chapter 4

• Infectious Disease


  Caused by infection of pathogens directly through mediums and vectors
• Infectious Disease


  • Tuberculosis
• Non-Infectious Disease


  Caused by genetic factors or lifestyle
• Non-Infectious Disease

  • Cancer
• Infectious Disease


  • The disease can be transmitted from one individual to another
• Non-Infectious Disease


  • The disease cannot be transmitted from one individual to another
• Types of Airborne Diseases

  • Droplet transmission
  • Dust transmission
• Prevention of Airborne Diseases

  1. Cover the mouth and nose when sneezing, coughing or yawning

  2. Do not spit everywhere

  3. Avoid being in a crowded place
• Airborne Diseases

  • Tuberculosis
  • Flu
  • Influenza A (H1N1)
• Waterborne Diseases


  Happens in an area with an inadequate water supply and poor sanitation
• Prevention of Waterborne Diseases

  1. Build toilets with good sanitation

  2. Boil drinking water properly

  3. Wash hands with soap after using the toilet
• Waterborne Diseases

  • Cholera
  • Typhoid
  • Amoebic dysentery
• Infection through contact


  Touching the infected skin or wearing the same clothes of an infected person will cause infections to occur
• Infection through vectors

  Animals that transmit these pathogens are called vectors
• Vectors

  • Cockroach - Salmonella typhi
  • Aedes mosquito - Dengue virus
• How Vectors Spread Diseases

  1. A fly that lands on dirt has pathogen on its legs and body

  2. The fly transmits the pathogens to the food

  3. The pathogens enter the body of the person who eats the contaminated food
• Stages of Prevention of Infectious Diseases

  • Primary stage - Improving health
  • Secondary stage - Determining transmission of infections through active and passive case detection
  • Tertiary stage - Controlling vector populations
• Body Defence System

  • Non-specific body defence mechanism
  • Specific body defence mechanism
• First Line of Defence

  • Skin - Prevents pathogens from entering the body
• Second Line of Defence

  • White blood cell - Fight pathogens through phagocytosis
• Third Line of Defence


  • Body immune system - Fights pathogens by producing antibodies
• Passive Immunity


  • Natural
  • Artificial
• Natural Passive Immunity


  Obtained when a baby receives antibody from breast milk or from mother's blood that flows across the placenta
• Natural Passive Immunity


  The immunity is temporary and short-lived
• Artificial Passive Immunity


  Obtained when an antiserum is injected into the patient's body
• Artificial Passive Immunity


  The antiserum fights against pathogens
• Artificial Passive Immunity


  The immunity is fast and temporary
• Active Immunity

  • Natural
  • Artificial
• Natural Active Immunity


  Occurs when a person recovers from an infection
• Natural Active Immunity


  The immunity lasts long after the infection
• Artificial Active Immunity


  Occurs when a vaccine that contains a dead or weakened pathogen is injected into the body and the immune system responds by producing antibodies
• Artificial Active Immunity


  The immunity lasts long after the infection
• Causes that weaken the immune system

  • Exposure to polluted air
  • Stress
  • Exposure to pesticides
• Practices that strengthen the immune system

  • Getting enough sleep or rest
  • Exercising and inhaling fresh air
  • Doing periodic health examination