Lecture 6: Virulence and Pathogenicity of Parasites

Question 1

Three groups of eukaryotic organisms that afflict health and well-being

Answer 1

• Protozoa
• Helminths
• Arthropods

Question 2

Ectoparasite

Answer 2

• Lives on host

- Causes infestations

Question 3

Endoparasite

Answer 3

• Lives in host

- Causes infections

Question 4

Definitive host

Answer 4

harbors adult (sexual) stage of parasite

Question 5

Intermediate host

Answer 5

harbors larval stage (asexual) of the parasite

Question 6

Incidental host

Answer 6

an unusual host, unnecessary for the maintenance of the parasite in nature

Question 7

Parasites have specificity for particular definitive and intermediate hosts, meaning

Answer 7

often parasitic life cycles can only be completed in a particular host

Question 8

In different hosts, disease manifestations may

Answer 8

differ

Question 9

6 common routes of parasite entry

Answer 9

• Ingestion
• Skin/mucosal
• Transplacental
• Transmammary
• Anthropod bite
• Sexual contact

Question 10

Protozoa multiply where?

Answer 10

in hosts

Question 11

Do helminthes multiply in definitive host?

Answer 11

-Not in definitive host

Question 12

Severity of Helminth disease is proportional to

Answer 12

worm load introduced in the host

Question 13

Two methods of attachment

Answer 13

• Mechanical or biting mouthparts

- Molecular interaction

Question 14

Three types of mechanical tissue damage

Answer 14

• Blockage of internal organs
• Pressure atrophy
• Migration through tissue

Question 15

Three types of toxic parasite products

Answer 15

• Destructive enzymes
• Endotoxins
• Toxic secretions

Question 16

Three ways to lose nutrients

Answer 16

• Competition with hosts
• Interference with nutrient absorption
• Nutrient loss

Question 17

Natural or innate immunity

Answer 17

A defense mechanism that does not depend upon prior exposure to the invader

Question 18

Three types of natural or innate immunities

Answer 18

• Cytokines/cytokine receptors
• Antimicrobial molecules and pattern recognition receptors
• Cellular defense/phagocytosis

Question 19

Acquired immunity

Answer 19

Conferred by a host’s specific immunity response developed as a result of previous parasitic infection

Question 20

Two types of acquired immunity

Answer 20

• Premunition

- Concomitant immunity

Question 21

Premunition

Answer 21

Resistance to superinfection by presence of parasites in check by host immunity-malaria, toxoplasmosis

Question 22

Concomitant immunity

Answer 22

a parasite elicits a protection against reinfection, but the parasite itself remains in the host, unaffected by the immune response