Habronema muscae

Habronema
Scientific classification
Kingdom: Animalia
Phylum: Nematoda
Class: Secernentea
Order: Spirurida
Family: Habronematidae
Genus: Habronema
Species: Habronema muscae

Habronema muscae is an internal stomach parasite that is most commonly found in horses. It is in genus Habronema.

Life cycle

Eggs

The parasitic adult female worms lay eggs within the horse's stomach. The eggs are later excreted through the feces. The eggs hatch out within the faeces producing first stage larvae.[1]

Larvae

After the eggs have hatched in the faeces, the larvae are ingested by the maggots of various flies that lay their eggs in the faeces (such as Stomoxys (the stable fly) or Musca (the house fly). The nematode larvae develop within the maggot for about one week (depending upon ambient temperature), as the maggots mature into the imago (adult) fly. The infective larvae migrate to the mouthparts of the fly, where they are passed on to the horse when they feed around the horse’s moist areas such as wounds, nostrils, lips, and eyes. If the larvae are deposited into open wounds, or broken skin they can cause intense granulomatous reactions, producing an ulcerated irritation called "summer sores". They may also invade the eye and the eye membrane causing a persistent conjunctivitis. If the larvae find their way up through the nose they can migrate into the lungs and cause tiny abscesses around where they embed in the lung tissue.[1]

Adults

When the larvae are licked and swallowed by the horse during grooming they travel to the stomach and embed themselves into the glandular part of the stomach close to the margo plicatus. A thick mucus is excreted by the stomach lining. The larvae mature into adults and females produce eggs to complete the life cycle.[1] Larvae that invade skin or eye tissue do not develop into adults.

Morphology: Adult has two lateral lips, dorsal and ventral lips may also be present. Buccal capsule cylindrical, chitinous. Oesophagous is divided into two parts, a short anterior muscular and long posterior glandular portion, intestine simple without any diverticula. Male: spicules unequal, gubernaculum present and bears 4 pairs of preanal, 1 pair adanal and 2 pairs of postanal pedunculated papillae, 3 pairs of sessile papillae also present, tail spirally twisted.[2]

Treatment

Skin lesions probably due to Habronema
Horse recovering from skin lesions probably due to Habronema, after treatment with ivermectin

An parasiticide that is effective against Habronema is ivermectin.

Control of the fly population (house flies, horse fly, and face fly) can decrease the likelihood of habronema infection.

References

  1. 1 2 3 Hewitt, C. Gordon (2011). The House-Fly: Musca Domestica Linn: Its Structure, Habits, Development, Relation to Disease and Control. Cambridge University Press. pp. 181–184. ISBN 978-0-521-23299-9.
  2. ↑ A colour Atlas of Equine Parasites D.E. Jacobs 1986 Balliere Tindall London
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