Internal Parasitology II

Question 1

Acanthocephala

Answer 1

thorny headed worm
DH: fish, birds, mammals, amphibians, reptiles
IH: arthropods
TO: intestine
transmission: ingestion of IH or paratenic host
spiny proboscis attaches to intestine lining and creates ulcers and perforations

Question 2

cestodes

Answer 2

aka tapeworm
segmented flatworm
small and oval shaped
some have thick walls
sometimes mistaken for coccidia
hooks are visible

Question 3

Taenia spp.

Answer 3

cestode
DH: cats and dogs
IH: rabbits and rodents
TO: small intestine

Question 4

larval stage

Answer 4

cysticercus

Question 5

Echinococcus

Answer 5

cestode
DH: carnivores and omnivores
IH: herbivores
infections in US are rare
zoonotic: significant disease/death in humans
larval stage= hydatid cyst

Question 6

Dipylidium caninum

Answer 6

cestode
DH: dogs and cats
IH: fleas
eggs found in packets within proglottid
gravid proglottids crawl out of anus
flea larva eat eggs
cysticercus develop within flea
DH is infected by ingesting adult flea

Question 7

proglottid

Answer 7

one segment of a tapeworm that contains female and male reproductive organs

Question 8

what are the 3 parasitic stages of Dipylidium caninum

Answer 8

1. ova/proglottids in feces
2. cysticercus in flea
3. adult in DH

Question 9

Anoplocephala spp

Answer 9

cestode
DH: equids
IH: pasture mite
similar life cycle to other tapeworms
round or D-shaped

Question 10

Monezia spp

Answer 10

cestode
DH: ruminants worldwide
IH: mite

Question 11

trematodes

Answer 11

aka flukes
unsegmented flatworms
anterior and ventral suckers for attachment in host
DH: dogs, cats, ruminants
IH: usually more than one
snails usually 1st
frogs or fish 2nd
some are zoonotic
ID: large, oval, operculated ova
zoonotic: causes schistosomiasis in humans (swimmer’s itch)

Question 12

paragonimus kellicotti life cycle

Answer 12

trematode
1. infected feces mixes with body of water and eggs hatch in a ciliated form (miracidium)
2. penetrates 1st IH and develops into sporocyst
3. forms a cercaria through sexual reproduction
4. infects 2nd IH and develops into encysted metacercaria
5. final host (DH) ingests 2nd IH and becomes infected
TO: lungs

Question 13

fasciola hepatica

Answer 13

trematodes
DH: ruminants
IH: snail
transmission: ingestion
TO: liver
zoonotic
sheep are especially susceptible and die from it

Question 14

protozoa

Answer 14

single celled with 1 or more nuclei
direct fecal to look for giardia
locomotion: flagella, cilia, pseudopodia, undulatory ridges
ID: small, view with 10x or 40x

Question 15

coccidian types

Answer 15

isospora, eimeria, toxoplasma, cryptosporidia, sarcocystis

Question 16

flagelles

Answer 16

giardia and trichomonas

Question 17

what are the different protozoans?

Answer 17

coccidians, flagelles, ciliates, amoebas

Question 18

coccidian parasites

Answer 18

TO: colon, small intestine
oocyte shed in feces
sporulate in environment

Question 19

what conditions would cause a coccidian parasite to sporulate in the environment?

Answer 19

heat, moisture, oxygen
if the parasite is in the infective stage
number of sporozoites depends on species

Question 20

isospora

Answer 20

coccidia
DH: dogs, cats, birds, reptiles
each oocyte contains 2 sporocyst

Question 21

eimeria

Answer 21

coccidia
DH: horses, ruminants, swine, rabbits, rodents, birds, reptiles
4 sporocysts in each oocyte

Question 22

toxoplasma gondii

Answer 22

coccidian
DH: felids (feline family)
IH: all warm-blooded animals
transmission: ingestion of infective oocytes
zoonotic (most at risk: immunocompromised, pregnant women)

Question 23

toxoplasmosis

Answer 23

caused by toxoplasma gondii
more likely in cats with suppressed immune systems
CS: fever, loss of appetite, lethargy, pneumonia, CNS signs

Question 24

what parasite causes toxoplasmosis?

Answer 24

toxoplasma gondii

Question 25

cryptosporidia spp

Answer 25

coccidia
DH: mammals, reptiles
TO: stomach, small intestine
acid fast stain positive
transmission: ingestion of infective oocyst
zoonotic

Question 26

sarcocystis spp

Answer 26

coccidia
DH: predator
IH: prey
TO: muscle
generally nonpathogenic in DH
causes equine protozoal myeloencephalitis (EPM)

Question 27

equine protozoal myeloencephalitis (EPM)

Answer 27

DH: opossums
IH: infected prey
horse CS: ataxia, knuckling, muscle atrophy, neurologic signs (brain stem involved)

Question 28

giardia

Answer 28

flagellate
2 stages:
1. cyst: hardy and resilient, dormant stage
2. trophozoite: delicate, active/reproductive stage
floatation solutions destroy trophozoites
test through fecal float, direct/cytology, or antigen test
fecal float: cysts seen, use zinc sulfate solution
direct/cytology: trophozoites seen, fresh is best
antigen: tests for specific proteins created during cyst formation

Question 29

trichomonad types

Answer 29

trichomonas foetus, trichomonas gallinae, bovinetrichoumoniasis “trich”

Question 30

trichomonas foetus

Answer 30

flagelle
trichomonad
DH: cattle
TO: urogenital tract (sexual transmission)
causes spontaneous abortion
or
DH: cats
TO: large intestine (fecal-oral transmission)
causes chronic diarrhea

Question 31

trichomonas gallinae

Answer 31

trichomonad
DH: birds
TO: upper GI tract (fecal-oral)
causes plaque in mouth and can cause severe disease

Question 32

ciliates

Answer 32

protozoans

Question 33

balantidium spp

Answer 33

ciliate
DH: swine, reptiles, humans, NHPs
commensal but can be a opportunistic pathogen
B. coli zoonotic

Question 34

what stages can amoebas be in?

Answer 34

cyst and trophozoite stages

Question 35

entamoeba histolytica

Answer 35

amoeba
DH: humans, primates, dogs, cats
fecal-oral
pathogenic in humans and NHPs
dysentery= disease of intestines causing diarrhea with blood or mucus

Question 36

entamoeba invadens

Answer 36

amoeba
DH: reptiles (commensal in herbivores, pathogenic in carnivorous reptiles)
CS: anorexia, weight loss