Lecture 46 - Intro to Protozoa

Question 1

T/F: all protozoa are free-living

Answer 1

FALSE - some are parasitic

Question 2

how do protozoa reproduce

Answer 2

1. binary fission
2. budding
3. multiple fission
4. sexual

Question 3

symbionts

Answer 3

2 organisms that live in close association with each other

Question 3

parasitic protozoa life-cycle

Answer 3

infection of hosts and reproduction

Question 4

parasite

Answer 4

a symbiont that is dependent on host organisms

Question 5

parasitic protozoa pathology

Answer 5

mechanisms that cause disease in the host

Question 6

direct life cycle

Answer 6

requires single host species

Question 7

indirect life cycle

Answer 7

requires an intermediate host species

Question 8

facultative indirect life cycle

Answer 8

can use an intermediate host but not required

Question 9

transmission to new hosts

Answer 9

route, infectious immediately or need to develop

Question 10

stages of protozoa

Answer 10

1. cysts (resistant)
2. trophozoite (growing)
3. tachyzoite (fast-growing)

Question 11

T/F: high host specificity is important for zoonosis

Answer 11

FALSE - low host specificity

Question 12

definitive host

Answer 12

supports protozoa asexual and sexual reproduction

Question 13

intermediate host

Answer 13

supports asexual multiplication
indirect - through the food chain
REQUIRED

Question 14

facultative intermediate (paratenic) hosts

Answer 14

supports asexual multiplication
indirect - through the food chain
NOT required to complete a life cycle

Question 15

accidental/aberrant/dead-end host

Answer 15

supports asexual multiplication
won’t complete its lifecycle

Question 16

giardia

direct or indirect?
immediately infectious?
stages?

Answer 16

direct
yes - immediately infectious
cysts and trophozoite

Question 17

toxoplasma

direct or indirect?
immediately infectious?
different hosts?

Answer 17

both direct and indirect
no - not immediately infectious
definitive (cat)
facultative intermediate (opossum)
accidental host (human)

Question 18

what are 4 reasons we need to know life cycles

Answer 18

1. control disease
2. diagnose
3. educate
4. treatment

Question 19

what are the 4 main mechanisms of protozoa pathogenesis

Answer 19

1. direct
2. indirect
3. immunomodulation
4. excretion of toxins

Question 20

describe direct pathogenesis

Answer 20

asexual reproduction inside the host cells causing cellular and organ trauma

Question 21

describe indirect pathogenesis

Answer 21

proliferation on the host cell surface
impairment, damage or apoptosis

Question 22

describe immunomodulation pathogenesis

Answer 22

1. autoimmune reactions (generate autoantibodies against self)
2. suppression (alters immune response for longevity)

Question 23

describe the excretion of toxin pathogenesis

Answer 23

secrete toxic substances
cause inflammation and host cell apoptosis

Question 24

what is the best way to describe an indirect life-cycle

Answer 24

when a parasite’s life cycle must include an intermediate host species