Parasitology - Lecture 23 (Horse Protozoa) Flashcards
Break down the different categories of Horse protozoa into the different categories and sopecies involved
Two mian categories: APicomplex and Flagellates
APicomplexa is broken down into Coccidia and Hemoprotozoa
- Hemoportozoa –> Babesia and Theirleria
- Coccidia –> Sarcocystis nuerona; Neospora spp; Eimeria Leuckarti
Flagellates includes TrTrypanosoma equiperdum
Which speciees of prtozoa is inovled in Equine protozoal myeloenchpalitis
Equine Protozoal Myeloencephalitis is a neurologic disease of horses caused by protozoans knwon as Sarcocystis neurona and it appears that Neopsora caninum is involved in this diease too
Discuss the lifecycle for EPM (Equine protozoal myeloencephalitis)
- Since EPM is caused by sarcocystis neurona, the life cycle goes as follows: Neospora caninum may or may NOT be included in this lifecycle description, im not sure
- opossum –> efinitive host for S. neurona
- Opossum shed oocysts in feces –> contaminate food/water –> skunk, cats, armadillos, racoons ingest and develop asexual sarcocysts in muscles –> eaten by opossums
- skunks, cats, armadillos, racoons –> ingest oocysts (intermediate host); asexual reproduction; sarcocysts in muscle
- ## Horses are the accidental (dead-end) host (aberrant )
Whats important about EPM and opossum feces
- ## Sarcocystis neurona oocysts ONLY in opossum feces
Discuss the life cycle for Neospora cnainum and its relation to EPM
- Dog defintive host –> produces oocysts that cinbtaminate ruminant feed/water –> cattle bradyzoite tissue cysts
- Then i think horse inadvertently ingests oocysts –> dvelops into asexual schizont stages in CNS
Discuss the pathogenesis and clinical signs of EPM
Horse is dead end host
- Replicates in central nervous system –> brain and spinal cord
Nuerologic signs:
- depression
- Head tilt
- Facial paralysis
- Leaning
- Ataxia
- Lethargy
- Muscle atrophy
- Weakness
Discuss the diagnosis of EPM
Antemortem diagnosis is based on clinical signs
May rule out other causes:
- infectious: Herpes virus, WNV, EEE< WEE, Rabies
- NOninfectious: trauma, equine degenertive myeloencephalopathy, hepatic encephalopathy, hepatic encephlopathy, etc
- Serology: many hiorses have antibody titers, but no disease
- Clinical signs + rule out other causes + positive antibody titers = presumptive diagnosis
POstmortem diagnosisis is confirmatory:
- histopathology –> see protozoal schizont in CNS tissue
- Can confirm wih PCR
Discuss treatment for EPM
- ponazuril
- Diclazuril
- Anti inflammatory drugs, immune stimulants, and vitemin E are often given to these animals
- Relase is common, and some animals do not resoind to therapy
Prevetnion: no vaccine availavble; eliminate contact with opossum feces
Discuss Eimeria leuckarti
Eimeria Leuckarti: Coccidia
- The ONLY intestinal coccidia in horses —> NOT A PARASITE OF CONCERN
Discuss equine Piroplasmosis
Equinbe piroplasmosis: an apicomplexan protozoa
- Babesia cabelli
- Theileria equi
Reportable
For import, horses are tested serologically, and if positive:
1) Treat –> if becomes seronegative –> imported
2) Remain seropositive - | | –> no import to USA
A horse must test negative for both B cabelli and T equi in order to be imported into the United States
Discuss the lifecycle for Equine piroplasmosis
Life cycle: zoites in tick saliva infect horse RBCs after tick bite –> sexual replication (merozoites) in RBCs can infect othger new RBcs –> ingested by tick –> sexual replication
Tick vector:
- Mostly dermacentor sp –> 1 host tick
- Also Amyblomma spp –> 3 host tick
-
When consideing Euinne piroplasmosis; which spp belongs to each pic
Discuss the clinical signs of equine piroplasmosis
Clinical signs:
- high fever anorexia, depression, peripheral edema
- Hemolysis –> anemia, hemoglobinuria, icterus
Acute: rapid onset of clinical disease –> death
Chronic: recovery from acute –> carrier state for years; usually with no clinical signs; if **stressed ** or immunosupressed –> clinical disease
Discuss the diagnosis of equinepiroplasmosis
Diagnosis:
- Acute phase: A) Blood smears –> B. cabelli = 2 merozites while T. equi needs 4 merozites B) PCR
- Chronic phase –> difficult to diagnose by blood smears
- Serological tests for determining carrier status –> **ELISA test*
Prevention/Control: Specifically, we are going to control the ticks with permethrin, ivermectin, or cuomaphos
Discuss Trypanosoma equiperdum
Trypanosoma equiperdum: Flagellated Protozoa
- **“Dourine” ** - eradicated from the US; sexually transmiited in horses BUT ……… UPON IMPORT, horses get tested for it
