Lecture 7: Ectoparasite/Vector

Question 1

Define ectoparasite

Answer 1

Ectoparasite: a parasite that lives in skin of hots for part or all of life cycle + takes something from host (usually with a negative impact)
* Mainly arthropods

Question 2

Define vector

Answer 2

Vector: organism that transmits pathogen/parasite between hosts (often from blood feeding)

Question 3

How to arthropods/vectors find a host

Answer 3

• Complex – behaviour in response to cues
  o Cues: visual/odor/heat/activity
  o Receptivity to cue depends on: repro stage/nutritional status/age/circadian rhythm/host specificity/pathogen load
• Active searching: biting – mosquito/horse fly
• Waiting/ambush: flea/lice
• Ticks can do both (questing)

Question 4

Why is understanding how arthropods/vectors find hosts important

Answer 4

• Method of host acquisition can inform control methods

Question 5

What are 3 methods arthropods/vectors use for blood feeding

Answer 5

1. Solenophagy: vessel feeding via capillary
2. Telmophagy: drink from pool of blood in wound

Question 6

Provide some examples of arthropods or vectors that use solenophagy

Answer 6

a. Mosquito/flea/lice/bed bugs

Question 7

Provide some examples of arthropods or vectors that use telmophagy

Answer 7

a. Ticks/sand flies/stable flies/horse flies

Question 8

How do arthropods/vectors protect themselves from pathogens when blood feeding

Answer 8

• Preventing pathogens infecting during bloodmeal:
  o Immune: similar to mammalian
  o Peritrophic matrix: lines midgut – like a sieve (prevent pathogens from entering GI lining)

Question 9

What is biological transmission of pathogens in arthropods/vectors?

Answer 9

Biological: vector exposed to pathogen from host
* Lifecycle of pathogen depends on the type
* Lifecycle of pathogen occurs in the vector (sexual repro) – vector usually definitive host

Question 10

What is extrinsic incubation period

Answer 10

• Extrinsic incubation period: time from bloodmeal ingestion to when vector can transmit

Question 11

What is mechanical transmission of pathogens in arthropods/vectors?

Answer 11

• Arthropod/vector carry pathogen but not infected
• Can carry in/on body
• Pathogens have low specificity for vector and transmit via physical contact

Question 12

What are some examples of mechanical transmission of pathogens in arthropods/vectors?

Answer 12

• Ex. myxoma virus (rabbits), tularemia