Immunology and disease

• Pathogenic organism


  An organism that has the ability to cause damage to a host
• Infectious disease


  A disease that can be transmitted between individuals
• Carrier


  An infected individual that is asymptomatic but can spread the disease
• Disease reservoir


  The environment (host) in which an infectious pathogen is found
• Endemic


  A disease that is ever-present in an area
• Epidemic


  A rapid rise in the incidence of a communicable disease at a local or national level
• Pandemic


  An epidemic that occurs worldwide, affecting a large number of individuals
• Vaccination


  The deliberate exposure of an individual to non-pathogenic forms, antigens or products of pathogens to provide artificial active immunity
• Antibiotic


  A chemical or compound produced by a living organism that kills or prevents the growth of bacteria
• Antigen


  A chemical present on the surface of a cell that induces an immune response
• Antibodies


  Immunoglobulins produced by B-lymphocytes in response to a specific antigen, triggering an immune response
• Antibiotic-resistant bacteria


  Bacteria that mutate to become resistant to an antibiotic, survive and reproduce very rapidly, passing on their antibiotic resistance
• Vector


  A living or non-living agent that transmits a pathogen between organisms
• Toxin


  A substance produced by a pathogen that causes damage to its host
• Antigenic types


  Organisms that possess the same or similar antigens on their surface, e.g. strains of a bacteria
• Identifying antigenic types


  Using antibodies from serum
• Host


  The organism from which a pathogen or parasite obtains nutrients and/or shelter
• Bacterial infections


  • Cholera
  • Tuberculosis
• Cholera


  A disease caused by strains of the Gram negative bacterium, Vibrio cholerae, the toxins of which cause severe diarrhoea leading to dehydration
• How cholera is spread

  1. Fecal/oral transmission

  2. Ingesting contaminated food or water
• How cholera is treated

  1. Rehydration (fluid and electrolytes)

  2. Antibiotics
• Tuberculosis


  A bacterial disease, caused by Mycobacterium tuberculosis and M. bovis, that damages lymph nodes in the lungs and neck, and weakens the immune system
• How tuberculosis is transmitted

  Airborne droplet transmission
• Methods of tuberculosis prevention and treatment

  1. Prevention - BCG vaccination of children

  2. Treatment - extensive course of antibiotics
• Viral infections


  • Influenza
  • Smallpox
• How influenza virus is transmitted

  1. Droplet infection

  2. Contact with contaminated surfaces
• Tissue affected by influenza

  Upper respiratory tract
• Symptoms of influenza


  Headache, coughing and sneezing, sore throat, vomiting, fever, muscular and joint pain. May cause secondary bacterial infections.
• How influenza is treated

  1. Quarantine

  2. Antiviral medication

  3. Antibiotics treat secondary bacterial infections

  4. Management of symptoms, e.g. painkillers
• Smallpox


  A disease caused by the virus Variola major that affects the skin and multiple other organs
• How smallpox is spread

  1. Droplet transmission

  2. Bodily fluids
• Symptoms of smallpox


  Symptoms include a headache, fever and pockmarking of the skin
• How smallpox has been eradicated

  Due to a successful vaccination program
• Properties of the smallpox virus that made its eradication possible

  • Little variation in antigens
  • Low rate of antigenic mutation
  • Immunogenic nature of antigens
  • No animal reservoir
• Protoctistan infection


  • Malaria
• Malarial parasite


  Plasmodium spp.