Aquatic Parasite Observatory

Epomidiostomum unicatum

    • Species Name: Epomidiostomum unicatum (Lundhal, 1848)
    • Synonyms: Strongylus uncinatus (Lundhal, 1848); Epomidiostomum anatinum (Skrjabin, 1916)
    • Taxonomy: (Lundahl, 1848) Animalia, Nematoda, Secernentea, Strongylida, Amidostomatidae, Epomidiostomum unicatum
    • Description: "The body is slender, attenuated anteriorly, the striations being more developed in the neck region... The head is distinctly set off from the body proper. It shows a special cuticular expansion forming two lateral plates, and one dorsal, and one ventral plate. The lateral plates are not so conspicuous; both the dorsal and the ventral plate, which have the shape of a spherical triangle, are more prominent. The front surface of the head is supplied dorsally as well as ventrally with a pair of flaplike appendices, bending backward in a subdorsal and subventral direciton, respectively... The lateral papillae or amphids are exceedingly well developed and prominent. On both sides of each lateral amphid there is a glistening spinelike formation, which, as can be seen by a lateral-front-end view, is a kind of support of outstanding amphid... The mouth opening is quarded by four toothlike formations arranged in the shape of a rectangle...The mouth cavity is funnel shaped leading to an elongated club-shaped esophagus" (Wetzel, 1931).
    • Life Cycle: Epomidiostomum sp. have a direct life cycle in which the infective parasite larvae invade a single host animal for development to reproductive maturity (Fig. 32.1). Embryonated eggs are passed in the feces of an in-fected host bird. First-stage larvae hatch from the eggs into the surrounding environment in about 24–72 hours, depending on the ambient temperature. These larvae molt twice after they hatch, and the time between molts also depends on the temperature. Larvae are quite resilient, surviving low temperatures and even freezing; they do not, however, survive drying. After a bird ingests the larvae, most commonly when a bird feeds or drinks, they enter the gizzard and burrow into its surface lining where they molt again before they become adult worms. Adult worms become sexually mature in about 10–15 days after the final molt, and females shed eggs within 15–20 days. The development from egg to adulthood may take as few as 20 days or as many as 35 days depending on environmental conditions. Once a bird is infected, it can harbor gizzard worms for several years” (Friend and Franson, 1999).
    • Sources: Wetzel, R. 1931. Description of a new species of Amidostomine worm of the genus Epiomidiostomum from the gizzard of Anserine birds. Proceedings U.S. National Museum, Vol. 78, Art. 21, No. 2864, p. 1-10.
    • Friend, M. and Franson J.C. 1999. Field Manual of Wildlife Disease — General Field Procedures and Diseases of Birds. US dept. of the interior. Accessed online at on Jan 20, 2016. Chapter 32.
    • APO Parasite Records: (by Life Cycle)

  • University of Colorado Boulder