Parascaris equorum

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PARASCARIS EQUORUM

Parascaris equorum - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona
Parascaris equorum - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona
Parascaris equorum - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona
Parascaris equorum - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona

General

  • Ascarid, small intestine.
  • Mostly in young horses, especially foals <6months old.

Morphology

  • Stout worms, up to 50cm long.
  • Three large lips around mouth.

Life-Cycle

  • Direct.
  • Infection - ingestion of embryonated egg (L2).
  • Egg (100µm diameter, brown, thick pitted shell).
  • Larvae → hepatotracheal migration (liver → heart → lungs → intestine, 3weeks).
  • Prepatent period = 10-12weeks.

Pathogenicity

  • Larvae - eosinophilic tracts and haemorrhages in liver and lungs. Clinically, latter may lead to cough and nasal discharge.
  • Adult worms - may cause unthriftiness, weight loss; impaction and intestinal perforation rarely.

Epidemiology

High Fecundity of Female Parascaris:

  • Infected foal may pass millions of eggs per day.

Resistance of Eggs in Environment:

  • Thick, pitted shell ensures prolonged survival (>1year).
  • Sticky outer shell aids passive spread.

Susceptible Animals:

  • Foals (<4months) - transmission from one year's foals to the next, infection normally occurring during the first month of life.
  • Adult horses - few worms only (carriers?).

Control

  • Regular anthelmintic treatment.
  • Remove faeces from paddocks - collect every 2weeks (takes 2weeks to reach L2 stage).