Rickettsia and Ehrlichia of Veterinary and Public Health Importance in Ticks Collected from Birds in the Great Plains of the United States

As the incidence of tick-borne disease expands globally, comprehensive understanding of pathogen reservoir hosts is crucial to protect humans and wildlife. While many components are understood, there are gaps in our knowledge regarding the role of alternative, non-mammalian hosts such as birds. Within the United States, birds have been identified as reservoirs for Borrelia and Rickettsia; however, local studies rarely examine the potential of birds as reservoirs and transporters of Ehrlichia-infected ticks, unlike studies in Europe and South America. To address this research gap, we extracted and sequenced important microorganisms within 90 larval and nymphal ticks which were removed from passerine and near-passerine birds in the Great Plains region of the United States between May and October 2023. We found that 11% of birds hosted ticks infected with one or more Rickettsia or Ehrlichia species. Additionally, we collected a larval Haemaphysalis leporispalustris infected with Ehrlichia chaffeensis from a Northern Cardinal, the first North American songbird implicated in the Ehrlichia transmission cycle. Our research intertwines multiple bird and tick species in the North American pathogen system, highlighting the need for continued research focusing on birds as tick hosts and pathogen reservoirs in understudied parts of the United States.