Non-specific

• Pathogens


  Disease-causing organisms
• Non-specific defences


  Defences designed to prevent entry or limit the effect of any pathogen or foreign substance
• Homeostasis


  Defence maintains the body at its optimal level of functioning
• Communicable/transmissible/Infectious Disease


  Diseases that result from foreign organisms invading the body and multiplying there
• Contagious Diseases


  Diseases passed on to another person either by direct contact or by indirect contact with something that has been touched by another
• Vectors


  Intermediate hosts which transfer the pathogen from person to person
• Four major types of pathogens

  • Bacteria
  • Viruses
  • Fungi
  • Animal parasites
• Bacteria


  • Microscopic, unicellular, prokaryotic organisms (lack organelles including a nucleus, DNA floats freely in the cytoplasm or is in the form of small circular plasmids)
  • Single chromosome
  • Cell wall and membrane, some with slime capsule, flagella
• Bacteria can be seen with a light microscope
• Bacteria reproduce by binary fission
• Bacteria can be treated with antibiotics
• Most bacteria are harmless (non-pathogenic)
• Some bacteria are actually beneficial, e.g. cheese making
• Bacterial Infections


  Can be treated by antibiotics such as penicillin
• Bacteria cause disease in a number of ways, including through the production of toxins
• Toxin related diseases


  • Tetanus
  • Diphtheria
  • Bubonic plague
• Other bacterial diseases are caused by allergic reactions to the products of the bacterium, e.g. tuberculosis and rheumatic fever
• Viruses


  • Microscopic particles with genetic material DNA or RNA surrounded by a coat of protein or lipid envelope
  • Obligate intracellular parasites (cannot be grown outside of the cell)
  • Significantly smaller than bacteria
• Viruses infect living cells and cause them to manufacture more virus particles (intracellular replication)
• Viruses can be seen with an electron microscope
• Some drugs can control viral infections, but no drugs are known that can kill them
• Antibiotics cannot be used to treat viral infections
• Bacteriophages are viruses that multiply in bacterial cells, causing the death of bacteria
• Some viruses can be beneficial, such as bacteriophages used for insulin production
• Fungi


  • Can attack the tissues of humans and cause disease
  • Mould spores can cause mild to serious allergies in some people, such as sniffling, sneezing, and respiratory distress
• Ectoparasites


  Parasites which live on the outside of the body
• Endoparasites


  Parasites which live inside the body
• Endoparasites


  • Protozoans
  • Malaria
  • Tapeworms
  • Flukes
  • Amoeba
• Zoonoses


  Diseases that pass from animal to human
• Zoonoses


  • SARS
  • MERS
  • Bird flu
  • Zika
• Transmission of pathogens


  The spread of communicable disease brought about by the transfer of the pathogenic organism from one person to another
• Ways pathogens can be transmitted

  • Contact (physical, direct and indirect)
  • Body fluids
  • Droplets
  • Ingestion
  • Airborne transmission
  • Vectors
• Pathogens/diseases transmitted by direct contact

  • Skin infections
  • Some sexually transmitted diseases
• Pathogens/diseases transmitted by indirect contact

  • Plantar warts
  • Conjunctivitis
• Pathogens/diseases transmitted through body fluids

  • HIV
  • Hepatitis B and C
  • Glandular fever
• Pathogens/diseases transmitted through contaminated food and water

  • Food poisoning
  • Salmonella
  • Dysentery
  • Typhoid
• Endemic disease


  A disease that is always present in every country even if the number of cases is small
• Epidemic


  A disease outbreak where the number of cases increases to a much higher level than normal
• Pandemic


  A disease outbreak that spreads from one country to another
• Measures to keep Australia free of disease

  • Compulsory immunisation of newborns
  • Quarantine of plants, animals, and in some cases people arriving from countries where disease is prevalent
  • Notification of notifiable diseases
  • Health regulations for food preparation, storage, waste disposal and sanitation
  • Education on hygiene and disease prevention