Communicable Diseases

• Pathogen


  A microorganism that causes an infectious disease
• Communicable disease


  A disease that is caused by a pathogen and can be passed on
• Types of pathogens


  • Viruses
  • Bacteria
  • Protists
  • Fungi
• Ways diseases caused by pathogens can be spread

  • Airborne droplets
  • Water
  • Food
  • Direct contact
  • Vectors/animals
• Delay between infection and feeling ill

  Bacteria and viruses may reproduce rapidly inside the body
• Why viruses may cause more damage than bacteria

  Viruses live and reproduce inside cells, causing cell damage
• How bacteria may cause damage

  Bacteria may produce poisons (toxins) that damage tissues and make us feel ill
• Pathogen that causes measles

  A virus
• How measles virus is spread

  Inhalation of droplets from sneezes and coughs
• Why children are vaccinated against measles

  Measles can be fatal
• How measles is prevented

  By a vaccination
• How the spread of measles is reduced

  • Covering the mouth and nose with a hand/handkerchief when coughing or sneezing
  • Washing hands afterwards
  • Vaccination
• Pathogen that causes HIV

  A virus
• Initial symptoms of HIV infection
• Aim of antiretroviral drugs

  To stop the virus from replicating
• How HIV leads to AIDS

  When the body's immune system becomes so badly damaged it can no longer deal with other infections or cancers
• How HIV is spread

  Sexual contact or exchange of body fluids such as blood, which occurs when drug users share needles
• How the spread of HIV is reduced

  • Using condoms during sexual intercourse
  • Not sharing needles between people
• Pathogen that causes TMV

  A virus
• What is TMV and what type of organism does it affect

  A widespread plant pathogen affecting many species of plants including tomatoes
• Symptoms of TMV
• How the spread of TMV is reduced

  Remove affected leaves and burn them
• Pathogen that causes salmonella

  A bacteria
• How salmonella causes disease

  Spread by the bacteria being ingested in food, or on food prepared in unhygienic conditions
• Symptoms of salmonella
• How the spread of salmonella is controlled in the UK

  In the UK, poultry are vaccinated against Salmonella to control the spread
• How salmonella is treated

  By antibiotics
• Pathogen that causes gonorrhoea

  A bacteria
• How gonorrhoea is spread

  Gonorrhoea is spread by sexual contact
• How the spread of gonorrhoea can be controlled

  • Treatment with antibiotics
  • Use of a barrier method of contraception e.g. condoms
• Symptoms of gonorrhoea
• Issues with the treatment for gonorrhoea
• Pathogen that causes rose black spot

  A fungus
• What is rose black spot disease

  A fungal disease where purple or black spots develop on leaves, which often turn yellow and drop early
• How rose black spot is spread

  It is spread in the environment by water or wind
• How rose black spot affects a plant

  It affects the growth of the plant as photosynthesis is affected due to discolouration & destruction of the leaves
• How rose black spot can be treated

  Using fungicides and/or removing and destroying the affected leaves
• Pathogen that causes malaria

  A protist
• How malaria is spread

  Spread via mosquitoes
• How malaria is treated

  Anti-malarial drugs