Topic Overview

Respiratory Infections

1. Introduction

Definition

• Infectious diseases affecting the respiratory tract (upper or lower)

Key Concepts

Mode of Spread

• Airborne transmission
  • Infection spreads via droplet nuclei (<5 µm)
  • Remain suspended in air for long duration
  • Travel long distances
• Droplet transmission
  • Spread via respiratory droplets (>5 µm)
  • Travel short distance (~1 meter)
  • Settle quickly

Public Health Importance

• Major cause of:
  • Morbidity (common infections like URTI, influenza)
  • Mortality (pneumonia, TB, COVID-19)
• High transmission potential
  • Especially in crowded settings
  • Seasonal outbreaks common

🔥 Flowchart: Modes of Transmission (VERY IMPORTANT)

Respiratory Infection Transmission
│
├── Airborne
│ • Droplet nuclei (<5 µm)
│ • Long-distance spread
│ • Remains suspended
│ • Examples → TB, Measles
│
└── Droplet
• Larger droplets (>5 µm)
• Short-distance (~1 m)
• Settle quickly
• Examples → Influenza, COVID-19

🚀 Ultra High-Yield Points (NEET PG / MBBS)

• Airborne → long distance + suspended particles
• Droplet → short distance + heavy particles
• TB → classic airborne disease
• Measles → most infectious airborne disease
• Influenza → droplet spread

✅ Common Respiratory Infections ⭐

List of Important Diseases

• Tuberculosis (TB) ⭐
• Diphtheria ⭐
• Pertussis
• Measles ⭐
• Influenza
• COVID-19

🔥 Table: Disease vs Agent vs Transmission vs Vaccine (REVISION TABLE)

🚀 Ultra High-Yield Points (NEET PG / MBBS)

• TB & Measles → Airborne (very important MCQ)
• Diphtheria & Pertussis → Droplet spread
• BCG → TB prevention (partial protection)
• Pentavalent → Diphtheria + Pertussis + others
• COVID-19 → Mixed transmission (droplet + airborne)