12.3 The Transmission Of Communicable Diseases

Question 1

Examples of direct transmission of pathogens between animals

Answer 1

• direct contact (e.g. kissing or contact with body fluids of another person, direct skin to skin contact, microorganisms from faeces transmitted on the hands)
• inoculation (through a break in the skin, from an animal bite, through a puncture wound or through sharing needles)
• ingestion (taking in contaminated food or or drink or transferring pathogens to the mouth from the hands)

Question 2

Examples of indirect transmission of pathogens between animals

Answer 2

• fomites (inanimate objects such as bedding, socks or cosmetics)
• droplet infection (droplets of saliva and mucus expelled from your mouth e.g. when you sneeze could contain pathogens)
• vectors (transfers communicable diseases from one host to another) e.g. mosquitos transmit malaria
• water can also act as a vector of disease

Question 3

Factors that affect the transmission of communicable diseases in animals

Answer 3

• overcrowded living and working conditions
• poor nutrition
• a compromise immune system (e.g. having HIV/ AIDS, or having to take immunosuppressant drugs after surgery)
• poor disposal of waste, providing breeding sites for vectors
• climate change which can introduce new vectors and diseases
• culture and infrastructure (e.g. in developing countries traditional medical tactics can increase transmission)
• socioeconomic factors (e.g. lack of trained health workers, lack of education)

Question 4

Examples of indirect transmission of pathogens between plants

Answer 4

• soil contamination
• vectors (e.g. the wind can carry fungal spores over large distances, water, animals like insects e.g. aphids, humans transmit pathogens onto plant by hands, clothing, fomites)

Question 5

What factors affect the transmission of communicable diseases in plants?

Answer 5

• planting varieties of crops that are susceptible to disease
• over-crowding increases likelihood of contact
• poor mineral nutrition reduces resistance of plants
• damp, warm conditions increase the survival and spread of pathogens and spores
• climate change

Question 6

How to prevent the spread of communicable diseases in humans?

Answer 6

• hand washing
• improvement in living and working conditions (e.g. ensuring good nutrition and reducing overcrowding)
• disposal of both bodily and household waste effectively

Question 7

How to prevent spread of communicable diseases in plants?

Answer 7

• leave plenty of rooms between plants
• clear fields (remove all traces of plants from the soil at harvesting)
• rotate crops
• follow strict hygiene practices
• control insect vectors