Unit 1 - Protozoa Flashcards
What is the name for bird-to-bird transmission of Histomonas meleagridis?
cloacal drinking
What bird type is the most susceptible to histomonas?
turkeys
Chickens that are infected intra-cloacally with Histomonas rarely:
show signs
What do histomonas lesions look like in the liver?
circular depressions of necrosis, enlarged
What do histomonas lesions look like in the ceca?
cecal core, ulceration –> perforation –> peritonitis
When can you see “Blackhead” symptoms appear in a bird that has been infected with Histomonas meleagridis?
~1 week after infection
What are some symptoms of H. meleagridis that can be seen 7-12 days PI?
lethargy, stilted gate, cyanosis
Mortality with H. meleagridis can occur how many days PI?
17 days
H. meleagridis can be more pathogenic if it is concurrent with these 3 infections:
C. perfringens, E. coli, Eimeria tenella
What are some rule outs for H. meleagridis?
Eimeria tenella, Salmonella spp., E. coli
What are the off-label drugs used to treat H. meleagridis?
dimetrodazole, metronidazole
Are there any approved drugs for treating H. meleagridis?
no
What off-label drugs are used to control cecal worm, Heterakis gallinarum?
fenbendazole, tramisol, hygromycin B
Which trichomonad can be seen in birds upper GI tract and liver?
Trichomonas gallinae
Which species does Trichomonas foetus infect?
cattle (urogenital), cats/dogs (LI), swine (intestine)
What are the general characteristics of the Trichomonad trophozoite?
3-5 anterior flagella, undulating membrane, axostyle, single nucleus, NO cyst stage, 4-30 um
Where is T. foetus located in female cattle host? male?
reproductive tract, vagina/uterus; sheath of penis, seminal vesicles, testicles
Where are T. foetus infections located in the actual fetus?
fluids from abortion, stomach of aborted fetus
Is the life cycle of Tritrichomonas direct or indirect?
direct
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
Clinical signs in male cattle with tritrichomonas:
asymptomatic
Clinical signs in female cattle with tritrichomonas:
repeat breeders (delayed estrus), infertility, vaginitis, cervicitis, chronic inflammation of vulva and vagina
What is the only stage in the life cycle of Tritrichomonas?
trophozoite
What are the characteristics of the Tritrichomonas trophozoite?
motile, flagellated, undulating membrane, 3 anterior flagella (10-26 um x 3-15 um)
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?
2
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