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Scientific classification
Kingdom: Animalia
Phylum: Nematoda
Class: Secernentea
Subclass: Rhabditia
Order: Ascaridida
Family: Heterakidae
Genus: Heterakis
Schrank, 1790
~10 species

Heterakis is a genus of parasitic nematodes. Members of the genus are minute roundworms (pinworms), hardly 1 cm long, infecting different species of gallinaceous birds, including chickens, turkeys, ducks, geese, grouse, guineafowl, partridges, pheasants, and quail. About 10 species are placed in the genus, but classification is often ambiguous due to their close resemblance, and a number of synonyms have arisen. H. gallinarum Schrank, 1788; H. isolonche von Linstow, 1906; and H. dispar Schrank, 1870 are the best understood species in terms of prevalence, pathogenicity, and biology. They inhabit the lumen of the cecum of the host.[1]

The nematodes are whitish in colour, cylindrical, and with fine longitudinal striations throughout the body. The body covering is a proteinaceous layer named cuticle. The anterior end is the mouth with distinct lips, and the anus opens towards the posterior. They are diecious with marked sexual dimorphism. Males are shorter and smaller, with straight blunt tails, while females are bigger and longer, with curved tails. They all exhibit direct lifecycles. They cause nodular typhlitis, diarrhoea, emaciation, and death.[2] H. gallinarum is the most well-known species, and is most important as it transmits the protozoan parasite, Histomonas meleagridis in birds.[3][4]


  1. ^ Permin A & Hansen JW (1998). The Epidemiology, Diagnosis and Control of Poultry Parasites. Food and Agriculture Organization of the United Nations, Rome, Italy, pp. 29-30. ISBN 92-5-104215-2
  2. ^ Kaufmann, J (1996). Parasitic Infections of Domestic Animals: A Diagnostic Manual. Birkhäuser Verlag AG, Basel, Switzerland, p. 423. ISBN 3-7643-5115-2
  3. ^ Lund, EE; Chute, AM; Wilkins, GC (1975). "The wild turkey as a host for Heterakis gallinarum and Histomonas meleagridis". Journal of Wildlife Diseases. 11 (3): 376–81. PMID 1171270. doi:10.7589/0090-3558-11.3.376. Archived from the original on 2009-04-18. 
  4. ^ Brener, B; Tortelly, R; Menezes, RC; Muniz-Pereira, LC; Pinto, RM (2006). "Prevalence and pathology of the nematode Heterakis gallinarum, the trematode Paratanaisia bragai, and the protozoan Histomonas meleagridis in the turkey, Meleagris gallopavo" (PDF). Memorias do Instituto Oswaldo Cruz. 101 (6): 677–81. PMID 17072483. doi:10.1590/s0074-02762006000600017. Archived from the original (PDF) on 2011-07-20. 

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