Module 5 - Parasitology

Question 1

Parasitism

Answer 1

Symbiotic relationship in which one animal, the host, is to some degree injured through the activites of the other animal, the parasite

Question 2

Obligate parasites

Answer 2

parasites that cannot survive outside of the host

Question 3

Faculative parasites

Answer 3

parasites that may exist in a free-living state or within a host

Question 4

Populations predisposed to getting parasites

Answer 4

• individuals in underdeveloped areas and countries
• Refugees
• Immigrants who are immunocompromised
• Individuals living in close quarters
• Children who attend day care centers

Question 5

Modes of transmission of parasites

Answer 5

• Ingestion of contaminated food or drink (primarily water)
• Hand to mouth transfer
• Entry via drilling through the skin
• unprotected sexual relations
• Transplacental
• Eye contact with infected swimming water

Question 6

Classification of Human parasites

Answer 6

Endoparasites and Ectoparasites

Question 7

Protozoans

Answer 7

type of endoparasites

amebae, flagellates, ciliates, sporozoa, coccidia, and microsporidians

Question 8

Helminths

Answer 8

Type of endoparasites

Platyhelminthes and Nematoda

Question 9

Platyhelminthes

Answer 9

type of endoparasite and helminth
cestodes, and trematodes
(flatworms)

Question 10

Nematoda

Answer 10

Type of endoparasite and helminth

roundworms

Question 11

Arthropod

Answer 11

type of ectoparasite

insects, spiders, mites, ticks

Question 12

Roundworm

Answer 12

(Heliminth-Nematoda)

• free-living
• mouth = 3 lips or buccal capsule and cutting plates
• sexes - larger female
• interintestinal and extraintestinal (tissue/blood)

Question 13

Tapeworm

Answer 13

(Cestode - Platyheminthes - Helminths)

• scolex with suckers for attachment
• proglottids for body segments
• Hermaphroditic
• intermediate host needed for larval stage

Question 14

Scolex

Answer 14

Anatomy used for attachment

• found at anterior end
• can have suckers or hooks

Question 15

Proglottids

Answer 15

segments of the body

Question 16

Definitive Host

Answer 16

harbors the adult or sexual stage of the parasite or the sexual phase of the life cycle

Question 17

Intermediate Host

Answer 17

habors the larval or asexual stage of the parasite or the asexual phase of the life cycle

Question 18

Accidental host

Answer 18

can serve as a host but is not a usual host in that parasite’s life cycle

Question 19

Fluke

Answer 19

(trematode - Platyheminthes - Helminths)

• Leaf-shaped or elongated, slender bodies
• Possess hook or suckers for attachment
• Found in the intestinal tract, liver, blood vessels, and lungs
• Most are hermaphroditic
• Complex life cycles that require one or two intermediate hosts

Question 20

Amebae

Answer 20

(protozoan)
trophozoite and cyst stages
- When cysts are swallowed and pass to the lower intestine, they excyst and begin to multiply as feeding trophozoites

Question 21

Trophozoite

Answer 21

The motile feeding stage that reproduces by binary fission

- causes symptoms

Question 22

Cyst

Answer 22

An infective, environmentally resistant stage

- similar to spores

Question 23

Specimens for parasite ID

Answer 23

Stool, blood, tissue and other body fluids (CSF, skin snips, liver biopsy, sputum)

Question 24

Laboratory Methods for diagnosing parasitic disease

Answer 24

Macroscopic (gross exam), Microscopic (direct wet mounts, concentrated, permanently stained), cellophane tape, Immunoassays, direct flurescent antibody

Question 25

Direct smear

Answer 25

type of diagnostic technique for helminths

Question 26

Trichrome stain

Answer 26

type of diagnostic technique for protozoans

Question 27

Modified Kinyoun acid-fast stain

Answer 27

type of diagnostic technique for cryptosporidium

Question 28

How does intermittent shedding impact Laboratory tests

Answer 28

Shedding in waves means that if specimen is collected only once from a person a possiblity is left for the parasite to get missed (not shedding at the moment)
- mutiple stools should be collected over the course of 10 days

Question 29

why must liquid stools be examined within 30 minutes of passage?

Answer 29

Motile trophs do not last long outside of a host

- bodies can breakdown and cause a false negative result

Question 30

Difficulties involved with using antiparasitic Agents

Answer 30

• eukaryotic organisms
• chronic infection
• complex life cycles/ differential stages
• developing countries - high immunocompromised pop, high poverty, poor sanitation

Question 31

Targets for antiparasitic agents

Answer 31

• energy metabolism
• cell wall synthesis
• protein synthesis
• membrane function
• Nucleic acid synthesis
• cofactor synthesis

Question 32

Compare antihelminth agents to antiprotozoan

Answer 32

Antihelminth agents target nonproliferating adult organisms, whereas the antiprotozoan agents target younger, more rapidly proliferating cells

Question 33

Praziquantel - mechanism of action

Answer 33

serves as a calcium antagonist and causes tetanic muscular contractions; drug causes disruption of the parasitic surface and tegument, allowing antibodies to attack parasitic antigens not normally exposed on the surface (synergistic with host immune system)

Question 34

Treatment options other than drugs for parasites

Answer 34

Change in diet, Vitamin supplements, Fluid replacement, Blood transfusion, Bed rest