Cochlosoma anatis: An Emerging Health Threat in Turkeys
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Co-author: Justin Lowery
What is protozoal enteritis?
Protozoal enteritis in turkeys is a small intestine disease relating to infection with flagellated protozoa such as Cochlosoma, Tetratrichomonas, and Hexamita (Clark and Froebel, 2020). Effects of protozoal enteritis are mostly observed in younger turkeys. Diarrhea, lethargy, and decreased weight gain are the most common symptoms associated with protozoal enteritis. Furthermore, secondary infections may occur from disruptions of gut homeostasis leading to bacterial overgrowth or invasion of the intestine by opportunistic pathogens, potentially leading to more severe disease.
What is Cochlosoma anatis?
Cochlosoma anatis is a flagellated protozoan parasite of the intestine in ducks, geese, other wild birds, and turkeys. The disease caused by infection with C. anatis is known as cochlosomiasis and results in hallmark symptoms of protozoal enteritis as described above. Additionally, lethargy in turkeys from cochlosomiasis often makes the birds appear dirty with ruffled feathers. Concern for this parasite amongst the commercial turkey industry in the United States has risen with an increase in farm outbreak occurrence with a lack of available treatment.
Diagnosis of Cochlosoma anatis
Diagnosis of infection with C. anatis in turkeys commonly occurs after observing decreased weight gain and watery diarrhea by some birds in the flock. Diagnostic techniques are currently limited to microscopic examination from an intestinal mucosal scrape or fresh fecal sample acquired from a bird presenting with symptoms consistent with enteritis. When viewed microscopically, C. anatis moves in a jerky, spiraling motion.
Survival of C. anatis in the environment outside the intestine is fragile, with most parasites dying when their conditions become drier and/or colder. Multiple attempts have been made to preserve living C. anatis in an observable living state, however, all attempts have failed. No in vitro culture methods are available for C. anatis cultivation (Lindsay et al., 1999; Evans et al., 2006).
Where is cochlosomiasis most likely to occur and when?
Infections with C. anatis have been largely limited to the southeastern United States, with additional outbreaks occurring in turkey production facilities in Missouri and Arkansas. Industry testimonies and epidemiological observations suggest that C. anatis is most likely to enter commercial turkey flocks beginning in the mid- to late- summer months and continue throughout the fall into the beginning winter months when infection occurrence begins to wane. No confirmed or suspected vectors are known currently.
How do we minimize the risk of cochlosomiasis outbreaks?
Strict biosecurity measures are best suited to prevent the introduction of C. anatis to any turkey flock. Because C. anatis does not survive well outside the host, vectors likely exist that facilitate the introduction of the parasite to turkey flocks. Therefore, biosecurity targeting pest insects, rodents, and other wild animals is advised for the best protection of the turkey flock.
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Research has shown that infection with C. anatis earlier in life may lead to more severe disease, causing increased disease severity and mortality (Lowery, 2023). Therefore, slowing the spread of infection is advised to allow the susceptible birds the best chance to gain weight and grow older before becoming infected with the parasite. Since C. anatis does not survive well in dry environments, turning over the litter and maintaining a drier house may benefit in the reduction of the rate of spread of the parasite throughout the flock.
References
Clark, S., and L. Froebel. 2020. 2020 Turkey Industry Annual Report – Current Health and Industry Issues Facing the US Turkey Industry. Huvepharma.
Evans, N. P., R. D. Evans, S. Fitz-Coy, F. W. Pierson, J. L. Robertson, and D. S. Lindsay. 2006. Identification of New Morphological and Life-Cycle Stages of Cochlosoma anatis and Experimental Transmission Using Pseudocyst. avdi 50:22–27.
Lindsay, D. S., C. T. Larsen, A. M. Zajac, and F. W. Pierson. 1999. Experimental Cochlosoma anatis infections in poultry. Veterinary Parasitology 81:21–27.
Lowery. 2023. Evaluating the Effects of Cochlosoma anatis Infection on Turkey Poult Gut Health and Performance. Available at https://repository.lib.ncsu.edu/handle/1840.20/41234.
