Epomidiostomum		Contents		Rev 05/29/2025
Guiinea Worms		Classification		Biology and Ecology
		Morphology and Anatomy		Life Cycle
Return to Epomidiostomum Menu				Ecosystem Functions and Services
		Distribution		Management
Return to Trichostrongylidae Menu		Feeding		References
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Classification:

Chromadorea

Chromadoria

Rhabditida

  Rhabditina

   Trichostronglyloidea

    Trichostrongylidae

Epomidiostomatinae (or Amidostomatinae)

Epomidiostomum Skrjabin, 1915

Type species of the genus: Epomidiostomum

Synonyms:

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Morphology and Anatomy:

ref:

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Distribution:

Gizzard worms are some of the most commonly found species of helminths infecting waterfowl.

Reported from wild Canada Geese (Branta canadensis), Snow Geese (Chen caerulescens), Ross's Geese (Chen rossii), Northern Pintail (Anas acuta), and Green-winged Teal (Anas carolinensis) in California.

Amidostomum spatulatum was reported from Canada Geese  which were also infected with Epomidiostomum crami.

The nematodes are widely distributed in species of migratory waterfowl.

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Economic Importance:

Gizzard worms cause ventricular nematodiasis and amidostomiasis or epomidiostomiasis

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Hosts:

Gizzard worms of the genera Amidostomum and Epomidiostomum are commonly foumd as parasites of waterfowl of the family Anatidae (Fedynich and Thomas, 2008)

Pathology reported in wild geese, ducks and swans.

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Feeding:

Food Sources and Feeding strategies for the genus Epomidiostomum

Intestinal parasite of waterfowl

Adults inhabit the chitinous lining of the gizzard (ventriculus) where they feed on blood.

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Life Cycle:

The life cycle is direct, no intermediate hosts involved.

•  Partially developed eggs are released from the adult female worm into the gastric lumen of the infected host and excreted into the environment with the feces.
• Survivability of eggs and larvae in the environment varies; they require moist conditions for survival (Anderson, 2000) which ezplains the prevalence of infections in waterfowl.
• Low temperatures inhibit larval development within the egg and prevent hatching, while embryo development to third-stage larvae are increased at warmer temperatures..
• After a short free-living stage of about 4-9 days, third-stage larvae become infective to susceptible hosts and can remain viable up to 20 days under suitable environmental conditions (Leiby and Olsen 1965).
• Susceptible hosts become infected when they ingest the infective third-stage larvae during feeding or drinking. Additionally, larvae of A. anseris can penetrate the skin and migrate to the lungs and trachea prior to invading the gizzard lining (Anderson 2000).
• Larvae penetrate the thinner portions of the gizzard epithelium at the junction of the gizzard and proventriculus after ingestion.
•  Development to the fourth stage requires 2-4 days (Leiby and Olsen 1965), and adults dmature in 12-25 days

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Damage:

High levels of infection of gizzard worms (ventricular nematodiasis) causes damage to the koilin lining and associated muscle of the gizzard and leads to gizzard dysfunction. That results in emaciation, weakness, and poor growth rates of juveniles. Debilitated hosts may be more susceptible to predation or infection by other pathogens. Migratory birds in poor condition from ventricular nematodiasis may be unable to cope with the energy costs of migration and the  increased competition for limited food resources during winter (Fedynich and Thomas, 2008)

There is potential for transmission of gizzard worms between domestic and wild birds within the Anatidae. Species reported in domestic ducks and geese include A. acutum, A. anseris, and E. uncinatum (McDonald 1969). Consequently, unenclosed zoological gardens, open-air commercial farms, and backyard flocks may be at risk from wild anatids infected with these species of gizzard nematodes

There is no evidence that species of Amidostomum and Epomidiostomum present human health concerns. However, for human consumption, gizzards should be thoroughly cooked or discarded if nematode-damaged tissues are apparent because of possible secondary bacterial infections  (Fedynich and Thomas, 2008)

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Management:

Avoidance:

• raising young and old birds separately to prevent exposure of uninfected young individuals to infected older individuals

•  maintaining good sanitation practices (Levine 1968).

Anthemintics:

•  prevent access of wild anatids to captive or domesticated flocks, particularly if anthelmintics are being used, because reinfection can rapidly occur following treatment.

• anthelmintics are effective on infected captive wild anatids and commercial flocks.

• specific anthelmintics reported by various sources to kill Amidostomum anseris include flubendazole, mebendazole, cintrin, cambendazole, pyrantel, and combibations of neguvon, atropine sulfate, and piperazine sulfate (Fedynich and Thomas, 2008)

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References:

Anderson, R. C. 2000. Nematode Parasites of Vertebrates: Their Development and Transmission, 2nd ed. CABI Publishing, New York.

Fedynich, A.M.  and Thomas, N.J., 2008. Amidostomum and Epomidiostomum,  Chapter 20 (pp355-375) in Atkinson, C.T., Thomas, N.J., Hunter, D.B. Parsitic Diseases of Wild Birds. Blackwell Publishing.

Leiby, P. D., and O. W. Olsen. 1965. Life history studies on nematodes of the genera Amidostomum (Strongyloidea) and Epomidiostomum (Trichostrongyloidea) occurring in the gizzards of waterfowl. Proceedings of the Helminthological Society of Washington 32:32-49.

Levine, N. D. 1968. Nematode Parasites of Domestic Animals and of Man. Burgess Publishing Company, Minneapolis, MN

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