Reducing and preventing the spread of disease

• Reducing or preventing the spread of disease in animals

  1. Being hygienic - basic hygiene measures (e.g. washing hands regularly to remove pathogens)

  2. Sterilising wounds in the skin - kills microorganisms (including pathogens) near the wound and stops them from entering the blood

  3. Living in sanitary conditions - having access to clean drinking water and a good system for disposing of sewage

  4. Destroying infected animals - infected animals may pass on the disease to other individuals

  5. Isolating infected individuals - prevents them from passing it on to anyone else

  6. Vaccination - vaccinating people and animals against communicable diseases

  7. The use of contraception - using condoms prevents sexually transmitted infections
• The initial cost to a society of creating sanitary conditions can be high
• Destroying infected animals is very costly and the disease may still spread if it is present in other individuals without symptoms
• Isolating infected individuals can be difficult for the infected person as they can't be with their loved ones - sometimes it can be difficult to balance the needs of an individual while doing what is best for society
• The spread of disease can be reduced or prevented in plants through:
• Plant diseases


  • Can reduce food sources for many organisms
  • Can damage habitats for other organisms in an ecosystem
• Regulating movement of plant material


  1. Makes sure that infected plants don't come into contact with healthy plants

  2. e.g. plant nurseries are not allowed to sell plants which have crown gall disease
• Destroying infected plants

  1. Stops them from being sources of infection

  2. Can be costly to a farmer
• Using sources of healthy seeds and plants


  Stops the disease from being introduced into a population
• Crop rotation


  1. Many pathogens are specific to a particular plant

  2. Changing the type of plants that are grown stops the pathogens from becoming established in an area

  3. May limit how profitable a farm is if it has to change farming practices for a different crop each year
• Polyculture (growing different types of plants in a single area at the same time)


  1. If a pathogen-specific to a single plant enters one plant, it's less likely to infect neighbouring plants because they are different species

  2. Limiting the spread of the pathogen through the crop
• Chemical control

  1. Fungicides can be used to kill fungal pathogens

  2. Can be an effective method

  3. May also lead to the evolution of resistant strains of the pathogen
• Biological control


  1. Another organism is used to control a pest or pathogen

  2. e.g. ladybirds eat aphids (an insect pest) so ladybirds can be released into an area to reduce aphid numbers

  3. The control organism may become a pest itself and cause more problems