Protozoa

Question 1

Characteristics of Protozoa

Answer 1

• 60,000 named/10,000 parasitic
• Eukaryotic, single-celled (unicellular)
• Organelles of locomotion (flagella, cilia, pseudopods)
• Protozoan reproduction (binary fission, multiple fission/schizogony, budding, conjugation, gametogony)
• protozoan nutrition (heterotrophic/autotrophic)
• found in diverse habitats

Question 2

Protozoan classification

Answer 2

Kingdom: Protista
Phylum: Sarcomastigophora/Apicomplexa/Ciliophora*/Microspora

Question 3

Protozoan reproduction

Answer 3

Asexual and Sexual
Binary fission- longitudinal/transverse, asexual
Multiple fission/schizogony
Budding
Conjugation
Syngamy-sexual

Question 4

Protozoan nutrition

Answer 4

Autotrophic- produces own nutrients by photosynthesis or chemosynthesis
Heterotrophic- obtain preformed nutrients from exogenous sources: holozoic- ingest particulate material through mouth/saprozoic- obtain nutrients absorb them through the cell membrane

Question 5

Giardia spp.

Answer 5

Hosts: humans, dogs, cats, calves, goats, sheep, horses, rabbits, rodents
Habitat: worldwide
2 forms- trophozoite/feeding stage; resistant cyst stage
transmitted via cyst stage, very hardy
Life cycle: direct; excyst in host duodenum, divide in host by longitudinal binary fission (asexual), encyst in lower intestinal tract
Trophozoites- diarrhea
Cysts- formed feces
Clinical signs: majority asymptomatic, diarrhea, weight loss, dry skin
Diagnosis: float- cysts; direct- tropozoites, ELISA

Question 6

Trophozoite

Answer 6

motile
four pairs of flagella
seen moving through direct fecal smear

Question 7

Resistant cyst stage

Answer 7

oval, thick refractile wall

occupy one end of the cyst

Question 8

Tritrichomonas spp.

Answer 8

flagellates; adapted to live in anaerobic environment, most don’t cause disease

Question 9

Characteristics of Trichomonads

Answer 9

pyriform with rounded anterior end/ pointed posterior end
Single nucleus in anterior portion of cell body
3-5 anterior flagella, posterior flagellum
undulating membrane
divide by longitudinal binary fission (asexual)
may form pseudocyst

Question 10

Pelta

Answer 10

sheet of microtubules that function as support for anterior flagella

Question 11

Axostyle

Answer 11

consists of simple or multilayered ribbons of microtubules that function as an internal cytoskeleton

Question 12

Parabasal body

Answer 12

trichomonad Golgi apparatus

Question 13

Blepharoplast or Basal body

Answer 13

centrosome-like structure from which the flagellum arises

Question 14

Costa

Answer 14

support for undulating membrane

Question 15

Hydrogenosome

Answer 15

spherical structure, commonly found along the axostyle and costa; functions as calcium store and producer of ATP and H+

Question 16

Bovine Genital Trichomoniasis

Answer 16

caused by Tritrichomonas foetus
distribution worldwide
transmitted by coitus
bulls- asymptomatic/females- vaginitis, pyometra
diagnosis- PCR, direct smear
control- use AI, replace old bulls, test new bulls

Question 17

Feline Trichomoniasis

Answer 17

large bowel disease- chronic diarrhea, tenesmus, flatulence, irritated anus, fecal incontinence
transmission unknown
age of onset- 9 mo, may relapse
diagnosis- direct fecal smear, culture, PCR, colonic biopsy
control- no litterbox sharing, keep away from infected cats

Question 18

Trypanosoma cruzi

Answer 18

found in blood, tissue, some intracellular
transmitted by blood feeding invertebrates
Zoonotic- Chagas disease, vector Reduviid bug
Amastigote- muscle/tissue; Trypomastigote- circulating blood
Life cycle: Reduviid bug feeds on host and deposits fecal matter containing Metacyclic trypomastigote, transform into amastigote stage (liver, spleen), binary fission occurs (asexual) form pseudocysts, cells rupture and trypomastigotes remain in circulation, transform into epimastigotes, replicate via binary fission
Chronic stage (dog)- lethargy, arrythmia, anemia, hepatomegaly
Diagnosis- ELISA, IFA, IHA, TESA blot, blood smear (acute)

Question 19

Characteristics of Trypanosomes

Answer 19

kinetoplast
pleomorphic
cytoskeleton
single nucleus
elongated cell body- single flagellum; rounded cell body- short flagellum

Question 20

Apicomplexa

Answer 20

distinct nucleus, subpellicular tubules
apical complex
orders: Eucoccidiida, Piroplasmida

Question 21

Cystoisospora (Isospora)

Answer 21

Stenoxenous/Monoxenous
Worldwide distribution
Organ specificity (small/large intestine)
Asexual and Sexual reproduction: sporogony, shizogony, gametogony
Sporulated oocyst- 2 sporocysts/4 sporozoites
dogs and cats, pigs, humans (severe in AIDS patients)

Question 22

Eimeria spp.

Answer 22

Stenoxenous/Monoxenous
Worldwide
Organ specificity
Asexual and Sexual reproduction
Sporulated oocysts- 4 sporocysts/ 2 sporozoites
birds, cattle, small ruminants, horses, rabbits, rodents, pigs

Question 23

Which species are zoonotic?

Answer 23

Giardia spp. (2); Trypanosoma cruzi (transmitted by Reduviid bug); Cystoisospora belli, C. natalensis (severe in AIDS patients), Cryptosporidium spp., Sarcocystis spp
.

Question 24

Eimeria bovis

Answer 24

calves susceptible
clinical signs: diarrhea, anorexia, dullness
easier to diagnose (fecal float)
gametogony causes majority of the damage
Type I schizonts macroscopic

Question 25

Eimeria zuernii

Answer 25

more severe, schizogony causes majority of the damage
bloody diarrhea
not as easy to diagnosis

Question 26

Cystoisospora suis

Answer 26

pigs
Found in: suckling piglets
Transmitted through: contaminated feces (direct life cycle)
Lives: sporozoites penetrate villous epithelium
Clinical signs: pasty/yellow diarrhea, no blood, dehydration
Diagnosis: biopsy of tissue

Question 27

Prevention of coccidiosis

Answer 27

reduce fecal contamination
automatic watering systems
keep area dry
separate older stock

Question 28

Cryptosporidium spp.

Answer 28

Zoonotic
Found in: intestine
Transmission: direct contact with oocyst, mucosal scapings/tissue, contaminated food/equipment, water
Susceptibility: calves < 3 weeks
Clinical signs: yellowy/watery diarrhea, anorexia, depression

Question 29

Methods that remove/kill cryptosporidium in water

Answer 29

reverse osmosis
distillation
filter 175o)
pasteurized drinks

Question 30

Toxoplasma gondii

Answer 30

obligate, intracellular parasite
DH- members of Felidae family
IH- most mammals
Transmission: acquired (oocysts), congenital (transplacental)
Lifecycle- DH: ingest tissue cyst/sporulated cyst or tachyzoite (any cells except RBC); IH: tachyzoites develop or bradyzoites develop
Clinical signs: fever, anorexia, jaundice, pancreatitis (cats); infective ovine abortion (sheep); abortions, fever, lethargy (goats)
Diagnosis: fecal floatation, IFA, ELISA
Control:

Question 31

Apicomplexan protozoans (ex. Eimeria, Toxoplasma gondii) do not produce eggs released in the feces of a final/definitive host, instead they produce:

Answer 31

oocysts

Question 32

Indicate whether the reproductive method listed is ASEXUAL or SEXUAL:
binary fission
sporogony
schizogony
gametogony

Answer 32

asexual
asexual
asexual
sexual

Question 33

The best way to diagnose Tritrichomonas foetus in a bull is:

Answer 33

smegma culture and direct smear

Question 34

The lifecycle of which parasite involves schizogony that occurs in macrophages of the vertebrate host:

Answer 34

Cytauxzoon felis

Question 35

Name the definitive host for Toxoplasma gondii.

Answer 35

member of the feline species