infectious dz: Cat 4 Flashcards
Who is the definitive host of toxoplasma, tritichomonas, and cytauxzoon spp?
Cats
*intracellular protozoan parasites found world wide
What are the three infectious stages of toxoplasma gondii?
Sporozoites in oocysts (found in feces)
tachyzoiets (actively multiplying)
Bradyzoites (slow multiplying stage - enclosed in a tissue cyst)
What is the mode of transmission of toxoplasma gondii?
Congenital infection
Ingestion of infected tissue
Ingestion of oocyst (contaminated food/water)
Lactation, transplantation, +/- vectors
In what animals is there a higher prevalence of toxoplasma?
More prevalent in older animals (they have greater chance of exposure)
High prevalence in animals fed a raw meat diet
What is the life cycle of toxoplasama in a definitive host?
- Ingests bradyzoites in meat of intermediate host
- Bradyzoites released by digestive enzymes
- They penetrate epithelial wall and undergo sexual reproduction
- Form micro and macrogamounts - undergo sexual repro
- OOcyts will be passed out in feces - and will sporulate after being exposed to air and moisture for 1-5 days –> two sporocyts -> four sporozoites
What is the extra intestinal life cycle of toxo gondii?
- Ingestion fo oocyst or tissue cyst
- Sporozoites released and penetrate intestinal mucosa
- Divide into tachyzoites - reproduce intracellularly for undetermined time
- Eventually they will encyst –> bradyzoites will be stage within tissue cyst (muscle, visceral organs, CNS)
What cat owners should be most concerned with toxoplasma infections?
Pregnant women
What are common sites for persistent toxoplasma gondii infections?
brain liver lung muscle eyes
*initial replication and chronic persistent infections
What host factor will determine if a patient will develop clinical toxo?
Their immune system!
Immunosuppression or concomitant infection (FeLV, FIV, FeCoV/FIP) will make the patient more susceptible
What cat population infected with toxoplasma gondii will develop self limiting small bowel diarrhea?
Naive cats that ingest bradyzoites
usually lasts up to 10 days (or can be clinically silent)
Transplacentally or lactationally spread toxoplasma will result in _____ spread in infected kittens
systemic
*kitten fading syndrome
:(
Inflammation of the lungs, liver, CNS
Enlarged abd - hepatopathy and ascites
Ocular signs - chorioretinitis/anteriors uveitis
What clinical signs may be noted in older cats with reactivation of chronic encysted infection?
This occurs when the cat becomes immunosuppressed - bradyzoites will be released
*anorexia, wt loss, lethargy, dypsnea, myocarditis, vomiting/dhr, abdominal effusion, painful muscles - stiff gait, lameness
neuro - anterior or posterior uveitis, iritis, lens lux.. ataxia, circling etc
T/F: Toxoplasma gondii should be a ddx in older cats with neurological signs
TRUE
What changes will you see on CBC/Chem in a cat with clinical toxoplasma infection?
Non-regen. anemia, neutrophilic leukocytosis, lymphocytosis, monocytosis, eosinophilia
Increased AST/CK (muscle necrosis), Increased ALT/ALP/Bilirubin (hepatic necrosis), hyperglobulinemia, increased amylase/lipase (pancreatitis)
What stage of toxoplasma might you see on the cytology prepared from a muscle FNA?
Tachyzoites - this stage is mobile and replicating
cysts –> bradyzoites
What might you see on chest rads of a toxoplasma positive cat?
Diffuse interstitial to alveolar pattern with a mottled lobar distribution
T/F: A fecal examination is a good method for identifying toxoplasma oocysts
FALSE
less than 1% of cats shed oocysts
Multiple serological tests for antibodies are required to confirm a toxoplasma infection from most samples, but from what samples does the presence toxoplasma of antibodies mean the patient definitely has a toxoplasma infection?
Antibodies in the eye or brain
If the cat just has antibodies from exposure to toxoplasma - those ABs would not be present in the brain/eye or cross those barriers
What is the ELISA test for toxoplasma testing for?
ANTIGEN
Other tests available - Culture of tissue or body fluids / PCR - can not differentiate a chronic subclinical cat from an acute infection
What is the recommended treatment of toxoplasma gondii?
Clinical toxo: Clindamycin BID x 4 weeks
Pyrimethamine and sulphonamide combination
To reduce oocyst excretion: monensin, toltrazuril
What methods of prevention can be used for toxoplasma gondii?
Keep cats indoors
Do not feed raw diets
Prevent cats entering areas where food-producing animals are housed
What clinical signs may be seen in a cat with tritrichomonas foetus?
Waxing/waning large bowel dhr (mucoid, very frequent, hematochiezia, straining)
In what cat population is T. foetus more prevalent?
More prevalent in younger cats but can be seen in all ages
How do cats get T. foetus infections?
Spread cat to cat through shared litter boxes
What is the best method of diagnosing Tritrichomonas foetus?
Fecal PCR
Others - fecal smear, culture using special growth media (kits are available for cows)
What is the treatment of choice for Tritrichomonas infections?
Ronidazole x 14 days
side effects - lethargy, inappetance, ataxia, sz
Where is Cytauxzoon felis most prevalent geographically in the US?
South eastern and mid atlantic regions
What are the vectors of Cytauxzoon ?
Amblyomma americanum and Ripicephalus sanguineus
What age group is most susceptible to Cytauxzoon infections?
ANY AGE, gender, or breed
T/F: Immune suppression is not required for cats to have clinical Cytauxzoon infections
TRUE
Where do Cytauxzoon organisms replicate in the body?
Asexual schizogenous repro occurs within the hosts mononuclear phagocytic cells (causes vasculitis and vascular obstruction)
Cells eventually rupture, releasing merozoites which are taken up by RBCs –> hemolysis
How soon after Cytauxzoon dz transmission do clinical signs occur?
1-3 weeks
What signs will be noted with acute onset of Cytauxzoon, and in what season is that most commonly noted?
Anorexia, lethargy, fever predominantly in the spring and summer
progresses to increased vocalisation, weakness, icterus, dark yellow urine, resp. distress, obtunded mentation and seizures
Severe pyrexia (103-107F) DIC
T/F: Cats that survive the acute phase of Cytauxzoon may be chronic carriers of piroplasms in erythrocytes
TRUE
clinically recovery is complete - but they can be carriers
What test(s) can be used to diagnose Cytauxzoon felis?
CBC/Chem - pancytopenia, anemia, indicators for DIC
May see organisms on peripheral blood smear (piroplasma - ring shaped) May see schizonts in monocytesin the feathered edge
Schizont laden macrophages may be noted in bone marrow aspirate
PCR - to confirm presence of parasite
What therapy is recommended for Cytauxzoon infections?
Supportive care, +/- antiprotozoal meds = Imidocarb IM (2 inj 14 days apart) or Atovaquone and azithromycin
***PREVENT TICK EXPOSURE
What fungal infection are cats highly susceptible to?
Sporothrix schenkii
What clinical signs are associated with Sporothrix schenkii infections in cats?
Some are subclinical
- single skin lesion that may regress
- Fatal systemic form - hematogenous spread
***most common - multiple skin and mucosal lesions (mostly on the head) conjuctival, nasal, oral, genital
What cats are predisposed to Sporothrix schenkii infections?
Intact, sexually active cats
Males»» females
What is the treatment for sporothrix schenkii?
Itraconozol and topical potassium iodide solution
