Unit 1 - Protozoa Flashcards by Danica Wilson

What is the name for bird-to-bird transmission of Histomonas meleagridis?

cloacal drinking

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What bird type is the most susceptible to histomonas?

turkeys

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Chickens that are infected intra-cloacally with Histomonas rarely:

show signs

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What do histomonas lesions look like in the liver?

circular depressions of necrosis, enlarged

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What do histomonas lesions look like in the ceca?

cecal core, ulceration –> perforation –> peritonitis

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When can you see “Blackhead” symptoms appear in a bird that has been infected with Histomonas meleagridis?

~1 week after infection

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What are some symptoms of H. meleagridis that can be seen 7-12 days PI?

lethargy, stilted gate, cyanosis

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Mortality with H. meleagridis can occur how many days PI?

17 days

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H. meleagridis can be more pathogenic if it is concurrent with these 3 infections:

C. perfringens, E. coli, Eimeria tenella

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What are some rule outs for H. meleagridis?

Eimeria tenella, Salmonella spp., E. coli

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What are the off-label drugs used to treat H. meleagridis?

dimetrodazole, metronidazole

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Are there any approved drugs for treating H. meleagridis?

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What off-label drugs are used to control cecal worm, Heterakis gallinarum?

fenbendazole, tramisol, hygromycin B

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Which trichomonad can be seen in birds upper GI tract and liver?

Trichomonas gallinae

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Which species does Trichomonas foetus infect?

cattle (urogenital), cats/dogs (LI), swine (intestine)

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What are the general characteristics of the Trichomonad trophozoite?

3-5 anterior flagella, undulating membrane, axostyle, single nucleus, NO cyst stage, 4-30 um

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Where is T. foetus located in female cattle host? male?

reproductive tract, vagina/uterus; sheath of penis, seminal vesicles, testicles

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Where are T. foetus infections located in the actual fetus?

fluids from abortion, stomach of aborted fetus

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Is the life cycle of Tritrichomonas direct or indirect?

direct

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List the steps of the Tritrichomonas direct life cycle:

flagellated trophozoites introduced during coitus –> trophozoites reproduce asexually (via binary fission) in repro tract –> mature trophozoites in 14-20 days PI

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Clinical signs in male cattle with tritrichomonas:

asymptomatic

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Clinical signs in female cattle with tritrichomonas:

repeat breeders (delayed estrus), infertility, vaginitis, cervicitis, chronic inflammation of vulva and vagina

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What is the only stage in the life cycle of Tritrichomonas?

trophozoite

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What are the characteristics of the Tritrichomonas trophozoite?

motile, flagellated, undulating membrane, 3 anterior flagella (10-26 um x 3-15 um)

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Are there approved treatments for Tritrichomonas?

no, but Metronidazole has shown some efficacy

What are some control methods for Tritrichomonas?

control animal movement, test bulls annually (or before introducing to herd), AI, Cull positive cows, vaccinate females

What species does Tritrichomonas blagburni (foetus) infect?

cats

What is the likely transmission route of T. blagburni?

fecal-oral

Pathogenesis of feline Trichomoniasis:

large bowel inflammation (chronic diarrhea/relapes, hemorrhagic/mucoid stool)

What is the problem with treating feline trichomoniasis?

most unsuccessful (ronidazole is the treatment of choice)

What is the transmission for feline trichomoniasis?

cat to cat (grooming, litter boxes, feed, water); trophozoite survival

Site of infection in pigs with Tritrichomonas foetus:

stomach, colon, nasal passages (no pathology)

Site of infectioin in dogs with Tritrichomonas foetus:

LI (pathology - diarrhea)

What are the hosts for Trichomonas gallinae?

wide range of avian species

Trichomonas gallinae location in host:

primarily upper GI tract, extraintestinal

What are the characteristics of the Trichomonas gallinae trophozoite?

4 anterior flagella, undulating membrane, axostyle, single nucleus, no cyst stage, 5-9 um x 2-9 um

What is the life cycle of trichomonas gallinae (3 steps)?

trophozoites introduced orally --> divide (longitudinal binary fission) --> passed to next host orally

Routes of Infection for T. gallinae (4):

mother to offspring (regurgitation), water/feed contamination, predator/prey, courtship

What bird species is a reservoir host for Trichomonas gallinae?

pigeons

Pathology of Trichomonas gallinae (4):

upper GI tract (invade mucosal surface), caseous lesions, secondary infection, strain differences

Diagnosing T. gallinae (3):

gross lesion in throat, direct smear, histopath

Tx for T. gallinae

dimetronidazole (not available in US)

What two types of nuclei are seen in the ciliophora phylum?

macronucleus, micronucleus

List the 5 characteristics of Phylum Ciliophora:

two types of nuclei, ciliated body, food ingested through cytosome, reproduces by binary fission, majority are free livinig

What is the largest parasitic protozoan in humans?

balantidium coli (only ciliate known to parasitize humans)

What are the hosts for Balantidium coli?

pigs (primarily), humans, primates, horses, cows, rodents

What is the global distribution of Balantidium coli?

worldwide

Balantidium coli location in host:

Large Intestine

Does Balantidium coli have a direct or indirect life cycle?

direct

What is the life cycle of Balantidium coli?

Cyst in feces, ingested by host, trophozoites excyst in SI, colonize LI, encystation in LI; cyst and trophozoites excreted, cysts ingested

What is the infective stage of Balantidium coli?

cysts

How long is the Balantidium coli life cycle?

4-5 days

B. coli Reproduction:

transverse binary fission

B. coli route of infection:

fecal-oral

What shape is the macronucleus of trophozoite B. coli?

horseshoe

Pathology of B. coli in pigs:

usually asymptomatic, diarrhea, colitis (can also have ulcers in the stomach)

Pathology of B. coli in humans:

balantidiasis, chronic diarrhea, colitis, weight loss, ulcers, perforation of LI, concurrent infections

Tx of B. coli:

usually not treated

Ichthyophthiriasis

white spot disease

Most prevalent protozoan parasite of freshwater fish:

I. multifiliis

Parasitic fish stage of I. multifiliis:

motile ciliated trophont with a distinct horseshoe shaped macronucleus

Where are outbreaks and high mortalities most prevalent when dealing with I. multifiliis?

aquacultured fish species

What is the parasitic fish stage of I. multifiliis?

trophonts

What are the sites of infection associated with I. multifiliis trophonts?

gills, fins, skin

What stage of the I. multifiliis life cycle matures on the fish and then drops off into the water to become a tomont?

trophonts

What is the short summation of the I. multifiliis life cycle (4 steps)?

trophont --> tomont --> tomite --> theront

- protected and encysted stage in water | - binary fission within it produces tomites

tomonts (I. multifiliis)

- further develop into theronts | - release of theronts

tomites

- motile, ciliated stage - theronts emerge from the tomont into the water column - encounter a fish host

theront

How do theronts enter the fish host from the water?

penetrate into epithelium

How long do theronts have to contact a fish host before they die in the water?

48-72 hours (cooler temperatures can increase this window of opportunity)

What are the three main issues caused to the gills by the pathology of I. multifiliis?

O2 exchange compromised disruption of osmoregulation disruption of O2 uptake

Everything in this phylum have an "apical complex" in one stage that functions in host cell invasion

apicomplexans

Unicellular phylum of protozoa; some have tissue cysts containing many cells; spore-forming:

apicomplexans

Are apicomplexans direct or indirect in their life cycle?

can be either

asexual reproduction; a single zygote (in oocyst) produces infective sporozoites

sporogony

asexual reproduction; sporozoites undergo a rapid division to become meront (shizont) stages containing numerous invasive merozoits; several generations possible, depending on species

merogeny (schizogony)

merozoites differentiate into gametes (male microgametes and female macrogametes):

gametogony (gamogony)

gametes fuse to produce zygote (oocyst)

fertilization

What is the coccidian generic life cycle (8 steps)?

zygote --> sporogony --> sporozoites --> host cell invasion --> merozoites --> gamogony --> gametes --> fertilization --> zygote

What are the 3 main steps of the Eimeria spp. life cycle?

oocyst, sporulated oocyst, direct life cycle

How many sporocysts do sporulated Eimeria oocysts have? How many sporozoites?

4 sporocysts; each with 2 sporozoites

What part of the life cycle for Eimeria spp. infects target cells?

sporozoites

Does the Eimeria spp. have a direct or indirect life cycle?

direct (host --> environment --> host)

What factors contribute to Eimeria spp. pathology?

host, species, site of infection, challenge

What are the general clinical signs of Eimeria spp. infections (4)?

- severe, watery diarrhea, dehydration - bloody feces - loss of weight - lethargy/depression

What two Eimeria spp. are pathogenic to cattle?

bovis, zuernii

What are the clinical signs/pathology of Eimeria infections in cattle?

- severe, watery diarrhea - weight loss - lethargy/depression - lesions, submucosa destroyed

PPP for Eimeria spp. in cattle:

~2-3 weeks

What are the pathogenic Eimeria spp. for sheep?

E. ahsata, ovina

What are the pathogenic Eimeria spp. for chickens?

maxima, tenella

What are the pathogenic Eimeria spp. for cats/dogs?

not infected with Eimeria, have their own genus

How many sporulated Eimeria oocysts are there?

4 sporocysts, each containing 2 sporozoites

Cystoisospora can have an ________ stage in paratenic hosts:

extraintestinal

Does isospora/cystoisospora spp. have a direct or indirect life cycle?

direct

What is the Giardia PPP?

5-7 days

Asexual reproduction type for Giardia:

binary fission

Stages in giardia life cycle:

trophozoite, fecal cyst

Infective stage for Giardia duodenalis:

cyst stage in feces that can survive for months

G. duodenalis routes of infection:

fecal-oral, carnivorism

Where do the giardia trophozoites encyst?

large intestine

Giardia is spread through:

intermittent shedding

Where are Giardia trophozoites mainly located in the host?

Small Intestine

What is the size range for the Giardia trophozoites (motile stage w/ flagella)?

4-10 um x 10-20 um

How many nuclei do Giardia trophozoites have?

What should you look for in a direct smear when you suspect giardia? What stain should you use?

motile trophozoites; Lugol's iodine stain

What is the size range for Giardia fecal cysts?

4-10 um x 6-15 um

How many nuclei do giardia fecal cysts have (no flagella)?

4 nuclei

What is the typical diagnostic method for giardia fecal cysts?

flotation (w/ zinc sulfate or Sheather's solution)

What happens to giardia fecal cysts when subjected to Sheather's solution?

collapses them and gives them an ellipsoidal shape

Aside from a fecal float, what are the other diagnostic tests for testing for Giardia fecal cysts?

antigen test, Direct FA test, PCR

What are the four clinical signs associated with Giardia in dogs/cats?

small bowel, intermittent diarrhea; usually young animals; malabsorption, weight loss; mucus, fluid in small intestine (often associated with concurrent infections)

What are the clinical signs associated with Giardia in ruminants?

similar to dogs/cats but is not zoonotic

List the clinical assigns associated with human Giardia infection:

nausea, diarrhea, bloating, abdominal pain

List the three potential routes of infection for G. duodenalis human infection:

fecal contamination, contaminated water, usually human to human

What is the only environmental control against Giardia?

prevention of fecal build-up

What are some of the medications used to treat G. duodenalis?

metronidazole, albendazole, fenbendazole