Limited detection of shared zoonotic pathogens in deer keds and blacklegged ticks co-parasitizing white-tailed deer in the eastern United States.

Deer keds, such as Lipoptena cervi Linnaeus (Diptera: Hippoboscidae), are blood-feeding flies from which several human and animal pathogens have been detected, including Borrelia burgdorferi sensu lato Johnson (Spirochaetales: Borreliaceae), the causative agent of Lyme disease. Cervids (Artiodactyla: Cervidae), which are the primary hosts of deer keds, are not natural reservoirs of B. burgdorferi sl, and it has been suggested that deer keds may acquire bacterial pathogens via co-feeding near infected ticks. We screened L. cervi (n = 306) and Ixodes scapularis Say (Ixodida: Ixodidae) (n = 315) collected from 38 white-tailed deer in Pennsylvania for the family Anaplasmataceae, Bartonella spp. (Hyphomicrobiales: Bartonellaceae), Borrelia spp., and Rickettsia spp. (Rickettsiales: Rickettsiaceae). Limited similarity in the bacterial DNA detected between these ectoparasites per host suggested that co-feeding may not be a mechanism by which deer keds acquire these bacteria. The feeding biology and life history of deer keds may impact the observed results, as could the season when specimens were collected. We separately screened L. cervi (n = 410), L. mazamae Róndani (n = 13), L. depressa Say (n = 10), and Neolipoptena ferrisi Bequaert (n = 14) collections from locations within the United States and Canada for the same pathogens. These results highlight the need to further study deer ked-host and deer ked-tick relationships.