Until just a couple of years ago, histomonas (blackhead) in turkeys was fairly easy to control, but then the arsenical medications in use were withdrawn from the marketplace, leaving turkey producers with no tools to deal with the condition.
Speaking at the Midwest Poultry Federation Convention in Minneapolis, Minn., Dr. Brian Jordan of the University of Georgia indicated that controlling histomonas now relies more on flock management steps that interrupt the histomonas life cycle as part of a multi-factorial systems approach.
Histomonas can spread through direct consumption by turkeys of eggs or by turkeys consuming infected heterakis (cecal) worms, which are an intermediate host. Those cecal worms are very resistant parasites and can last for years in the environment, even if they are low pathogenic themselves, Jordan explained. Chickens can also host histomonas almost asymptomatically.
Therefore, Jordan said steps to control blackhead in turkeys include: limiting exposure by keeping chickens and turkeys off the same farm location, possibly for as long as five years; preventing exposure to cecal worms with the use of anthelmintics (but cecal worms may be developing resistance to some common anthelmintics); preventing turkeys from eating earthworms (which can also harbor histomonas), and proper house management, particularly when cleaning out a poultry house if the house has a soil pad under the litter that may contain earthworms.
Jordan also emphasized the importance of controlling coccidiosis in turkeys to minimize blackhead because coccidia can change the turkey's gut microbiota, creating an environment that is more hospitable to histomonas.