11. Protozoal Disease Flashcards
What does EPM stand for?
Equine Protozoal Myeloencephalitis
What is the causative agent of EPM?
Sarcocytis neurona
Neospora hugesi
What is the definitive host of the causative agent of EPM
Opossum
What kind of host is the horse for Sarcosystis neurona and neospora hugehsei?
Dead end
Can not transmit disease so dont need to worry about other horses getting it
What is the lifecycle of Sarcosytis neurona?
Definitive Host: Opossum
Poop out in feces
Ingested by intermediate hose then sarcocysts in skeletal muscle or by horse them lesion in brain or spinal cord
What is the prevalence of EPM?
Widespread exposure 40-60% but less than 1% of horses develop the disease (dose related, strain and immune responses)
What are some factors involved with horses that get EPM?
Stress
Season
Location
Age
Other diseases
What are the clinical signs of EPM?
Depend on part of CNS affected
-Multifocal or focal
-Top differential for CNS disease in horse
Ataxia, Asymmetric, Atrophy
-Slowly progressive (can be acute and severe)
What are the key points in diagnosing EPM?
- Confirm clinical signs (neuro!!!)
- Rule out all other diseases
- Confirm with intrathecal antibody production
How do you determine if a horse has clinical signs consistent with EPM?
Neurologic Exam
Lameness Exam
-Localize the lesion and grade it
An owner is concerned about EPM when purchasing a horse. She wants you to test for EPM on her prepurchase exam…what should you tell her?
You should not test unless you have clinical signs of disease because it will most likely be positive due to the prevalence in our area and high chance of exposure
What are some diagnostics you should do to rule out other diseases?
Lameness exam
CBC/Chem
Serology
Rad/Myelogram
CSF - cytology
What are some diseases you should be ruling out?
EHV, Encephalitis, Compressive Spinal Cord Disease
What do the following diagnostics look like on a horse with EPM?
Hematology and BioChem:
CSF:
Hematology and BioChem: Normal
CSF: Cytology normal, test S. neurona antibodies , abnormal cytology doesnt rule out EPM but other more likely
What are some immunodiagnostic tests you should run on serum when testing CSF for EPM?
Western Bot
Elisa - SAGs
IFAT
What is the issue with serum testing for EPM?
High prevalence of exposure
Low prevalence clinical disease
Low positive predictive Value
Negative predictive high unless in early disease (retest 10-14 days)
Testing CSF improves accuracy and titer helps more
Why can a ratio of serum antibodu titer to CSF antibody be useful in diagnosis of EPM?
This ratio helps to identify if the antibodies in the CSF were made there or if they just diffused in from the blood.
For the IFAT test, does the titer correlate with the probability of active infection?
No, more likely the amount exposure, chronicity exposure and individual immune response
When using the SAG Elisas to test for EPM which are the most reliable and accurate?
2, 4/3
What id the treatment for EPM?
Antiprotozoal Drug - sulfadiazene, pyrimethamine, ponazuril, marquis, protazil, supportive care, biological response modifiers
How long do you have to treat with SDZ/PYR? What are some side effects?
90 days
Diarrhea, leukopenia, anemia, fetal abnormalities
$150 a month
How does treating with ponazuril work?
Loading dose with vegetable oil
90 day treat
no toxicity
$1000 a month
How much does protazil cost? what is it most like?
$800
Ponazuril
What type of supportive care should be given in treatment of EPM?
NSAIDS
DMSO
Dexamethasone
Vitamin E
