Habronema is a genus of nematodes in the order Spirurida. Species include: Habronema clarki – rodent parasite; Habronema incertum – bird parasite. equids: Habronema muscae, Habronema majus, Draschia megastoma and Trichostrongylus axei. Habronema spp and Draschia megastoma belong to the. Aust Vet J. Jan;45(1) A survey of habronema spp and the identification of third-stage larvae of Habronema megastoma and Habronema muscae in.

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Habronema – Wikipedia

Habronema is a genus of parasitic roundworms that affects horses, donkeys and other equids worldwide. Othe species of the same family affect also birds, amphibians and reptiles. They all occur worldwide, but prevalence and incidence vary a lot depending on the region and the climatic conditions. These worms do not affect cattle, sheep, goats, pigs, dogs or cats.

The disease caused by Habronema worms is called habronemiasis or habronemosis. Predilection site of adult Habronema worms is the stomach. Larvae can be found in skin, the eyes, genitalia and even in the lungs. Adult Habronema spp are medium-sized worms, up to 3. Habronema muscae has a yellow to orange color, while other species are whitish. The worms have a tubular digestive system with two openings, the mouth and the anus.

The mouth of Habronema worms is provided with lip-like structures and has a cylindrical vestibulum. They also have a nervous system but no excretory organs and no circulatory systemi. The female ovaries are large and the uteri end in an opening called the vulva that opens near the habrondma of the body.

Males have caudal wings alae and a copulatory bursa with two unequal spicules for attaching to the female during copulation. Morphology of the spicules is species-specific, important for species determination. Each egg contains an already formed larva. Habronema microstoma and Draschia megastoma are viviparous, i. Adult female worms lay eggs or habrone,a L1- larvae in the stomach of the horses that are passed with the feces.

These larvae are ingested by fly maggots that develop in the horse manure. These larvae complete development to infective L3 larvae inside the maggots within about 2 weeks.

Once the fly maggots complete their development to adult flies, the infective L3 larvae migrate to the mouth of the ahbronema from where they are deposited on the final host horses, donkeys, etc.


They are often deposited on humid parts of the host’s body eyes, nose, lips, genitalia, open wounds, etc. Once on the final host, L3 larvae are swallowed and get into the stomach where they habronea development to adult worms within about 2 months. Infective L3-larvae can also infect the hosts if they swallow flies e.

Larvae that do not reach the stomach but remain in the tissues e. Since occurrence of the flies is seasonal and depends strongly on climatic conditions temperature, humidity, etc. Habrnoema prepatent period time between infection and first eggs shed is about two months, suggesting that more than one generation can follow during a normal season in regions with a warm and humid climate.

Adult worms in the stomach so-called gastric habronemiasis of horses are usually not very pathogenic. They do not penetrate through or into the stomach wall as other parasitic worms do e.

Large and Small Strongylesbut remain in the lumen, mainly in the mucus surrounding the wall, and do not feed primarily on blood but on other digestive or body fluids. In case of massive infections they can cause gastritis, colic, and other digestive disorders that can result in weight loss.

Draschia megastoma can causes tumor-like swellings in the stomach wall that can burst and cause fatal peritonitis, but this is rather unusual.

Infective L3-larvae that are deposited on the eyes cause so-called ocular, ophthalmic or conjunctival habronemiasis that can cause inflammation of the eye envelopes conjunctivitis and the eyelids. Infective L3-larvae deposited on skin wounds produce so-called skin or cutaneous habronemiasis, also known as “summer sores”. They produce granulomatous skin reactions erosions, swellings, etc. Such infected wounds are difficult to heal, can become infected with secondary bacteria and may attract other fly species that can cause myiasis e.

Occasionally, infected L3-larvae deposited on the nostrils can migrate into the lungs of the host and cause so-called pulmonary habronemiasis. Small, hazelnut-like nodules can appear around the bronchi. Affected horses may show chronic cough, difficult breathing and reduced performance. Both young and adult horses are affected, suggesting that affected animals do not develop significant levels of immunity to these worms.

Diagnosis of gastric infections is difficult because the small eggs or L1-larvae passed in the feces are easily missed in fecal examinations. Non-healing skin wounds showing reddish to brownish color and containing rice-grain-like calcified material are typical for skin habronemiasis.


Larvae may be found in scrappings of such wounds. A key measure to reduce the risk of infection is adequate manure management to break the life cycle of the worms, both outdoors and indoors, since flies can develop in horse droppings both on pasture as well as inside stables and barns. Regular manure removal ideally daily, at least weekly in stables and barns can significantly reduce the fly populations, provided that manure heaps elsewhere are adequately handled for preventing fly development keep it dry, promote maggot predators, etc.

If possible manure should also be removed from pastures, or at least the fecal balls should be broken to accelerate drying and make it less suitable for maggot development. For additional non-chemical control measures of flies read the specific article on houseflies and stable flies in this site.

Draschia megastoma/Habronema spp. (1) Flashcards Preview

So far no true vaccine is available against Habronema worms of horses. To learn more about vaccines against parasites of livestock and pets c lick here. Very little is known regarding the immune response of horses to Habronema infections and whether significant levels of immunity can be acquired after repeated exposure. Biological control of Habronema worms i. However, under certain circumstances manure-breeding flies can be successfully controlled using their natural enemies: You may be interested in an article in this site on medicinal plants against external and internal parasites.

Two major classes of anthelmintics are effective against Habronema worms and larvae in the gut: In some countries feed-through larvicides mainly with cyromazine are approved for use on horses that can contribute to reduce the fly populations in animal premises. Since habronemiasis is caused by an allergic reaction of the host tissues to the worms, besides administration of an anthelmintic additional medication may be considered e.

So far there are no reports on resistance of Habronema worms to anthelmintics. Learn more about parasite resistance and how it develops. Ask your veterinary doctor! If available, follow more specific national or regional recommendations for Habronema control. Control of Flies Biol. Control of Ticks Biol.

Biology, prevention and control. Details Written by P. Also in this site: