protozoa - apicomplexans - coccidia Flashcards
apicomplexans morphology
unicellular, eukaryote, organelles
apical complex: organelle at anterior end, help penetrate host cell
some have micropyle (small opening) and micropyle cap
Cystoisospora host
dogs, cats, pigs
Cystoisospora morphology
infective form = oocyte
-must be sporulated to be infective
-sporulated oocyte contains: 2 sporocysts, each sporocyst has 4 sporozoites
small, ovoid shape, no locomotion structures – glides
Cystoisospora source
-feces: fecal-oral cycle
-ingestion of sporulated oocysts from feces of infected animal, feces-contaminated food/water, infected paratenic host
-oocysts are NOT sporulated in FRESH feces (it takes hours/<1 day for sporulation to occur
Cystoisospora clinical signs
-often asymptomatic
-diarrhea: higher risk if - very young, stress, immunosuppression, other underlying disease
Cystoisospora pathology
-disease = coccidiosis
-intracellular pathogen
-invades small intestinal epithelial cells
-stunted intestinal villi –> decreased absorptive surface
-diarrhea
Cystoisospora diagnosis
-fecal float
-shed intermittently (recommend >1 test)
-identify oocysts: unsporulated in fresh, sporulated if hours old
what do sporulated Cystoisospora oocysts contain?
two sporocysts
each sporocyst contains 4 sporozoites
Cystoisospora treatment and prevention
-medication
-supportive care (hydration, nutritional support)
-good sanitation
-prophylatic treatment (swine)
-clean environment: oocysts are very resistant
steam clean, 10% ammonia solution
Cystoisospora zoonotic?
no; coccidia are species-specific
coccidian life cycle
PPP: 4-14 days
oocysts can be shed for 1-3 weeks
very resistant
3 phase of coccidian life cycle
- schizogony - asexual phase
- gamogony - sexual phase
- sporogony - maturation phase
schizogony
-asexual phase
-host ingests oocyst
-sporozoites exit oocyst
-infect host cell –>schizont
-multiple division –> produce merzoites
-repeated numerous times
gamogony
-sexual phase
-merozoites infect host cell and differentiate: male- micro gametocytes, female-macro gametocytes
-microgametocytes develop flagella
-fertilize macrogametocytes
-produce thick-walled oocyst
sporogony
-oocyst maturation phase
-sporocysts develop within oocyst
-sporozoites develop inside sporocysts
-takes hours/<1 day
-for most species, this is completed outside host
-once sporulation occurs, oocyst is infective
Eimeria host
species-specific, basically everything BUT cats and dogs
Eimeria morphology
-infective form = oocyst
-must be sporulated to be infective
-oocyst contains: 4 sporocysts; each sporocyst contains 2 sporozoites
everything else same as cystoisospora
Eimeria source and transmission
fecal-oral (no paratenic hosts)
Eimeria pathology
infects small intestinal epithelial cells
Eimeria diagnosis
id oocysts on fecal float
Eimeria treatment
medication
supportive care
Eimeria prevention
good sanitation
prophylactic treatment for food-producing animals (does not prevent infection but allows host to build immunity)
Eimeria zoonotic?
no
Cryptosporidium host
mammals, birds, reptiles, humans
Cryptosporidium morphology
-infective form = oocyst
-sporulate within host (immediately infection; auto-infection possible)
-sporulated oocyst contains: NO sporocysts, 4 sporozoites
-small
-spherical to oval
-no structures for locomotion
Cryptosporidium clinical signs
asymptomatic or diarrhea
Cryptosporidium source and transmission
fecal-oral
paratenic host
Cryptosporidium patho
infects gastric or small intestinal epithelial cells
Cryptosporidium diagnosis
PCR
acid-fast stain of fecal smear
ID oocysts on fecal float (difficult bc so small)
Cryptosporidium treatment
medication - non approved
supportive care
Cryptosporidium prevention
good sanitation
prevent ingestion of fecal-contamined food/water
Cryptosporidium zoonotic?
yes, but many are species specific
Toxoplasma gondii host
definitive = cats
paratenic = mammals
Toxoplasma gondii morphology
infective form = sporulated oocysts
-leaves host unsporulated
-must be sporulated to be infective (sporulates in 1-5 days)
-sporulated oocyst contains: 2 sporocysts, each sporocyst contains 4 sporozoites
-spherical shape
Toxoplasma gondii life cycle
3 important life stages
1. oocysts: shed in cat feces, develop in definitive host ONLY, infective after sporulating
- tachyzoites: within all hosts; multiply quickly; responsible for clinical signs
- bradyzoites: within cysts in all hosts; multiply slowly; infective if ingested
Toxoplasma gondii life cycle - paratenic/intermediate hosts
-schizogony: tachzoites – spread to tissues; bradyzoites – in tissue cysts
-no gamogony
-no sporogony
Toxoplasma gondii life cycle - definitive host
-schizogony: tachyzoites – spread to tissues; bradyzoites – in tissue cysts
-gamogony (sexual)
-sporogony (oocyst sporulation)
Toxoplasma gondii source
-oocysts: in feces of infect cats; fecal-contaminated water, food, soil
-tissue cysts: in tissues of infected paratenic host
-infected mother: transmitted to fetus
Toxoplasma gondii transmission
-ingestion: direct ingestion of sporulated cysts; indirect ingestion of paratenic host with tissue cysts containing bradyzoites
-transplacental: infection of female during pregnancy –> tachyzoites invade placenta, fetus
Toxoplasma gondii clinical signs
-diarrhea
-can disseminate via lymphatic and portal system to many organs and tissues:
brain –> encephalitis, CNS signs
lungs –> pneumonia
liver –> hepatitis
muscle –> muscle pain, stiffness
eyes –> inflammation, ocular disease
fetus –> abortion, CNS disease
Toxoplasma gondii pathology
acute disease
-GI signs, diarrhea: tachyzoites multiplying in intestinal cells
-tachyzoites invade other organs and tissues
chronic phase
-bradyzoites form tissue cysts: due to immune pressure from host
-few to no clinical signs
-tissue cysts may remain for life
-if host immune system wanes: tissue cyst can rupture; bradyzoites become active tachyzoites; disease recurs
Toxoplasma gondii diagnosis
-serology: measuring 2 antibody types - IgM and IgG
-fecal float: oocysts
-histopathology: biopsy - bradyzoites in tissue cysts; postmortem
-PCR
Toxoplasma gondii treatment
-medication
-supportive care
Toxoplasma gondii prevention
-prevent ingestion of sporulated cysts from cat feces
-prevent ingestion of bradyzoites: prevent predation, cook meat thoroughly
Toxoplasma gondii zoonotic?
yes
neospora caninum host
definitive - dogs
intermediate - many, like cattle, sheep, horses, goats
neospora caninum predilection site
definitive host - intestinal mucosa, CNS
intermediate host - repro system, nervous system
neospora caninum clinical signs
dogs: neurologic signs
cattle: major cause of abortions
sarcocystis host
definitive: carnivores
intermediate: herbivore (horses, cattle, sheep, goats)
sarcocystis predilection site
definitive host: GI tract
intermediate host: skeletal muscle
sarcocystis clinical signs
definitive host: myostits, GI, or neurologic signs
intermediate: usually asymptomatic
exception in horse: severe neurologic disease
hematozoon host
definitive: dogs
intermediate: ticks
hematozoon clinical signs
musculoskeletal- periosteal bone proliferation, joint and muscle pain
chronic wasting, death
