12.3 Transmission Of Communicable Diseases

Question 1

Two main types of disease transmission

Answer 1

Direct

Indirect

Question 2

Direct transmission

Answer 2

Pathogen is transferred directly from one individual to another by:
Direct contact
Inoculation
Ingestion

Question 3

Direct contact

Answer 3

Kissing or contact of bodily fluids of person
Direct skin to skin contact
Microorganisms from faeces transmitted on the hands

Question 4

Inoculation

Answer 4

Through a break in the skin
From an animal bite
Through a puncture wound or through sharing needles

Question 5

Ingestion

Answer 5

Taking in contaminated food or drink

Transferring pathogens to the mouth from the hands

Question 6

Indirect transmission

Answer 6

Pathogen travels from one individual to another indirectly by
Fomites
Droplet infection
Vectors

Question 7

Fomites

Answer 7

Inanimate objects such as bedding, socks, can transfer pathogens

Question 8

Droplet infection

Answer 8

Droplets containing pathogens are released during talking, coughing, sneezing
If healthy individuals breathe this in, they could become infected

Question 9

Vector

Answer 9

Transmits communicable pathogens from one host to another

Eg - insects and water

Question 10

Transmission between animals and humans

Answer 10

Some communicable diseases can be passed from animals to people
Minimise close contact with animals and washing hands thoroughly can reduce spread
Sometimes humans can act as vectors for animal diseases like foot and mouth disease

Question 11

Factors that increase probability of catching a communicable disease

Answer 11

Overcrowded living and working conditions
Poor nutrition
Compromised immune system
Poor disposal of waste (breeding site for vectors)
Climate change - introduce new vectors and diseases
Culture and infrastructure
Socioeconomic factors - lack of trained health workers and insufficient public warning if there is an outbreak of disease

Question 12

Direct transmission of plant diseases

Answer 12

Direct contact of a healthy plant with any part of a diseased plant

Question 13

Soil contamination

Answer 13

Infected plants leave pathogens or reproductive spores from Protocista or fungi in the soil
They survive the composting process, so infection cycle can be completed when contaminated compost is used
These can infect the next crop

Question 14

Vectors in plants

Answer 14

Wind - spores can be carried in the wind
Water - spores swim in the surface film of water on leaves, rain splashes carry pathogens and spores
Animals - insects and birds carry pathogens and spores from one plant to another
Humans - transmitted by hands, clothing, equipment, fomites and by transporting plants around the world

Question 15

Factors that increase transmission of disease in plants

Answer 15

Planting varieties of crops that are susceptible to disease
Overcrowding
Poor mineral nutrition
Damp, warm conditions increase survival of pathogens
Climate change - increased rainfall and wind promote spread of disease, can spread to new areas

Question 16

How to reduce spread of disease in plants

Answer 16

Leave room between plants
Clear fields throughly after harvest
Rotate crops - spores or bacteria will eventually die without access to host plant
Strict hygiene - wash hands, sterilise equipment
Control insect vectors