Disease transmission basics

• Epidemic

  Sudden increase in cases in a wider area
• Pandemic

  Epidemic spread over countries or continents
• Outbreak


  Sudden increase in disease cases
• Infectious Agent


  The microbe causing the disease
• Virulence


  Ability of a microbe to grow and multiply
• Invasiveness


  Ability of a microbe to enter a host
• Pathogenicity


  Ability of a microbe to cause harm in a host
• Reservoir


  Where infectious agents normally grow and multiply
• Portal of Exit


  How a pathogen leaves its reservoir
• Mode of Transmission


  How an infectious agent is transmitted to a host
• Direct Transmission


  Infection through physical contact or airborne droplets
• Indirect Transmission


  Infection through utensils and surfaces
• Portal of Entry


  How a pathogen enters a susceptible host
• Susceptible Host


  Person at risk of infection
• Infectious Diseases


  Caused by pathogens and spread through various methods
• Non-infectious Diseases


  Not transmissible, caused by nutrition, immune, or environmental issues
• Vectors


  Carriers transmitting pathogens to other organisms
• First Line of Defence

  Prevents pathogen entry, innate immunity
• Second Line of Defence


  Internal responses after infection, innate immunity
• Third Line of Defence

  Immune system responses, adaptive immunity