1 - Introduction

Question 1

What are the impact of parasites on the host animal

Answer 1

Compete for nutrition
mechanical obstruction
Suck or consume bodily fluids
Pressure atropy
Allergic reactions
Produce toxic substances
carry pathogens including other parasites
Injury on entry and or migration

Question 2

How do parasites impact the host animal by competing for nutrition?

Answer 2

By ingesting intestinal contents - ascarids (roundworms)
By absorbing them thru body walls - tapeworms

Question 3

How do parasites impact the host animal by mechanical obstruction?

Answer 3

of the intestines - ascarids
Of the bile ducts - ascarids, trematodes
Of the blood vessels - canine heartworm
of the bronchi or trachea - lung worms
of the lymph channels - filarial nematodes

Question 4

How do parasites impact the host animal by sucking or consuming bodily bluids

Answer 4

Blood - mosquitoes, hookworm
Lymp - midges
Exudates - lungworms

Feed on or destroy solid tissues
Directly - giant kidney worms, liver flukes
After liquefying them - chiggers

Question 5

How do parasites impact the host animal by pressure atropy

Answer 5

Hydatid cysts (echinococcus spp)

Question 6

How do parasites impact the host animal by allergic reactions

Answer 6

Hypersensitivity, scar tissue (pig livers)
Black flies, mosquitoes, fleas

Question 7

How do parasites impact the host animal by produce toxic stubstances

Answer 7

Hemolysins, histolysins (break down tissues), anticoagulants

Question 8

How do parasites impact the host animal by carrying pathogens including other parasites

Answer 8

Mosquitoes - malaria, heartworm, WEE, WNV
Dog flukes - ‘salmon poisoning’

Question 9

How do parasites impact the host animal by injury on entry and/or migration

Answer 9

Creeping eruption - cutaneous larval migrans
Sarcoptic mange

reduce host’s resistance to other dz’s and parasites

Question 10

What is the vet techs job in parasitology?

Answer 10

dx and px, control and prevention, tx, public health, client ed
COMMUNICATION

Question 11

What is the functional definition of parasitism?

Answer 11

A parasite is a smaller organism(typically) that lives within or on top of another, generally lger, organism, the host
The parasite will cause some degree of harm to the host. this “harm” ranges from mild-severe
The parasite absolutely requires the host to complete its life-cycle

Question 12

What are the types of parasites?

Answer 12

Macroparasites - helminths, arthropod
Microparasites - protozoa, bact, fungi, viruses

Question 13

What different types of helminths?

Answer 13

Worms!
Nematodes - roundworms, hookworms, pinworms, whipworms, etc toxocara canis - dog roundworm
Flat worms - cestodes, diphyllobothrium spp (tapeworm of fish-eating vertebrates), trematodes (flukes), fascioloides manga (giant liver flukes of ruminants

Question 14

What are some examples of parasitic arthropods?

Answer 14

bugs, fleas, flies, lice, mites and ticks

Question 15

What do tapeworms =

Answer 15

cestodes

Question 16

What are different types of protozoa parasites?

Answer 16

amoeboids, ciliates, flagellates, sporozoans (apicomplexans (coccidia))

Question 17

In regards to hosts for parasites, what does definitive host mean?

Answer 17

DH = definitive host
Required for ALL parasites (need hot to survive or reproduce)
Adult parasites are in the DH. Parasite undergoes sexual reproduction inside DH
sometimes asex in the DH

Question 18

What is an intermediate host?

Answer 18

Required for MANY parasites (indirect life cycles)
Parasite undergoes development within IH
never sexual reproduction

Question 19

What is a paratenic host?

Answer 19

PH - helpful but not required
Infectin occurs but no reproduction
no development

Question 20

What is a transport host?

Answer 20

Helpful but not required
no infection. Simple transport (mechanical vector)

Question 21

WHat is the shedstage and the infective stage?

Answer 21

Shed stage is what leaves the infected host (egg, larva, cyst)
Infective stage is what is infective to the next host - usually takes time in the environment for a shed stage to become in infective stage
Pre patent period (PPP) (infected but not shedding detectable #’s)
patent (infected and shedding detectable #’s of shed stages)
Prevalence (% infected in a population) and intensity (how many parasites in an infected animal

Question 22

How does one aquire parasites?

Answer 22

ingestion of infective stages fron contaminated environment
Ingestion of infective stges in infected IH, often regular prey
Skin penetration
Inoculation of infective stages by infected arthropod vectors
transfer by direct contact w/ other infected hosts
trasnmammary infection of larvae from mother to offspring

Question 23

Give an example of an infected horse with adult worms in the intestine spreading directly

Answer 23

Eggs pass in the feces -> larvae hatch from eggs -> horse ingests larvae while grazing and becomes infected -> larvae mature to adult worms, which produce to make worms

Question 24

Give an example of an indirect parasite life cycle using a wolf

Answer 24

A wolf has a parasite-> shed thru feces-> parasite in grass->moose eats grass as IH-> ingests the egg and larvae migrate to target tissue -> wolf eats infected moose