As scientists learn more about the deadly parasite’s ability to move from host to host within turkey flocks, long-standing theories are being questioned and the door is opening to new preventative measures.
Histomonas meleagridis, the parasite behind histomoniasis – also known as blackhead blight – can devastate turkey flocks. There are currently no vaccines or treatments approved by the U.S. Food and Drug Administration to treat this bird.
Mortality in turkey flocks can reach up to 80%. Chickens are slightly less susceptible to this disease, but can still become infected. We don’t know about widespread mortality like in turkeys. ”
Daniel Graham, Assistant Professor of Poultry Science, University of Arkansas System College of Agriculture
Graham and Zicheng Do, an associate professor in Clemson University’s School of Biological Sciences, who conduct research through the Department of Agriculture’s Arkansas Agricultural Experiment Station, were recently awarded $3.2 million over five years by the U.S. Food and Drug Administration to support their research efforts. Awarded a grant. Developing insights into disease transmission and potentially discovering existing FDA-approved drugs to combat histiopathies.
FDA funding comes in the form of a collaborative partnership through the establishment of the Center for Animal and Veterinary Innovation. According to the FDA, these centers are intended to address urgent animal, human, or environmental health needs. The center in Arkansas is one of four the FDA announced in September.
Turkey accounted for $614 million in cash farm revenue in Arkansas in 2022, according to the latest Arkansas Agriculture Profile. According to the U.S. Department of Agriculture’s latest Turkey Breeding Report, Arkansas ranks third in the nation in turkey production. Minnesota and North Carolina rank first and second, respectively.
Evolving transmission theory
Two therapeutic classes of drugs, nitroimidazole and nitrofuran, have been previously used to reduce histiopathies in poultry. However, the FDA has banned their use in animals intended for human consumption due to concerns about carcinogenic residues. Nitalson, the last remaining drug approved to control tissue hyperplasia, was voluntarily removed from the market in 2015 due to other consumer health concerns. As a result, cases of histosynthesis have increased significantly, and the disease is now one of the biggest concerns for commercial turkey producers in the lower Midwest and Southeastern United States, Graham said. Ta.
Preliminary research by Graham and Dou, funded by the USDA, provided supporting evidence that led to the FDA grant. The researchers showed that H. meleagridis can survive in the lower pH environment of the turkey gastrointestinal tract and form cyst-like structures, a common survival strategy of protozoal pathogens to facilitate transmission. Graham said the development of inhibitors for this step could be crucial in controlling infectious diseases.
“Over the past 50 years, histomonopathies have been transmitted only outside the host by vectors, whether in the nematode Heterakis gallinarium or in the bodies of earthworms, which are parahosts of the nematode’s eggs. It was thought to be efficiently transmitted,” Graham said. “But in turkeys, that nematode doesn’t reproduce efficiently, so it doesn’t make sense that this is the primary way these protozoa are transmitted within a turkey flock.”
Paratenic hosts are transport hosts in the parasite’s life cycle where the parasite survives but does not reproduce.
Mr Graham said several routes of infection and transmission of H. meleagridis in commercial poultry flocks have been proposed. The current theory was that the parasite reaches the lower gastrointestinal tract by cloacal contact with parasite-containing feces or by cloacal contact with an infected host. However, it is unclear whether this type of contact in the absence of vectors such as nematodes is sufficient for rapid and sustained transmission in commercial turkey flocks. In birds, including male and female turkeys, the cloaca is the external connection to the digestive, urinary, and reproductive systems.
Because it is common for birds to ingest feces, and researchers have demonstrated that the parasites can survive in low-pH environments, Graham’s preliminary research suggests that transmission through contaminated feces or cecal feces may be difficult. This indicates that there is a possibility of It is the focus of an FDA-funded project, likely due to its cystic formation. The cyst acts like a kind of armor that protects the parasite as it makes its way to the target area, where it reverts to a form in which it can feed and multiply.
“We are at the limit of what is known about H. meleagridis,” Graham said. “Zhicheng, my collaborator at Clemson University, was eager to explore with me the uncharted territory related to cystoid formation, fecal-oral transmission, and even vaccine development. It has been a productive and exciting collaboration and I am really looking forward to what we have learned through this project. ”
Graham teaches courses in the Dale Bumpers College of Agriculture, Food and Life Sciences at the University of Arkansas and is affiliated with the Poultry Science Center for Excellence. The center is part of the Department of Agriculture and Bumper University and carries out three land-grant missions. We teach through Bumpers University, conduct research through experimental stations, and conduct extension activities through the agricultural sector’s Cooperative Extension Service.
For more information about the Department of Agriculture’s research, visit the Arkansas Agricultural Experiment Station website. Follow X at @ArkAgResearch, subscribe to the “Food, Farms & Forests” podcast and sign up for the monthly newsletter “Arkansas Agricultural Research Report.” For more information about the Department of Agriculture, visit uada.edu. Follow @AgInArk on X. For more information about Extension programs in Arkansas, contact your local Cooperative Extension Service agent or visit uaex.uada.edu.
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University of Arkansas System College of Agriculture
