Toxoplasmosis Flashcards
What causes toxoplasmosis?
Obligate intracellular coccidian Toxoplasma gondii
Who are the definitive hosts of toxoplasmosis?
Cats only (completes the life cycle)
How long do cats shed oocysts in their feces for?
Sheds only one time during 1st exposure (3-5 days) and never again
How long do the oocysts survive in the environemnt?
Sporozoites in the environment develop into oocysts (infective) in 1-5 days (why litter box should be cleaned everyday)
In which species does the extraintestinal cycle occur?
Warm blooded animals (including cats)
- See systemic signs
- Schizophrenia, sexual arousal, attractiveness, etc.
In which species does the intestinal cycle occur?
Only in cats (most cats don’t get it)
- Diarrhea (lasts a couple of days)
How is toxoplasmosis transmitted?
Ingestion of infected animal tissues
- Primary source of infection in cats
- Dogs and humans: ingestion of meat byproducts, meat not well done)
Ingestion of oocysts in cat feces
- Source of infection for humans, dogs and rodents
- May also be from vegetables not washed well
Congenital (transplacental)
- Most severe clinical signs (kittens)
What are the clinical signs of toxoplasmosis?
- Cats infected for the first time: self-limiting small bowel diarrhea (2-3 days max)
- Acute toxoplasmosis: time of initial infection
-
Reactivation: secondary to immunosuppression
- Clinical signs from REACTIVATION, not reinfection
-
Non-specific signs: anorexia, depression, fever
- May be difficult to diagnose
- Acute necrotizing pneumonia
- Also uveitis, seizures, ataxia, icterus, myositis with hyperesthesia, stiff gait, and muscle pain
What are the lab changes seen with toxoplasmosis?
- CBC: non-specific
- Chemistry
- Increased ALT and ALP
- Increased CK and AST
How do you diagnose toxoplasmosis?
- Radiographs: interstitial pneumonia (sometimes alveolar), pleural effusion
- CSF: increase in protein and cell count (mostly small mononuclear cells)
- Demonstration of the organism (difficult)
- PCR (CSF or aqueous humor)- can also occur in normal cats
-
Serology- can also be positive in normal cats (used most of the time) ***
- IgG (stays for about 1 year)
- IgM (correlates better with clinical toxoplasmosis)
What is the difference in using IgM vs. IgG titers in a toxoplasmosis positive patient?
IgM
- Titers rise 1-2 weeks post infection
- Persists for less than 12 weeks
- Titers 1:256 suggest active infection
IgG
- Titers rise 2-4 weeks post infection
- Persist for longer than 1 year
- 4-fold increase over 2-3 weeks suggests active infection
How do you treat a patient positive for toxoplasmosis?
DOES NOT ELIMINATE ORGANISM (no microbiological cure)
- Supportive therapy
- Antimicrobials
- Clindamycin PO q12h (drug of choice) for 2-4 weeks
- Gram + antibiotic (Lincosamide)
- Side effects: V/D, anorexia
- Other options:
- Azithromycin PO q24h for 4 weeks
- Sulfonamide + trimethoprim PO q 12h for 2-4 weeks (cats that don’t tolerate Clindamycin)
- Clindamycin PO q12h (drug of choice) for 2-4 weeks
- Uveitis: topical corticosteroids (improves within 1 week)
- Treat secondary infections
- Clinical signs not involving CNS or eyes should resolve within 2-3 days
- Neuromuscular signs most difficult one to treat
- Partial resolution in 2 weeks
- May not be complete
- Prognosis not good
How do people get toxoplasmosis (zoonosis) and how can they prevent it?
- Ingestion of oocysts drinking contaminated water or working with soil
- Keep kid’s sandbox covered
- Clean litter box daily
- Wash vegetables well
- Tissue cyst ingestion (more important)
- Avoid eating raw meat
T or F. It is recommended to test all healthy cats.
False, testing healthy cats is not recommended
How can we prevent dogs from getting toxoplasmosis?
- Prevent them from coprophagia
- Do not feed them raw meat or undercooked meat byproducts
