Protozoa Flashcards
What protozoa causes coccidiosis in chickens and other hosts?
Eimeria spp.
- reason why commercial chickens are on a coccidiostatic
What 4 protozoans cause reproductive failure in various hosts?
- Toxoplasma gondii
- Tritrichomonas foetus
- Neospora caninum
- Sarcocystis cruzi
What 2 protozoans cause CNS disease?
- Toxoplasma gondii
- Sarcocystis neurona
What 7 protozoans have zoonotic potential?
- Babesia
- Balantidium
- Cryptosporidium
- Leishmania
- Giardia duodenalis
- Toxoplasma gondii
- Trypanosoma
General protozoan characteristics
- unicellular/multicellular stages
- eukaryotes with organelles
- aqueous/moist environment to feed and reproduce (many have a cyst stage)
- life cycles vary
- reproduction includes sexual and asexual stages
Identification is based on morphology of
- unique organelles, nucleus number/shape/size
- tissue cyst
- motile stages
- stages in RBC
- oocyst morphology
- gross lesions
What 3 protozoans have blood stages?
- Plasmodium
- Leucocytozoon
- Babesia
What is the causative agent of blackhead in turkeys?
Histomonas meleagridis
Giardia has _________ distribution
Worldwide geographical distribution
What is the most common flagellate of birds/mammals/reptiles/amphibians?
Giardia
Does Giardia have a direct or indirect life cycle?
Direct
- stages: trophozoite and fecal cyst
What type of reproduction does Giardia undergo?
Asexual
- binary fission
Infective stage of Giardia
Cyst stage in feces that can survive for months
- gets passed on in environment thru infected water/food or contaminated predator/prey
Routes of infection for Giardia
- fecal oral
- carnivorism
Is Giardia intracellular?
No
- just lays on intestinal villi
Giardia sites of infection
Small intestine
- trophozoites in small intestine (rarely in large intestine)
Trophozoites encyst in large intestine –> cyst stage excreted in feces
Animals infected with Giardia are __________
Intermittent shedders
- need 3 consecutive samples across 3 days to detect
Trophozoites
- size: 4-10 micrometers
- 2 nuclei
- flagellated
Giardia trophozoite diagnostic stages/techniques
Need a fresh sample from diarrhea!
- direct smear: look for motile trophozoites
- Lugol’s iodine stain
Fecal cysts
- size: 4-10 micrometers
- 4 nuclei, no flagella
Giardia fecal cyst diagnostic techniques
Flotation - zinc sulfate or Sheather's solution (collapses cyst) - antigen test (snap test) - direct FA test PCR
Giardia pathology dog/cat
- diarrhea, often intermittent
- affects young animals
- malabsorption, weight loss
- mucus, fluid in SI
- associated with concurrent infections
Giardia pathology ruminants
Primarily assemblage E!!
- high prevalence worldwide
- young most susceptible to acute infections
- chronic diarrhea, high morbidity
- adults chronically infected, reinfected
Giardia in humans is associated with
- Irritable bowel syndrome
- Chronic wasting
- Failure to thrive syndrome
G. duodenalis assemblages _____ infect humans, livestock, dogs, cats, wildlife
A/B
Giardia cysts are ______ infective
Immediately
Epidemiological factors
- water and food borne, mechanical/transport hosts
- population density, poor hygiene = potential for fecal contamination
- age/passive immunity - colostrum
- host specificity/reservoir hosts
Who is the reservior host for Histomonas meleagridis?
Chickens
- not pathogenic for chickens, but are a source of infection for turkeys
Histomonas meleagridis definitive host
Turkeys, chickens, pheasants, guinea fowl
H. meleagridis primary sites of infection
Liver and ceca
H. meleagridis life cycle
Direct
- Heterakis gallinarum (cecal nematode) eggs are required as a transport host
- Heterakis eggs are long lived in the environment, can survive for months
- H. gallinarum eggs are transported into bird host
H. meleagridis infective stage
Motile trophozoites
- found in H. gallinarum eggs
H. meleagridis route of infection
Ingestion of infected embryonated H. gallinarum eggs
H. meleagridis alternate route of infection
Paratenic host
- bird to bird transmission via cloacal drinking
Once H. gallinarum egg is ingested …
Egg hatches and H. meleagridis is released into intestine –> systemic via blood vessels –> liver, ceca (where trophozoites undergo binary fission)
In the ceca: H. meleagridis infects Heterakis gallinarum female and is incorporated into nematode eggs
Blackhead
Lethargy, stilted gate, cyanosis occurs 7-12 days post infection
- mortality 17 days post infection
H. meleagridis lesions
Liver: circular depressions of necrosis, enlarged
Ceca: cecal core, ulceration –> perforation –> peritonitis
H. meleagridis is more pathogenic with _______
Concurrent infections
- C. perfringens
- E. coli
- Eimeria tenella
H. meleagridis diagnosis
- clinical signs
- cultivation is difficult
- pathology/histology: lesions in liver/ceca
What are the 3 rule outs for H. meleagridis?
- Eimeria tenella
- Salmonella
- E. coli
H. meleagridis treatment
- no approved drugs
- control of Heterakis gallinarum
- avoid co-habitation of bird species, problem with free range birds
General trichomonad characteristics
Trophozoite
- 3-5 anterior flagella
- undulating membrane (motility)
- axostyle
- single nucleus
- no cyst stage
- 4-30 micrometers
- *do not have a cyst stage!**
Most trichomonad species are not _______
Pathogenic
- intestinal/high numbers
Tritrichomonas foetus
Infect cattle worldwide
- endemic in free-ranging herds
- causes trichomonad abortions, trichomonosis
T. foetus location in host
- female: repro tract (vagina/uterus)
- male: penis sheath, seminal vesicles, testicles
- fetus: fluids from abortion, stomach
Bulls are considered to be carriers ______ once a diagnosis is made
For life
- young bulls: less likely to transmit
- bulls over 3 yrs are greater risk due to higher surface area
Tritrichomonas life cycle
Flagellated trophozoites introduced during sex –> trophozoites reproduce asexually in repro tract (binary fission) –> mature trophozoites in 14-20 days post-infection
- direct life cycle
- *no cyst stage**
Tritrichomonas foetus clinical signs
Males: asymptomatic
Females: infertility, vaginitis, cervicitis, chronic vaginal inflammation
Fetus: aborted within 16 weeks
Tritrichomonas diagnostic stage
Trophozoite
- motile, flagellated, undulating membrane, 3 anterior flagella
- presence on wet mounts
- sample from repro tract on saline
- culture: in pouch TF system
- combine: culture, PCR, wet mounts
Tritrichomonas - treatment/control
No approved drugs
Control
- test before introduction of bull/cows
- AI
- test bulls annually –> neg bull requires 6 consecutive negs or 3 negs over several weeks
- cull positive cows and vaccinate females
Tritrichomonas blagburni (foetus)
Feline trichomoniasis
- intestinal trichomoniasis in cats (large intestine)
- blagburni and foetus are genetically distinct
Tritrichomonas blagburni transmission
Trophozoites transmitted via fecal/oral route
- binary fission in large intestine
- young, pure-bred show cats, and group housed cats at greater risk
T. blagburni and T. foetus cross transmission studies
- cattle isolate in cats = low infection, less pathology
- cat isolate in cattle = less pathology
T. blagburni pathogenesis
Large bowel inflammation
- “large bowel disease”
- chronic diarrhea (relapses)
- hemorrhagic, muccoid stool
T. blagburni diagnosis
History of diarrhea
- -> FIV, corona virus, FeLV, cryptosporidium, giardia
- motile trichomonads in feces
- culture (in pouch), PCR
What are 2 rule outs for Tritrichomonas blagburni?
- giardia
- pentatrichomonas hominis
Feline tritrichomoniasis treatment/control
Unsuccessful treatments
Control: isolation of cats, repeat testing
T. blagburni transmission
Cat to cat
- grooming, litter boxes, feed, water
Tritrichomonas foetus other hosts
Swine - site: stomach, colon, nose - no pathology Dogs - site: large intestine - pathology: diarrhea Humans - one case
Trichomonas gallinae
Infects wide range of avians
- located in upper GIT, extraintestinal
T. gallinae trophozoite
- 4 anterior flagella
- undulating membrane, axostyle
- single nucleus
- no cyst stage
Trichomonas gallinae life cycle
Trophozoites introduced orally –> divide via binary fission –> passed to next host orally
T. gallinae routes of infection
- mother to offspring via regurgitation
- water/feed contamination
- predator/prey
- courtship
- pigeons may be reservoir hosts
Trichomonas gallinae pathology
“Canker”, roup, frounce, trichomoniasis
- upper GIT –> invade mucosal surface
- caseous lesions
- secondary infection
- strain differences
T. gallinae diagnosis
- gross lesion
- direct smear
- histopathology
