12 – Protozoa II Flashcards
Toxoplasma gondii
- Felids only DH
- Wide range of vertebrates=facultative IH (cats, dog, people)
- Seroprevalence: 15-30% in humans
Toxoplasma sporulated oocysts
- Oocysts produced for only a few weeks ONCE in cats lifetime
- Can be 100 million per cat
- Survive in moist soil for 1 year, 5 years in water
- *4 in 2
- Differential diagnoses: Cystoisospora, Hammondia
Toxoplasma: Tachyzoites in Peritoneal Fluid
- Another infective form
- Divide fast in a naïve hosts
- Can be anywhere in the body
- *if host is eaten=infective
Toxoplasma: Tissue Cyst with Bradyzoites in Brain
- Thin walled tissue cyst
- Dived slower, but continue to divide
- Will be found intracellularly for the rest of an animals life
- Still same ‘shape’ as Tachyzoites but in a cyst form
- *also in skeletal muscle
- *stay in cysts unless immunocompromised and they are released for some reason
Toxoplasma felid gut reproduction
- Oocyst ruptures and oocyst sporulates
- Merogony
- Gametony
- *unsporulated oocysts into environment
- *ONLY IN CATS
What is the route of feline infection? (3)(Toxoplasma)
- Fecal-oral route: 21days (PPP=21 days) (sporulate 1-3 days)
- Infect IH from being eaten (PPP=3-8 days)
- transplacental transmission to litter of queen INFECTED FOR FIRST TIME in pregnancy (or lactating)=most severe disease (for the kittens)
What are the symptoms in congenitally infected kittens? (Toxoplasma)
- Ocular lesions
- Neurological lesions (encephalitis)
- Anorexia
- Lethargy
- Diarrhea
- Pneumonia
- icterus
Pathogenesis of Toxoplasmosis
- Adult cats: self-limiting diarrhea, fever
- Most severe in congenitally infected kittens
- In <10% of cats, infection may recrudesce (reoccur) or may be reinfected
o May shed low # oocysts sporadically - IH: asymptomatic (can transmit through carnivory and vertically)
- Dogs: acutely infected in pregnancy may abort
Vertically transmission of Toxoplasmosis ONLY occurs when
- Mother is infected for the FIRST time
Humans and the Toxoplasmosis life cycle
- Food borne: if eat eggs shed in stool
- Organ transplants and blood transfusions
- Transplacental or transmammary: if INFECTED for first time
Diagnosis of Toxoplasmosis
- Fecal floatation: oocysts only shed for 2 weeks
- Serology, immunohistochemistry, PCR
Control of Toxoplasmosis
- Clean litter boxes daily (before sporulation)
- Keep cats indoors
- Feed only commercial, cooked or frozen (-18degrees C for at least 3 days)
When do you treat Toxoplasmosis?
- Only acute disease
- To reduce risk of congenital transmission
- To avoid reoccurrence
Risk assessment and mitigation of T. gondii for pregnant owners
- Avoid cleaning litter box, gardening, consumption of raw uncooked meat, raw milk, unwashed produce and unfiltered water
- <1% of cats shedding at a give time: young, outdoor
- *for highly concerned owners: consider serology
- *prevention for cat: only commercial diet or cooked foods
Serology for T. gondii and pregnant owners: best and worst case scenario
- BEST: positive for cat and human (cat unlikely to shed and owner protected)
- WORST: negative for cat and human (HIGHEST level of prevent from cat and owner)
Neospora coninum
- DH: dogs and wild canids
- IH: cattle, wild ungulates, other carnivores (cats)
o NOT infected through carnivory - *NOT zoonotic
Neospora sporulated oocyst from dog feces
- Differntial:hamondia?
Neospora tissue cyst in neuron or skeletal muscle
- *has a THICK WALL cyst=can see the edge
Neospora tachyzoites from cutaneous aspirate of dog
- Some dermatitis forms (USUALLY OLDER DOGS)
- Looks the same as Toxoplasma
Life cycle of Neospora caninum
- DH: dogs (same system in intestines and transplacental)
- Release of sporulated oocyst (1-3days, 3 week patency)
o Infect another dog? Not sure.
o Ingested by cattle (or other ungulates) - Tachyzoites and bradyzoites: tissue cysts and transplacental
o Can cause abortion in cattle if early pregnancy - Dogs can eat aborted fetus or placenta
- **IH DO NOT TRANSMIT IT TO ONE ANOTHER
Pathogenesis of Neospora
- Often asymptomatic
- Not all pups infected with tissue cysts
- Not all infected show signs (reactivate and infect (like Toxocara canis)
- *can infect subsequent litters
- Most SEVERE in congenitally infected
Pathogenesis of Neospora: congenitally infected
- Neurological and skeletal muscle
- *progressive hindlimb paralysis
- *dysphagia
Pathogenesis of Neospora: older dogs
- Encephalitis
- Myopathy
- Ulcerative dermatitis
Diagnosis of Neospora in dogs
- Clinical appearance
- Serology (serum, CSF): IFAT, ELISA
- Histology/cytology and IHC; PCR
Control of Neospora in dogs
- Do NOT allow dogs to eat placenta, fetus or dead calves
- Do NOT breed SEROPOSITIVE female dogs
- Sulphonamides, clindamycin
Sarcocystis spp.
- *Global
- Require carnivore IH
- ‘named’ according to DH and IH host
- *dogs and cats are often DH but can be IH (unknown lifecycles)
Sarcocystis spp. parasite web
- Gametogony and sporogony in DH (pets)
- Sporulate in intestines and shed in feces (sporocyst with 4 sporozoites=smaller)
o Immediately infective - Develop in IH: merogony
- Sarcocysts with bradyzoites (in muscles) and eaten by dogs and cats
Sarcocystis sporocyst from feces
- COMMON in dogs in western Canada
- Means dog has access to raw meat or wildlife
Sarcocystis pathogenesis: pet perspective
- None as DH, some as IH
o Hepatitis
o CNS
o myositis
Sarcocystis diagnosis: pet perspective
- fecal floatation (DH)
- serology, muscle biopsy (IH)
Sarcocystis control: pet perspective
- do NOT feed raw meat and organs
- prevent access to wildlife (tissues and feces)
Sarcocystis zoonotic potential: pet perspecitve
- NONE in Canada
- Humans serve as DH for cattle and pig Sarcocystis (not in Canada)
Haematozoea
- Arthropod transmitted
o Ticks, mosquitos, black flies - Bad infections=high mortality rates
Haematozoea: indirect life cycle (Babesia)
- DH: Tick
o Sexual reproduction in gut
o Sporogony in salivary glands (sporozoites) - Blood feed on IH mammal (cattle, sheep, horses, dogs, cats)
o Asexual reproduction in erythrocytes
o *picked up when tick blood feeds - **NOT in Canada
Amoebae
- Direct life cycle: asexual reproduction
- Trophozoite=infective stage
- *free living amoeba
o In water: people and dogs go swimming and it goes through the nose and past BBB
o Hard to diagnosis=often fatal
