%.
• Multi-drug resistance incidence: 124 per 100,000.

Classification of Tuberculosis

• Based on anatomical site: Pulmonary or extrapulmonary.
• Based on HIV status: HIV positive or negative.
• Based on drug resistance:
  • Mono-resistant: Resistance to one first-line drug.
  • Poly-drug resistant: Resistance to more than one first-line drug.
  • Multi-drug resistant (MDR): Resistance to at least isoniazid and rifampicin.
  • Extensive drug resistance (XDR): Resistance to any fluoroquinolone and at least one of the three injectable second-line drugs.
• Previous treatment history: New, relapse, treatment after failure, or loss to follow-up.

Causative Agent

• Mycobacterium tuberculosis: Major cause of tuberculosis.
• Atypical mycobacteria: Include species like M. avium, M. kansasii.

Transmission of Tuberculosis

• Primarily through coughing.
• Not transmitted by fomites.
• Incubation period: 3-6 weeks from infection to positive tuberculin test.

Control of Tuberculosis

• Curative Components:
  • Case finding and treatment.
• Preventive Components:
  • BCG vaccination.

Case Finding Strategies

• Active Case Finding: Screening high-risk populations.
• Passive Case Finding: Patients presenting with symptoms.
• Community and Institutional Screening.

Diagnostic Tools

• Microscopy and Culture.
• Drug Sensitivity Testing: Rapid molecular tests preferred for speed and accuracy.
• Tuberculin Test: Uses PPD RD23 with TW 80; positive if >10mm.

Treatment of Tuberculosis

• First-Line Drugs:
  • Bactericidal: Rifampicin, Isoniazid.
  • Bacteriostatic: Ethambutol.
  • Side effects include hepatotoxicity, peripheral neuropathy.
• Second-Line Drugs:
  • Include fluoroquinolones and injectable drugs (Streptomycin).
  • Newer drugs like Bedaquiline for MDR tuberculosis.

Approaches to Control

• Short-course chemotherapy (DOTS): Directly observed treatment.
• Daily dose regimen introduced to replace intermittent doses.

Special Considerations

• Childhood tuberculosis: Screening for persistent symptoms.
• Tuberculosis in pregnancy: Treatment adjusted based on gestational age.
• Co-infections: TB with HIV and COVID-19.

Conclusion

• Comprehensive understanding at the undergraduate level is sufficient to answer exam questions.
• Emphasis on concise knowledge rather than 36-page references.