Transmission of communicable diseases

Question 1

Animals: Direct Transmission

Answer 1

• Where a pathogen is transferred directly from one affected organism to another.
  ​- Direct Contact: exchange of bodily fluids, skin-to-skin contact, from microorganisms in faeces on the hands etc.
• Inoculation: through a break in the skin or puncture wound, animal bites etc.
• Ingestion: taking in contaminated food or drink, transferring pathogens from hand to mouth etc.

Question 2

Animals: Indirect Transmission

Answer 2

• Where a pathogen travels from one infected individual to another through the means of an unaffected object or organism.
• Fomites: Objects such as bedding, socks and cosmetics etc.
• Droplet Infection: Minute droplets of saliva and mucus expelled when coughing, sneezing or talking etc.
• Vectors: Usually an unaffected organism which hosts the pathogen before transferring it.
• Water: Contaminated water can be classed as an inanimate vector of disease.

Question 3

Animals: Factors affecting transmission in animals

Answer 3

• Overcrowding and poor working/living conditions.
• Poor Nutrition.
• Compromised immune system as a result of another pathogen.
• Climate Change (changing climates mean different pathogens and vectors are able to survive in places they otherwise wouldn’t, where people have no immunity)
• Traditional medical practices and other cultural factors.
• Socioeconomic factors such as a lack of trained health workers or public warnings.
• Close contact between humans and animals (zoonoses)

Question 4

Plants: Direct Transmission

Answer 4

• Direct Contact: Where a healthy plant comes into contact with any part of a diseased plant.

Question 5

Plants: Indirect Transmission

Answer 5

• Soil Contamination: Pathogens or reproductive spores are often left in the soil, infecting the next crop. Also in composting.
• Vectors: Animals and humans can transfer spores from one plant to another by coming into contact, can also spread by feeding, aphids etc innoculate pathogen in directly etc.
• Wind and Water: Can be classed as vectors, carried on the wind, on the water’s surface, swim in water and contaminate plants it is used on.

Question 6

Plants: Factors Affecting Transmission in Plants

Answer 6

• Using crops strains which are susceptible.
• Overcrowding.
• Poor mineral nutrition.
• Damp, warm conditions increase pathogen’s chances of survival, reproduction and spread.
• Climate Change.

Question 7

Preventing spread of communicable disease in plants

Answer 7

• Leave room between plants to stop direct contact.
• Clear fields thoroughly to reduce all traces of plants.
• Rotate crops regularly so susceptible species are not always close to pathogen.
• Strict hygiene practices.
• Insecticides.