Chapter 19: Epidemiology - Transmission of disease

Question 1

What are the three principle routes of transmission?

Answer 1

1. Contact transmission
2. vehicle transmission
3. Vector transmission

Question 2

What are the 3 types of contact transmission?

Answer 2

1. direct
2. Indirect
3. Droplet

Question 3

What is direct contact transmission?

Answer 3

• person to person contact
  ex. Chlamydia, other STDs

Question 4

What is indirect contact transmission?

Answer 4

• through fomites

Question 5

What is droplet contact transmission?

Answer 5

• spread a short distance (<1m)
  ex. coughing, sneezing, talking
  ie. influenza

Question 6

What is vehicle transmission?

Answer 6

• pathogens transmitted by a medium

Question 7

What is waterborne vehicle transmission?

Answer 7

• due to improperly treated sewage
  ex. E. coli

Question 8

What is airborne vehicle transmission?

Answer 8

• spread > 1m in droplets
  ex. Mycobacterium tuberculosis

Question 9

What is foodborne vehicle transmission?

Answer 9

• food poisoning
  ex. salmonellosis

Question 10

What is vector transmission? (2)

Answer 10

• animals that carry pathogens from one host to another
• usually insects

Question 11

explain the pathway of West Nile virus in terms of vector transmission

Answer 11

Birds (reservoir) –> mosquitoes –> humans

Question 12

explain the pathway of Lyme disease in terms of vector transmission

Answer 12

field mice (reservoir) –> ticks –> humans