Protozoa Flashcards
Characteristics of Protozoa
- 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
Protozoan classification
Kingdom: Protista
Phylum: Sarcomastigophora/Apicomplexa/Ciliophora*/Microspora
Protozoan reproduction
Asexual and Sexual Binary fission- longitudinal/transverse, asexual Multiple fission/schizogony Budding Conjugation Syngamy-sexual
Protozoan nutrition
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
Giardia spp.
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
Trophozoite
motile
four pairs of flagella
seen moving through direct fecal smear
Resistant cyst stage
oval, thick refractile wall
occupy one end of the cyst
Tritrichomonas spp.
flagellates; adapted to live in anaerobic environment, most don’t cause disease
Characteristics of Trichomonads
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
Pelta
sheet of microtubules that function as support for anterior flagella
Axostyle
consists of simple or multilayered ribbons of microtubules that function as an internal cytoskeleton
Parabasal body
trichomonad Golgi apparatus
Blepharoplast or Basal body
centrosome-like structure from which the flagellum arises
Costa
support for undulating membrane
Hydrogenosome
spherical structure, commonly found along the axostyle and costa; functions as calcium store and producer of ATP and H+
Bovine Genital Trichomoniasis
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
Feline Trichomoniasis
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
Trypanosoma cruzi
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)
Characteristics of Trypanosomes
kinetoplast pleomorphic cytoskeleton single nucleus elongated cell body- single flagellum; rounded cell body- short flagellum
Apicomplexa
distinct nucleus, subpellicular tubules
apical complex
orders: Eucoccidiida, Piroplasmida
Cystoisospora (Isospora)
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)
Eimeria spp.
Stenoxenous/Monoxenous
Worldwide
Organ specificity
Asexual and Sexual reproduction
Sporulated oocysts- 4 sporocysts/ 2 sporozoites
birds, cattle, small ruminants, horses, rabbits, rodents, pigs
Which species are zoonotic?
Giardia spp. (2); Trypanosoma cruzi (transmitted by Reduviid bug); Cystoisospora belli, C. natalensis (severe in AIDS patients), Cryptosporidium spp., Sarcocystis spp
.
Eimeria bovis
calves susceptible clinical signs: diarrhea, anorexia, dullness easier to diagnose (fecal float) gametogony causes majority of the damage Type I schizonts macroscopic
Eimeria zuernii
more severe, schizogony causes majority of the damage
bloody diarrhea
not as easy to diagnosis
Cystoisospora suis
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
Prevention of coccidiosis
reduce fecal contamination
automatic watering systems
keep area dry
separate older stock
Cryptosporidium spp.
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
Methods that remove/kill cryptosporidium in water
reverse osmosis
distillation
filter 175o)
pasteurized drinks
Toxoplasma gondii
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:
Apicomplexan protozoans (ex. Eimeria, Toxoplasma gondii) do not produce eggs released in the feces of a final/definitive host, instead they produce:
oocysts
Indicate whether the reproductive method listed is ASEXUAL or SEXUAL: binary fission sporogony schizogony gametogony
asexual
asexual
asexual
sexual
The best way to diagnose Tritrichomonas foetus in a bull is:
smegma culture and direct smear
The lifecycle of which parasite involves schizogony that occurs in macrophages of the vertebrate host:
Cytauxzoon felis
Name the definitive host for Toxoplasma gondii.
member of the feline species
