Lecture 34: Disease-Pathogen Host Interactions

Question 1

Disease

Answer 1

Abnormal condition that impairs bodily function associated with certain symptoms and signs

(Not limited to pathogens)

Question 2

Pathogen

Answer 2

Disease-causing organism

Question 3

Host

Answer 3

An organism that harbors another

Question 4

Vector

Answer 4

An organism that transmits a pathogen from a reservoir to a host (different species from vector)

Question 6

Describe the two mechanisms of Parasite Transmission

Answer 6

Vertical: Parent to offspring (often sexually transmitted)

Horizontal: Parasite moves host to host (other than parent to offspring)

Question 7

Endoparasite

Answer 7

Lives inside of host’s body rather than outside

Question 8

Does parasite movement always require a vector?

Answer 8

No! Can be airborne, waterborne, etc. But can require a vector (ex. malaria).

Question 9

Mechanical transfer of pathogens

Answer 9

Pathogen does not replicate inside the vector (picks up a pathogen and moves it somewhere else)

Question 10

Biological transfer of pathogens

Answer 10

Pathogens replicate within the vector (propagative, cyclodevelopmental, cyclopropagative)

Question 11

Single-cycle pathogen

Answer 11

Only one species of host.
Type of biological transfer.

Question 12

Why is it difficult to eradicate malaria even though it’s a single-cycle disease?

Answer 12

No effective cures
No large-scale, environmentally-safe means to control vectors
Insecticides, pyrethroids, DDT (but mosquitos becoming immune)
Genetically modified mosquitos - CRISPR used to sterilize males and control populations
Etc.

Question 13

DDT was a highly effective and widely used insecticide. What did this lead to?

Answer 13

Intense selection pressures lead to insecticide resistance.

Question 14

Zoonotic (secondary) cycle pathogen transfer

Answer 14

2+ host species (animal hosts = “reservoir” hosts).
Type of biological transfer.

Question 15

What does elimination of a zoonotic pathogen require?

Answer 15

Must be eliminated in both humans and animal reservoirs hosts and vectors.

Question 16

Urban cycle

Answer 16

Pathogen transfer between humans and urban vectors or urban animals and their vectors

Question 17

Sylvatic cycle

Answer 17

Pathogen transfer between wild animals and vectors