Parasitology Lecture 8

Question 1

Definition of parasite

Answer 1

an organism that lives on or in a host organism and gets its food from or at the expense of its host

Question 2

True or false: viruses, bacteria, and fungi can be considered parasites

Answer 2

True (although it depends on who you’re talking to)

Question 3

Medical parasites are considered as ____ ____

Answer 3

eukaryotic pathogens

Question 4

How many species of protozoans are known to be human parasites?

Answer 4

70

Question 5

How many species of helminths are known to be human parasites?

Answer 5

300

Question 6

True or false: there are thousands of parasites known to exist, but only a small subset affect humans

Answer 6

True

Question 7

The number of parasites is growing due to:

Answer 7

sequencing

Question 8

True or false: some parasites are insects or arachnid ectoparasites

Answer 8

True

Question 9

Since we’re considering eukaryotic parasites, some key features they have are: (2)

Answer 9

membrane-bound organelles, nucleus

Question 10

True or false: there isn’t much diversity regarding the parasites that infect livestock

Answer 10

False - huge diversity (there are some overlaps)

Question 11

True or false: some parasites infect plants

Answer 11

True

Question 12

What are 3 classes of human parasites?

Answer 12

1. Protozoa
2. Helminths
3. Ectoparasites

Question 13

Depending on life cycle, protozoa may be __-___ or ____

Answer 13

free-living or parasitic

Question 14

True or false: pathogenic protozoa don’t usually multiply in humans, whereas worms can multiply in humans

Answer 14

False - worms usually don’t multiply in humans but protozoa do

Question 15

Common modes of transmission of protozoa include: (2)

Answer 15

1. fecal-oral route (GI inhabitant)

2. arthropod vector (blood/tissue inhabitant)

Question 16

Name the 4 categories of pathogenic protozoa based on mode of movement

Answer 16

1. Amoebozoa (pseudopods)
2. Mastigophora (flagellates)
3. Ciliophora (ciliates)
4. Sporozoa (not motile in adult stage)

Question 17

Example of Amoebozoa

Answer 17

Entamoeba

Question 18

Example of Mastigophora

Answer 18

Giardia, Leishmania

Question 19

Example of Ciliophora

Answer 19

Balantidium

Question 20

Example of Sporozoa

Answer 20

Plasmodium

Question 21

Which of the following classes of Protozoa reproduces via schizogony?
A. Amebas
B. Ciliates
C. Sporozoa
D. Flagellates

Answer 21

C. Sporozoa

Question 22

Binary fission

Answer 22

Cell contents double and are halved into 2 daughter cells

Question 23

Schizogony

Answer 23

Huge amplification process within a host cell to increase progeny, after a certain amount of time the nuclei acid material splits up and is released

Question 24

Entamoeba histolytica lives in the ___ and causes:

Answer 24

gut; dissolves tissue

Question 25

True or false: Plasmodium falciparum is the most deadly of the malaria parasites

Answer 25

True

Question 26

Trypanosoma cruzi appearance in blood smear:

Answer 26

stain purple, extracellular (not found inside RBC), large kinetoplast, centrally located nucleus

Question 27

Leishmania donovani is usually found within ___ ____

Answer 27

bone marrow

Question 28

Helminth parasites are ___, ___-____ organisms

Answer 28

large, multi-cellular

Question 29

True or false: helminths are usually visible to the naked eye as adults

Answer 29

True

Question 30

True or false: helminths can be free-living or parasitic

Answer 30

True

Question 31

Three main groups of helminths:

Answer 31

1. flatworms (trematodes) 2. Cestodes (tapeworms) 3. Roundworms (nematodes)

Question 32

True or false: thorny-headed worms are common parasites that infect humans

Answer 32

False - rare

Question 33

3 characteristics used to categorize helminths

Answer 33

morphology, sex, GI tract

Question 34

Roundworm morphology

Answer 34

Earthworm shaped (or spindle)

Question 35

True or false: Roundworms are hermaphroditic

Answer 35

False - separate sexes

Question 36

Roundworm GI tract

Answer 36

tubular

Question 37

Tapeworm morphology

Answer 37

head with segmented body

Question 38

Tapeworm GI tract

Answer 38

none - each segment absorbs nutrients/excretes waste

Question 39

Fluke morphology

Answer 39

leaf shape with oral/ventral suckers (to attach to lumen)

Question 40

Both tapeworms and flukes are ______

Answer 40

hermaphroditic

Question 41

Schistosoma parasites cause disease in:

Answer 41

GI tract and bladder

Question 42

Ectoparasites are:

Answer 42

ticks, fleas, lice, and mites that attach or burrow into the skin and remain there for relatively long periods of time

Question 43

Ectoparasites effects on host (2)

Answer 43

1. directly cause disease | 2. transmit pathogens (most)

Question 44

True or false: blood-sucking arthropods like mosquitoes may be considered as ectoparasites

Answer 44

True

Question 45

Examples of important intestinal parasites in the US

Answer 45

Enterobius vermicularis, Giardia lamblia, Entamoeba histolytica

Question 46

Historically, what types of people are at the highest risk for parasitic infection?

Answer 46

Minorities, immigrants, and poor/disadvantaged people (those w/o access to healthcare)

Question 47

Why is it important to know the geography and host range of parasites?

Answer 47

Often can be a defining factor or help us diagnose if we know where Pt has been or where they are

Question 48

Definitive host

Answer 48

organism where sexual cycle of parasite occurs

Question 49

Intermediate host

Answer 49

organism that harbors parasite for transition period, often where asexual cycle occurs

Question 50

Accidental host

Answer 50

Non-natural host but may cause infection if there's contact

Question 51

Dead end host

Answer 51

intermediate host that can't transmit the infection to the definitive host

Question 52

Delusional parasitosis

Answer 52

rare psychiatric disorder in which Pt has a fixed, false belief that they're infested with parasites (often reject psychiatric intervention but treated with antipsychotic meds/counseling)

Question 53

Examples of structures that can be mistaken for parasitic material

Answer 53

Plant material, pollen, vegetable cells, weird looking platelets, Charcot-Leyden crystals, nucleated RBC, Howell-Jolly bodies