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Cochlosomiasis ( Cochlosoma anatis ) in Turkeys and Ducks

By

Robert B. Beckstead

, PhD, North Carolina State University

Last full review/revision Sep 2019 | Content last modified Sep 2019
Topic Resources

Cochlosoma anatis is a flagellated protozoan that infects ducks, turkeys, geese, and wild birds. C anatis can cause limited pathology in the gut of ducks and turkeys, leading to diarrhea, although the direct pathology is still debated. Microscopic evaluation of intestinal mucosal scrapings can be used to determine infection. There is no treatment or vaccine for this protozoan.

Etiology

By light microscopy, Cochlosoma anatis is 6–12 micrometers (mcm) long and 4–7 mcm wide, with a characteristic adhesive disc on the anteroventral surface of its pyriform body. It moves in a jerking motion. This protozoan has a single nucleus and uses flagella for movement. Lateral transmission has been observed with turkeys, but direct contact of the birds was necessary for infection. PCR has detected C anatis on house flies, but no studies have demonstrated them as carrying live trophozoites.

Clinical Findings and Lesions

There is a debate on the pathogenicity of C anatis in avian species. The exact role of this parasite is unknown, because coinfection of viruses, bacteria and other protozoans with C anatis has led to gastrointestinal distress whereas infection with this protozoan alone does not always lead to clinical signs. Scanning electron microscopy has shown C anatis attaching to intestinal mucosa; however, no visual changes in the intestines have been observed under light microscopy with the protozoan present.

Diagnosis

Light microscopy and PCR are used to identify Cochlosoma anatis in intestinal scrapings and feces. Analysis of samples within two minutes of collection is recommended for proper identification because C anatis becomes immobile when cooled.

Prevention and Treatment

Wild birds, small rodents, and multi-aged flocks have been identified as carriers of C anatis. Proper biosecurity prevents the entry of this parasite to poultry flocks. Disinfection of housing facilities after an outbreak is necessary to prevent contamination of future flocks. Nitroimidazole and nitarsone have been proven as successful treatments for C anatis, but unfortunately these products are not approved in commercial poultry.

Key Points

  • C anatis is a flagellated protozoan that has debatable pathogenicity in avian species.

  • Intestinal scrapings and fecal material can be used for identification.

  • No treatments are currently available for cochlosomiasis.

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