Tuberculosis: Prevention & Global Impact

RES 301: Prevention of TB

• TB prevention lecture, presented by Dr. Mohammed Abdulrazzaq, on February 9, 2025
• The lecture covered ethics of TB prevention, global TB strategy, levels of prevention, and prevention of infectious diseases.
• Learning outcomes included assessing factors influencing successful TB prevention and differentiating between prevention levels.

History of TB

• 1882: Koch identified TB bacilli
• 1907: Tuberculin skin test developed (von Pirquet)
• 1919: BCG vaccine introduced (Bacille Calmette-Guérin)
• 1943: Schatz and Waksman discovered streptomycin
• 1948: BMRC trial of streptomycin vs. bed rest
• 1952: Isoniazid developed
• 1966: Rifampicin developed
• 1978: Short course chemotherapy (DOTS) introduced

Global TB Strategy (Post-2015)

• Vision: A TB-free world (zero deaths, disease, and suffering)
• Goal: End the global tuberculosis epidemic
• Milestones for 2025: 75% reduction in TB deaths, 50% reduction in incidence (less than 55 cases per 100,000 population), no affected families facing catastrophic costs
• Targets for 2035: 95% reduction in TB deaths, 90% reduction in incidence (less than 10 cases per 100,000 population), no affected families facing catastrophic costs

Principles of Post-2015 Global TB Strategy

• Government stewardship and accountability with monitoring and evaluation
• Strong coalition with civil society organizations and communities
• Protection and promotion of human rights, ethics, and equity
• Adaptation of strategy and targets at the country level with global collaboration

Disease Prevention and Control

• Weak points within a disease need to be identified and the weakest links in transmission broken
• Sound epidemiologic knowledge is required. This includes natural history, time/place/person distribution, multifactorial causation, sources of infection, and disease transmission dynamics.

Prevention: Definition and Concept

• Actions aimed at eradicating, eliminating, or minimizing the impact of disease and disability
• In the modern-day, prevention is broad-based, encompassing primordial, primary, secondary, and tertiary prevention levels.

Primordial Prevention

• Aims to prevent the emergence of risk factors, such as behavioral, environmental, economic, social conditions that may negatively affect health.
• Includes improving living conditions, boosting good nutrition, education/awareness initiatives, reinforcing healthcare infrastructure, and preventing migration to high-risk areas.

Primary Prevention

• Actions taken prior to the onset of disease, preventing it from occurring altogether.
• Includes health promotion measures to improve health outcomes.
• Includes specific protection measures such as immunization, chemoprophylaxis, exposure control, and nutritional considerations for vulnerable populations.

Secondary Prevention

• Halts disease progression early and avoids complications
• Early diagnosis (screening), proper case identification, and adequate treatment are key components.
• This level aids in preventing both immediate complications and further transmission to others.

Tertiary Prevention

• Aimed at minimizing impairments and disabilities.
• Focuses on rehabilitation and adaptation to irremediable conditions after a disease process has progressed beyond its early stages.
• Tertiary measures prevent further complications, long-term disability, social limitations, and loss of quality of life.

TB in Weakened Persons

• Vulnerable individuals (HIV, diabetes, poor nutrition, cancer treatments, steroid use, drug use, smoking, and older age) are more susceptible to TB infection.
• Priority for individuals with compromised immune systems may include prophylactic antibiotics.

Examples of TB Prevention Levels

• Vaccination (e.g., BCG) for newborns (primary)
• Screening/early treatment of active TB (secondary)
• Occupational/social rehabilitation for advanced TB (tertiary)

Intervention to Break the Cycle of Infection

• This involves actions to curb the disease process at multiple points within its life cycle (e.g., surveillance, disinfection, isolation of cases/carriers, observation of contacts, etc).

Control of Infectious Diseases (“4 C's”)

• Diagnosis
• Notification
• Isolation
• Disinfection
• Treatment
• Follow-up
• Release
• Observation
• Quarantine
• Detection of carriers in the community
• Community Epidemiological investigations and containment

Disease Elimination and Eradication

• Elimination stops transmission within a region or area.
• Eradication eliminates the disease globally.
• Eradication of disease is a significant step toward halting its continued spread within a population and in future populations.

References

• Park’s Textbook of Preventive and Social Medicine, 25th ed
• WHO: Global strategy and targets for tuberculosis prevention, care and control after 2015 (2015)