Oxyuris equi

OXYURIS EQUI

General

• Pinworm; caecum; large intestine; rectum.
• Very common.

Morphology

• Female worms, <10cm long, white, long pointed tail.
• Male worms, <1cm (difficult to see).

Life-Cycle

• Adults in lumen of colon.
• Female migrates to anus, lay eggs on perianal hair (white streaks on hair; operculate eggs, 80-90µm, flattened on one side).
• Eggs fall to ground, L3 develops inside egg, ingested, L3 invades colonic mucosa, emerges as L4 matures.
• Prepatent period = 5months.

Pathogenicity

• Larvae (L4) - feed on colon mucosa, nip off epithelium, not true plug-feeders (erosions).
• Adults - non-pathogenic, feed on gut contents; but egg-laying activity of female worms irritant (pruritus ani), broken hair and bare patches over rump and tail head (seat itch).

Diagnosis

• Clinical signs.
• Egg streaks on perianal hair (sample using sellotape, place on slide).
• Faeces on gound (adult female worms).

Control

• Regular anthelmintic treatment.
• Sponge perianal region frequently when clinical signs present (scald sponge after).