Histomonas meleagridis infections in turkeys in the USA: A century of progress, resurgence, and tribute to its early investigators Theobald Smith, Ernst Tyzzer, and Everett Lund

Authors: Dubey, Jitender; Parker, Carolyn; D. GRAHAM, DANIELLE - University Of Arkansas; HARGIS, BILLY - University Of Arkansas; Jenkins, Mark

Submitted to: Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/15/2024
Publication Date: 7/10/2024
Citation: Dubey, J.P., Parker, C.C., D. Graham, D., Hargis, B., Jenkins, M.C. 2024. Histomonas meleagridis infections in turkeys in the USA: A century of progress, resurgence, and tribute to its early investigators Theobald Smith, Ernst Tyzzer, and Everett Lund. Journal of Parasitology. 110(4):263-275. https://doi.org/10.1645/24-8.
DOI: https://doi.org/10.1645/24-8

Interpretive Summary: Turkeys and chickens are important for the economy of the United States. Histomoniasis, a disease caused by a single celled parasite, Histomonas meleagridis, threatens the turkey industry now reemerging because the drugs used to control it are now prohibited by Food and Drug Administration because of food safety concerns. Responding to the needs of turkey growers, a new CRIS project has been recently funded by US Congress at the Animal Parasitic Diseases Laboratory in collaboration with scientists from Arkansas University. Here, the authors review history and future research on histomoniasis. This information will be useful to veterinarians, poultry scientists, and biologists.

Technical Abstract: Histomoniasis, caused by the protozoan, Histomonas meleagridis, is an economically important disease of turkeys, and it also affects several other species of domesticated and wild Galliformes, including chickens. Under natural conditions, the parasite is transmitted through eggs of a nematode, Heterakis gallinarum, that shares its hosts with Histomonas meleagridis. The protozoan infects tissues of both male and female Heterakis gallinarum, and eventually is carried within the worm egg. Histomonas meleagridis more readily infects and develops in chickens, and the proximity of chicken farms is a major risk factor for outbreaks in turkeys. Chemoprophylaxis and husbandry techniques have controlled Hi. meleagridis in turkeys very successfully, but histomoniasis has recently reemerged disease in turkeys, because anti-histomonal drugs are no longer permitted by United States Food and Drug Administration because of the concerns for residual toxins in meat. Horizontal transmission of the protozoan in the absence of worm eggs remains a mystery because the flagellate trophozoite excreted in feces of turkeys is not viable for any length of time. A proposed resistant stage of the protozoan has not yet been conclusively demonstrated. Here, we review the discovery of the protozoan and the current status of the disease and its control.