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14 Cards in this Set
- Front
- Back
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Describe Order Oxyurida.
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Parasites of large intestine (pinworms) - host specific
Adult females (+/- males) have long, tapering tail Have direct life cycles: infection usually by ingesting larvated egg; often occurs via grooming activities |
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What are the superfamilies of Oxyurida?
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1. Oxyuris equi - horses
2. Syphacia ssp - rodents 3. Aspicularis - rodents 4. Enterobius vermicularis - human |
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Describe the superfamily Oxyuroidea.
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Typical egg: elongated and flattened on one side; thick smooth shell; many have an operculum at one end
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Describe Oxyuris equi.
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1. Common equine pinworm: ubiquitous in horses
2. Adult worms in weanlings, yearlings and adolescent horses - rarely present in adult horses 3. Immature worms occur in horses of all ages Morphology: creamy or off white color (don't suck blood); adult males (1/2 inch; no bursa); adult females ~ 2 to 6 in - tail of young females is short and pointed while tail of older females up to 3X length of main body |
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What is the life cycle of Oxyuris equi?
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Adults in cecum, colon and rectum: fertilized females exit host via anus; glues egg masses to perineum and dies
L3 develops inside egg in ~4-5 days; eggs fall off, contaminate environment, ingested L3 hatch in SI --> penetrate mucosa of ventral colon and cecum --> develop to L4 in 4-10 days, return to lumen and develop to adults |
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What are the clinical signs of Oxyuris equi?
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L4 on gut mucosa in large numbers --> inflammation, abdominal discomfort
Adults cause few, if any, signs Presence of eggs on perineum causes clinical signs: eggs are covered with highly irritated sticky substance; causes intense anal pruritus |
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How can you diagnose Oxyuris equi?
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Clinical signs and history suggestive
Fecal exam: might find eggs by fecal flotation; adult worms sometimes passed in feces Preferred method: detect eggs around anus with scotch tape |
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How can you treat and control Oxyuris equi?
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1. Wash perineum to remove eggs
2. Clean stalls and destroy bedding 3. Anthelmintic |
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What are the rodent pinworms?
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1. Mice - Syphacia obvelata: cecum
2. Rat - Syphacia muris: cecum; Aspicularis - proximal colon 3. Hamsters and gerbils: susceptible to all 3 pinworm species; infections usually asymptomatic |
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What is the life cycle of Syphacia spp?
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Female crawls out of anus --> deposits eggs on perianal area and dies --> infection by ingestion of eggs --> eggs very resistant and easily aerosolized (scotch tape method)
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What are the clinical signs of rodent pinworms?
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Usually asymptomatic
Heavy infection --> clinical signs: anal pruritus - can lead to self mutilation at tail head; rectal prolapse; sticky stools |
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How do you diagnose Syphacia spp?
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Syphacia obvelata: banana shaped and elongated with pointed ends with one flat side and one convex
Syphacia muris: football-shaped with blunt to rounded ends |
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Describe Aspicularis tetraptera.
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Adults lay eggs in lower colon
Eggs detected by fecal flotation (NOT scotch tape method) - ellipsoidal and not flat on one side; shell thinner than Syphacia spp |
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Describe Enterobius vermicularis.
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Pinworm of humans and other apes: common in young children especially in group housing situations
Does NOT occur in dogs or cats! NONE of animal pinworms are zoonotic Females lay eggs in early morning - collect with scotch tape |
