Micro Unit 2: Parasites

Question 1

mutualism

Answer 1

both members of association benefit

ex. E. coli in human GI tract

Question 2

symbiosis

Answer 2

“life together”, 2 organisms live in an association with one another. 3 types: mutualism, commensalism, parasitism

Question 3

commensalism

Answer 3

no benefit or harm to either member

ex. Staphylococcus epidermis on human skin

Question 4

parasitism

Answer 4

an organism that grows, feeds, and is sheltered on or in a different organism while contributing nothing to the survival of its host. implies that parasite can damage host.

Question 5

most common parasitic infections in US

Answer 5

trichomoniasis, giardiasis, cryptosporidiosis, toxoplasmosis

Question 6

life cycle of parasites

Answer 6

immature and mature phases

IMMATURE: parasite partially develops inside another species, called the intermediate host. This is where the asexual life cycle occurs in Plasmodium.

MATURE: harbors sexually mature parasites in the definitive host (the mosquito in plasmodium)

Question 7

parasitic protozoa

Answer 7

unicellular

amoeba, flagellates, ciliates, sporozoa

Question 8

parasitic helminths

Answer 8

multicellular

nematodes (roundworms), cestodes (flatworms/tapeworms), treamatodes (flukes)

Question 9

5 ways that host animal can be infected by parasite

Answer 9

1. direct ingestion of infective larvae, cysts, or eggs
2. eating the intermediate host
3. parasite actively penetrates principal host
4. maternally transmitted
5. vector borne transmission (Lyme, malaria)

Question 10

parasitic infection symptoms

Answer 10

• can be GI, blood borne, tissue infection
• typically chronic
• often asymptomatic, or symptomatic for a period of time and symptoms disappear only to come back later on
• parasite can remain dormant in host
• can have life-threatening consequences

Question 11

immune response to parasitic infection

Answer 11

Both innate and adaptive

INNATE: phagocytosis of parasite, release of cytokines, activation of complement system

ADAPTIVE: antibody formation. specific antibody can damage protozoa, neutralize parasites by blocking attachment to host cell, prevent spread of parasite, promote complement lysis, enhance phagocytosis and destruction thru antibody-dependent cellular toxicity

Question 12

what are parasitic infections characterized by?

Answer 12

eosinophilia and high levels of IgE (binds to mast cells and basophils)

Question 13

parasite survival strategies

Answer 13

antigenic mimicry, antigenic shedding, antigenic variation, antigenic concealment

Question 14

antigenic mimicry

Answer 14

incorporation of host “self” antigens into parasite surface

Question 15

antigenic shedding

Answer 15

shedding of surface antigens or components

Question 16

antigenic variation

Answer 16

gene switching, random mutations

Question 17

antigenic concealment

Answer 17

intracellular survival within macrophage