12.3 : Transmision of Communicable Diseases

Question 1

Give examples of direct transmission

Answer 1

Direct contact e.g. kissing, skin-to-skin contact, sexual intercourse

Inoculation e.g break in skin, animal bites, puncture wound / sharing needles

Ingestion e.g. contaminated food and drink, transferring pathogens to mouth from hands

Question 2

What is direct transmission ? What diseases spread like this?

Answer 2

Pathogen is transmitted directly from one organism to the other.

HIV - sex
Athletes foot - touch

Question 3

What is indirect transmission? What diseases spread like this?

Answer 3

Pathogen travels from one individual to another indirectly ( using an intermediate )

Late blight is spread when spores are carried between plants ( air and then water )

Malaria is press via mosquitoes which act as vectors

Question 4

Give examples of indirect transmission

Answer 4

Fomites e.g. inanimate objects like bedding or cosmetics can transfer pathogens

Droplet infection ( inhalation) e.g. saliva and mucus expelled when coughing or sneezing. Healthy people breathe this.

Vectors - transmits pathogens from one host to another. Animals can be vectors, but so can water

Question 5

What factors affect transmission of communicable diseases in animals?

Answer 5

Overcrowded living and working conditions

Poor nutrition

Compromised immune system

Climate change

Culture and infrastructure

Socioeconomic factors

Question 6

What factors affect transmission of communicable diseases in plants?

Answer 6

Planting varieties of plants that are susceptible to disease

Over - crowding

Poor mineral nutrition

Damp warm conditions

Climate change

Question 7

How does overcrowding increase transmission of communicable diseases?

Answer 7

e.g. TB

• can remain in air for long time and infect new people
• spread by droplet infection

Plants

• increases chance of contact

Question 8

How does climate change increase transmission of communicable diseases?

Answer 8

e. g. late blight
- wet summers : spores need water to spread

e. g. malaria
- hot and humid : ideal conditions for mosquitoes to breed

Question 9

How do socioeconomic factors increase transmission of communicable diseases?

Answer 9

e. g. HIV
- limited access to good healthcare : people less likely to be diagnosed and treated, effective drugs less available
- limited access to good health education : less informed about how transmitted and avoided eg safe sex