epmfinal

epmfinal - EPM Equine Protozoal Myeloencephalitis `The...

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EPM – Equine Protozoal Myeloencephalitis ‘The Possum Disease’ By Abby Crane & Wendee McGuffee
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What is EPM? EPM is a neurological disease in horses caused by the protozoan Sarcocystis neurona . It is estimated that more than 50% of horses have been exposed, but less than 1% of these will go on to develop symptoms. Currently unknown how the horse’s immune system keeps the parasite at bay, but the suppression of the immune system increases the risk of developing the disease Injury Accidents Pregnancy
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Life Cycle of Sarcocystis neurona
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Progression NOT transferred horse to horse but spread by a definitive host – the opossum Intermediate hosts such as raccoons, skunks, armadillos and cats carry the protozoa as sarcocysts in their skeletal muscle Opossum eats the carcass and ingests the sarcocysts which develop into infective sporocysts that are deposited in the feces Horses become infected by eating contaminated feed or drinking contaminated water
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Progression (cont) Once ingested by the horse, the sporocyst goes through a maturation stage and becomes a merozoite Believed to occur in the endothelial cells of the digestive tract Merozoite gains access to the CNS by crossing the blood/brain barrier Believed to occur by infecting WBC but mechanism is currently unknown Once in nervous tissue, merozoites replicate to form a schizont (pouch of multiple merozoites)
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Progression (cont) Schizont eventually ruptures Destroys the host cell Damages nearby nerve tissue Releases more merozoites to infect other cells The resulting tissue death eventually causes the neural
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This note was uploaded on 01/31/2012 for the course BIOL 101 taught by Professor What during the Spring '11 term at TUFS.

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epmfinal - EPM Equine Protozoal Myeloencephalitis `The...

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