Heterakis		Contents		Rev: 10/16/2026
		Classification		Biology and Ecology
		Morphology and Anatomy		Life Cycle
Return to Heterakis Menu				Ecosystem Functions and Services
		Distribution		Management
Return to Heterakidae Menu		Feeding		References
		Go to Nemaplex Main Menu		Go to Dictionary of Terminology

Classification:

Chromadorea
Chromadoria

           Rhabditida 

                        Spirurina

                          Heterakoidea

                   Heterakidae

 

            Heterakis Seurat, 1915

Parasites of gastrointestinal tracts of birds.

    Synonyms:
      

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Morphology and Anatomy:

With general characteristics of the family Heterakidae.

Specifically:

• Cuticle transversely striated
• Stoma surrounded by three lips, each lip having two papillae;
• Lateral flanges or alae present or absent
• Esophagus in 3 parts: pharynx that is narrow anteriorly, broadens posteriorly, and ends with a well-developed posterior bulb containing a valvular apparatus

Ref: Fedynich, 2008

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Distribution:

At least one species of Heterakis has been reported from every continent except Antarctica (Fedynich, 2008).

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Feeding:

Food Sources and Feeding strategies for the genus Heterakis

Parasites of gastrointestinal tracts of birds.

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Biology and Ecology:

Lethargy of birds with heavy infections. Nonspecific signs of heterakiasis in captive pheasants include emaciation, weakness, diarrhea, dyspnea, and terminal gasping. Greater susceptibility to predation

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Life Cycle:

Nematodes with direct lifecycles, no intermeduiate hosts, and are primarily parasites of the intestinal tract.

• Gravid females release unembryonated eggs into the intestinal tract of the host and the eggs are subsequently voided with the feces.
• Embryonation occurs after eggs exit the host, and transmission is complete when a susceptible host ingests the embryonated egg..
• Embryonation is dependent on environmental conditions: optimal development of the eggs of H. gallinarumi occurs at 18-33 C and eggs take 7 to 17 days to hatch into infective juveniles (Anderson 2000).

Heterakis gallinarum larvae may be transported  by earthworm paratenic hosts. Eggs hatch after they are ingested by the earthworm and transmission occurs when the earthworm is eaten by the definitive host (Fedynich (2008).

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Ecosystem Functions and Services:

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Management:

Keep domestic birds away from wild birds to reduce probability of infection.

Anthelmintics have been used extensively on captive flocks of chickens and turkeys and they should be effective for wild or captive wild species. The U.S. Food and
Drug Administration approves specific anthelmintics that are used in birds intended for human consumption (i.e., eggs or meat) and has authorized fenbendazole,
phenothiazine, and hygromycin B for poultry (Fedynich, 2008), Check advisory and regulatory  services for current recommendations.

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References:

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

Cruthers, L.R., Reinemeyer, C.R., Yazwinski, T.A., Marchiondo, A.A. 2020. Nematoda, Ascaridida. Chapter 2 in Marchiondo, Cruthers and Fourie (eds) Parasiticide Screening Vol 2. Academic Press

Fedynich, A.M. 2008. Heterakis and Ascaridia. Chapter 23 in Atkinson, C.T., Thomas, N.J. and Hunter, D.B. (eds) Parasitic Diseases of Wild Birds.  John Wiley & Sons, Inc. ISBN: 978-0-813-82081-1

Jimenez-Ruiz, F.A. 2024. Heterakoidea (Superfamily): Cosmopolitan Gut-Dwelling Parasites of Tetrapods. Chapter 51 in S. L. Gardner and S. A. Gardner, eds. Concepts in Animal Parasitology. Zea Books, Lincoln, Nebraska, United States. doi:10.32873/unl.dc.ciap053

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Revised by Howard Ferris: October 16, 2026.