First Molecular Detection of the Poultry Pathogen Protozoan Histomonas meleagridis from Red Mite (Dermanyssus gallinae)

Our study reports the first molecular detection of the protozoan pathogen Histomonas meleagridis, the causative agent of histomonosis, in the poultry red mite Dermanyssus gallinae. Mite samples were collected from a commercial poultry farm and a backyard flock in Hungary and analyzed using PCR assays that targeted the COX1 gene in mites and 18S rRNA gene in H. meleagridis. Phylogenetic analysis confirmed the identity of D. gallinae and revealed distinct genetic lineages between farm and backyard isolates. H. meleagridis DNA was detected in 10 of 17 mite samples, representing multiple variants within Genotype 1. No histomonosis was detected in the examined poultry, although one hen harbored Simplicimonas sp. The findings suggest that D. gallinae could serve as a carrier for H. meleagridis, potentially facilitating the persistence and transmission of the pathogen. This novel host–pathogen association highlights the need for further research into the epidemiological role of poultry ectoparasites in the spread of histomonosis.