Lecture 1

Question 1

Parasitism

Answer 1

A type of symbiotic association between two species where one benefits (the parasite) by exploiting the resources of the other (the host)

Question 2

____ ____ (the parasite) must be ____ between hosts, and the harm inflicted manifests as an illness or “disease”.

Answer 2

Infectious agent; transmissible

Question 3

Endoparasites

Answer 3

Parasites that complete some or all of their life cycle within host tissues or cells

Question 4

Two types of endoparasites

Answer 4

Microparasites and macroparasites

Question 5

Microparasites (or pathogens)

Answer 5

Microscopic parasites characterized by high rates of reproduction directly within their hosts, usually inside host cells

Question 6

Viruses

Answer 6

Composition: RNA/DNA encapsulated within a protein coat
Size: ~20 — 300nm (need electron microscope to observe)
Reproduction: “hijack” host cellular machinery, cannot reproduce independently (which is why they are not categorized as living things)
Reproduction speed: Extremely rapid
Examples: West Nile virus, Ebola, SARS, Measles

Question 7

Bacteria

Answer 7

Classification: Prokaryotes (living organism)
Size: ~1–5um (can be viewed with a light microscope)
Several forms available:
- Rods (bacilli)
- Spheres (cocci)
- Spiral (spirochetes)
Examples: Lyme disease, Anthrax, Typhoid fever, Cholera, Salmonella

Question 8

Protozoa

Answer 8

Classification: Unicellular eukaryotes (“animal-like” protists)
Size: 5–15um (can be viewed with a light microscope)
Examples: Malaria, Giardia, Leishmaniasis

Question 9

Macroparasites

Answer 9

Parasites that are visible with naked eye and has longer generation times (primarily “helminths” — parasitic worms)

Question 10

Major and minor taxa of Microparasites

Answer 10

*3 Major taxa:
- Viruses
- Bacteria
- Protozoa

Minor ones:
- Fungi
- Prions

Question 11

Major taxa of macroparasites

Answer 11

• Nematodes (roundworms)
  Ex. River blindness
• Trematodes (flatworms)
  Ex. Schistosomiasis
• Cestodes (tapeworms)
  Ex. Echinococcus

Question 12

Ectoparasites

Answer 12

Parasites that live on the surface of their hosts
Ex. Ticks, mites, fleas, mosquitoes, leeches

Question 13

Direct disease transmission

Answer 13

Physical or close contact between hosts allow disease agent to transfer from an infected host to an uninfected one.

Question 14

Indirect disease transmission

Answer 14

Transfer of a disease agent from an infected host to an uninfected one facilitated by an intermediate host or a vector.

Question 15

The 3 ecological origin of infectious diseases

Answer 15

• Zoonotic: Only transmit from animals to humans
• Multi-host: Transmit between both animals and humans
• Human-specific: Transmit human-to-human

Question 16

How and where does macroparasites develop through life?

Answer 16

Macroparasites complete only part of their life cycles within their hosts and then release infective stages from the host.