Communicable disease

• How can disease transmit through air?

  • Water droplets - coughing sneezing, fungi spores
• what types of disease spread through direct contact?

  • ie rabies, Hiv
• How can you prevent the transmittion of disease?

  • Air - cover your mouth, ventilate the area with fresh air
  • Direct contact - wash hands and any touched surfaces
  • Water - clean water through filters, or boil to kill pathogens
  • Vectors - insect repellent, bug injections
• What are pathogens?


  Microorganisms that can cause disease
• How do bacteria make us feel ill?

  • Release toxins which damage tissues
• How do viruses make us feel ill?

  • Reproduce inside cell, causing cell damage
• How do viruses reproduce?

  • Virus attaches to host cell
  • Genetic material is injected into the cell
  • virus DNA causes new viruses to be made inside cell
  • Host cell is split open, allowing the new viruses to leave cell and enter body
• What is measles?

  • Virus
  • Symptoms - red rash, fever
  • Prevention - Vaccines
  • Spreads - by air droplets ie sneezing or coughing
• What is HIV?


  • Virus (human immunodefficiancy virus)
  • Symptoms - initially causes a fever and tiredness. It then runs down your immune system meaning you are very prone to aids, cancer, and unusual disease
  • Prevent - protected sexual intercorse ie condom and don't share needles
  • Spreads by unprotected sex and sharing of insterile needles
  • Can also be treated with ANTIREOVIRAL DRUGS
• What is tobacco mosaic virus?

  • Virus in plants
  • Symptoms - mosaic pattern in leaves, discolouration
  • Causes stunt in growth due to discolouration of leaves and lack o chlorophyll for photosynthesis - no glucose
  • Prevention - destroy affected plants and sterilise any equipment that touched it
  • Transmitted through physical contact
• What is salmonella?


  • Bacteria
  • Symptoms - nausea, fever, chills, vomiting, cramps - caused by toxins of bacteria
  • Caused by ingesting bacteria commonly on raw chicken
  • Poultry are vaccinated against salmonella
• What is gonorrhea?


  • Effects reproductive organs
  • Bacteria
  • Symptoms - coloured discharge, pain when urinating
  • Can be treated with antibiotic penecillin
  • Spread by sexual contact - can be prevented by wearing protection
• What is black rose spot?

  • Fungal disease
  • Symptoms - purple or black spots on leaves - stunts growth as in tmv
  • Spreads via water or wind
  • Treated by fungacides or destroying the effected plant
• What is Malaria 


  • Protist - transferred by a vector - mosquito
  • Symptoms - episodes of fever, can be fatal
  • Prevent by using repellent spray, bug net, prevent the breeding of them by limiting this such as still surface water
• How is the skin a defence system?

  • Dosent allow pathogens to enter
  • Secretes oils and antimicrobial substaces which kill pathogens
• How does the nose act as a defence system?

  • Cilia and mucus trap pathogens
  • Cilia wofts the mucus and pathogens out of the nose
• How does the mouth defend against pathogens?

  • trachea contains cilia, mucus wofts pathogens to the stomach
• How does the stomach defend against pathogens?

  • hydrochloric acid burns/kills them
• What are the types of white blood cells?

  • Phagocytes
  • Lymphotcytes
• What is an antigen?

  • On the pathogen cell wall, which the WBC recognises as not part of the body
• What is phagocytosis?

  • Phagocyte is attracted to antigen
  • Phagocyte binds to the antigen
  • Englulfs pathogen
  • Digests pathogen
• What are antibodies?


  • Produced by lymphocytes - specific to an antigen
  • made of protein
  • Attach to antigen and attack pathogen
• What are antitoxins

  • Small particles which are produced by lymphocytes
  • Counteract toxins produced by pathogens which damage cells
• give ways a person should prevent the spread of bacteria to toher people

  • self isolate
  • wash hands after being sick or using toilet
  • dont prepare food for others
• give ways a farmer can prevemnt the spread of salmonella from his chickens

  • vaccinate them
  • give them antibiotics
  • dont sell infected chickens