Communicable and non diseases

• What is a pathogen?

  A microorganisms that causes disease
• Pathogens are microorganisms that can cause disease. Are these diseases classed as communicable or non-communicable diseases? 

  communicable diseases
• Four main ways that pathogen can spread:

  1. Through the air
  2. Contaminated food
  3. contaminated water
  4. Direct contact
• How can pathogen spread by air?

  Diseases such as influenza and measles can spread via tiny droplets of saliva that we expel when we cough or sneeze.
• How can pathogens spread by contaminated water?

  Diseases such as cholera can spread through water sources contaminated by the diarrhoea of infected people. 
• How can pathogens spread through contaminated food?

  Diseases such as salmonella are spread by eating food which has been infected with salmonella, and then not cooked properly.
• How can pathogens spread through direct contact?

  Athlete's foot is spread by walking barefoot on surfaces contaminated with the fungi. 
• Give 4 ways we can reduce the spread of infectious disease

  1. Improved hygiene such as washing hands
  2. Vaccination
  3. Killing vectors that carry pathogens
  4. isolating people who are infected
• Microorganisms are a group of tiny organisms

  1. Bacteria
  2. viruses
  3. protist
  4. fungi
• Non-communicable diseases


  Diseases that can’t be spread such as cancer
• Communicable disease


  Diseases that spread from person to person which affect both animals and plants
• Viruses


  • Not cells, not living, but considered organisms
  • About 10,000 times smaller than animal cells
  • Can't reproduce by themselves, but can use a host cell's machinery to make copies of themselves
  • Can burst the host cell to release new viruses
• Viruses colonizing and bursting host cells


  Damages the body and makes us feel ill
• Viral diseases covered


  • Measles
  • HIV
  • Tobacco mosaic virus
• Measles virus


  • Spread by droplets when an infected person coughs or sneezes
  • Causes a red rash and fever
  • Rare in UK due to vaccination
• HIV


  • Human Immunodeficiency Virus
  • Spreads through sexual contact or sharing bodily fluids
  • Causes a deficient immune system
  • Initially causes flu-like symptoms(e.g. fever and tiredness)then weakens the immune system over time
  • Can develop into AIDS if left untreated
  • Treatable with antiretroviral drugs(prevent viruses from replicating in our body)
• Tobacco mosaic virus (TMV)


  • Affects plants, not humans
  • Causes discolored patches on leaves, reducing photosynthesis and plant growth
• Viruses are quite hard to explain as they aren't cells and aren't living, but we still consider them to be organisms
• Most bacteria don't have anything to do with humans, and the ones that do actually help us
• There are trillions of bacteria in your intestines right now helping you break down your dinner
• Bacteria


  Single-celled organisms about 100 times smaller than our own cells
• Bacteria can replicate rapidly within our bodies because of the good food supply
• Bacteria


  They might produce toxins which make us feel ill by damaging our cells and tissues
• Bacterial disease


  • Salmonella
• Salmonella causes food poisoning and we can catch it from any food that has been contaminated with the bacteria, most often by eating chicken that caught the disease
• In the UK, most chickens have to be vaccinated against salmonella, so it's relatively rare
• Symptoms of salmonella


  • Fever
  • Stomach cramps
  • Vomiting
  • Diarrhea
• Salmonella generally passes by itself within a week, and people just need to stay well hydrated and have a sick bowl close by
• Bacterial disease 2

  • Gonorrhea
• Gonorrhea


  A sexually transmitted disease (STD) passed on through sexual contact, for example having unprotected sex
• Symptoms of gonorrhea


  • Pain when urinating
  • Thick yellow-green discharge from the vagina or penis
• We used to use a common antibiotic penicillin to treat gonorrhea, but now a lot of gonorrhea strains are resistant to penicillin, so we're using rarer and more expensive antibiotics
• The best prevention for gonorrhea is avoiding unsafe sex and using barrier methods of contraception like condoms