Habronema and Draschia spp.

HABRONEMA and DRASCHIA SPECIES

General

  • Spiruroids occurring in stomach:
    • Habronema microstoma - worldwide.
    • Draschia megastoma - tropical/sub-tropical climates.

Morphology

  • 1.0-2.5cm long, slender white worms, flat spiral twist to male tail.

Life-Cycle

  • Indirect LC, muscid fly intermediate hosts.
  • Adults under layer of mucous in stomach (Habronema) or in large nodule (Draschia).
  • Elongated embryonated eggs (50-60µm) passed in faeces.
  • L1 ingested by fly larvae - develop to L3 as fly matures.
  • L3 deposited on horse's lips as fly feeds - swallowed - mature to adult worms.
  • Prepatent period = 2months.
  • Larvae → "cutaneous habronemosis" or "summer sores":
    • larvae laid on skin wound → large granulomata
    • seasonal incidence
    • affected horses may be difficult to work.

Pathogenicity

  • Adult worms:
    • Habronema - mild gastritis (no mucosal invasion)
    • Draschia - tumour-like nodules may impair pyloric function.

Control

  • Regular anthelmintic treatment (adults - not required; larvae - ivermectin).
  • Cover or turn over dung heaps (to prevent access of flies to breeding sites or kill by composting).