Disease Transmission

Question 1

Disease Triad

Answer 1

Question 2

Define: Infectious Disease, Infestation, Contagious, Communicable, Zoonotic disease

Answer 2

Infectious Disease- caused by invasion of a living agent in/on host

Infestation- invasion but not multiplication of organism in/on host

Contagious- transmissible via direct or airborne routes

Communicable- caused by agent by direct or indirect routes

Zoonotic disease-transmitted animal to humans

Question 3

Flow chart of infectious disease

Answer 3

Question 4

“chain of infection”

Answer 4

“chain of infection”

Question 5

Resevoirs

Answer 5

Resevoir= habitat in which infectious agent lives/grows

Resevoirs MAINTAIN pathogens over time

Requirements for animal as resevoir:

• is it infected naturally with pathogen
• can species mainain pathogen over time
• can it transmit disease to new host

Question 6

Direct Transmission

Answer 6

Direct Transmission

• Vertical: from a reservoir host to its offspring
  
  • congenital
  • perinatal
• Horozontal: from the reservoir to a new host
  
  • direct contact
  • direct projection (sneeze)
  • airborne (air)

Question 7

Vehicles vs. vectors

Answer 7

Vehicles: inanimate object which transferes disease

• common vehicle-food or water
• fomites- contaminated object (ex. doornob)

Vectors: living organism that transfers disease

• mechanical- agent doesnt multiply in host
• biological- angnt changes in host and these activities are required for transmission

***horozontal disease transmission

Question 8

Emerging vs. re-emerging Disease

Answer 8

Emerging disease

• previously unknown disease that emerges
• know disease that appears in a new population

Re-emerging disease

• known disease, becoming more common, and projected to continue progression

Question 9

5 Stages of Cross-Species Disease Emergence

Answer 9

Question 10

Determinanats of disease emergence

Answer 10

Determinanats of disease emergence

Pathogen

• type of agent
  
  • most are zoonotic disease
• pathogen adaptation
  
  • antibiotics resistance
  • mutations

Resevoirs

• best transmission between same species
• more likely spread between closely related species

Transmission

• resevoir size
• pathogen prevalence
• contact frequency

Host

• succeptibility

Question 11

4 Portals of Entry for Transboundary Disease

Answer 11

4 Portals of Entry for Transboundary Disease

• animals/animal products
• vectors
• fomites
• people

Question 12

Flow chart disease transmission

Answer 12