protozoa 2 dogs and cats Flashcards
Tissue cyst of coccidia
-Toxoplasma
-Neospora
Toxoplasma gondii
-Felids only DH
-Wide range of vertebrates serve as facultative intermediate hosts
-seroprevalence 15-30%
Toxoplasma oocysts
-oocysts produce for only a few weeks once in a cats lifetime
-100s of millions per cat
-survive in soil for 1 yr, water for 5yrs
Tachyzoites
-located in peritoneal fluid
-fast dividers
Bradyzoites
-located in brain and muscle
-thin walled tissue cysts
Toxoplasma reproduction in felid
- Merogony
- Gametogony
- Unsporulated oocysts pass in feces
Route of feline infection- fecal oral route
-fecal-oral route
-PPP:21 days
- Eggs shed in feces from felid
- Sporulation 1-3 days
- Cat ingests
Ingestion of oocysts by intermediate hosts
- Intermediate hosts ingest eggs from cat feces
- Become tachyzoites that then cyst in tissues as bradyzoites
PPP=3-8 days
Transplacental transmission of toxoplasma to litter
*occurs if queen is infected for first time in pregnancy
SEVERE DISEASE
Tachyzoites will be shed that passes on
Symptoms to kittens: ocular lesions, neurological lesions
Pathogenesis of Toxoplasmosis
Adult cats: self limiting diarrhea, fever
Kittens: most severe when congenitally infected (anorexia, lethargy, diarrhea, pneumonia, icterus, encephalitis, ocular lesions)
Intermediate hosts: often asymptomatic; can transmit vertically and through carnivory
Ex. dogs infected in pregnancy= may abort
**Reinfection may occur
How long does shedding of toxoplama last?
2 weeks
Diagnosis of toxoplasmosis
-Fecal flotation (oocysts only shed 2 weeks)
-Serology, immunohistochemistry, PCR
Control of Toxoplasmosis
-clean litter boxes daily before sporulation
-keep cats indoors
-feed pets only commercial, cooked or frozen (-18 for 3 days) diets
Treatment for toxoplasmosis
-Only for acute disease; some drugs
-reduce risk of congenital transmission
-treat and avoid reinfection
Risk mitigation for owners
-Avoid cleaning litter boxes
-Gardening
-consumption of undercooked meat
-raw milk
-unwashed produce and unfiltered water
-less than 1% of cats shedding at any given time
Neospora caninum hosts
DH: dogs and wild canids
IH: cattle, wild ungulates, other carnivores, cats
*not zoonotic
Neospora oocyst
-located in dog feces
-contains 4 sporozoites in each of a total 2 sporocysts
Neospora tissue cyst
-located in neurons, skeletal muscle
-very thick walled cyst
Life cycle of Neospora caninum
- DH dogs and wild canids
- Release oocysts in feces. Sporulates in 1-3 days. Patency=3wks
- IH ingest sporocysts
- DH ingests tissue cysts of IH or the placental abortus from IH
**Transplacental infection in both DH and IH
**IH cannot pass to each other
Pathogenesis of Neospora
-often asymptomatic
-not all pups infected with tissue cysts, and not all infected show signs
-can infect subsequent litters. Most severe in congenitally infected puppies (neurological and skeletal muscle issues such as hindlimb paralysis, dysphagia)
-older dogs: encephalitis, myopathy, ulcerative dermatitis
Diagnosis of neospora
-clinical appearance
-serology
-histology/cytology
Control of neospora
-do not allow dogs to eat placenta, fetus, or dead calves
-do not breed seropositive female dogs
-Drugs: sulphonamides, clindamycin
Sarcocystis spp life cycle
- Carnivore DH; gametogony, sporogony. Sporulation occurs in the intestines
PPP:1 wk - Sporocysts with 4 sporozoites in feces
*immediately infective - Ingested by IH: merogony. Develops for at least 2 months
- Sarcocysts with bradyzoites in tissues of IH
- DH ingest bradyzoites in muscle of IH
Sarcocystis sporocyst
-most common in West
-likely dog has access to raw meat or wildlife
Control of sarcocystis
-do not feed raw meat
-prevent access to wildlife
-not a zoonoses issue in Canada; humans are a DH for cattle and pig sarcocystis
Diagnosis of Sarcocystis
-Fecal float
-serology
-muscle biopsy
Haematozoea
-arthropod transmitted
-ex. Hepatozoon, Cytauxzoon
1.IH mammal; asexual reproduction in erythrocytes
2. DH tick takes blood meal. Sexual reproduction in gut.
3. sporogony in salivary glands of DH
4. IH will ingest the tick
Amoebae in dogs and cats
Direct life cycles
-amoeba living in warm water; travel up nose through brain plate
-trophozoite infective stage
-free living amoeba in humans and dogs
-eg. Naegleria