ARGAS (PERSICARGAS) GIGANTEUS SOFT TICK INFECTION WITH RICKETTSIA HOOGSTRAALI AND RELAPSING FEVER BORRELIA ON WILD AVIAN SPECIES OF THE DESERT SOUTHWEST, USA

摘要

Changing climatic conditions and the northward expansion of ticks and pathogens are of immense importance to human, animal, and environmental health assessment and risk management. From 2014 through 2015, a wildlife rehabilitation center in south-central Arizona, US noted soft ticks (Argasidae) infesting 23 birds, including Cooper's Hawks (Accipiter cooperii), Gray Hawks (Buteo plagiatus), Harris's Hawks (Parabuteo unicinctus), Red-tailed Hawks (Buteo jamaicensis), Great Horned Owls (Bubo virginianus), Common Ravens (Corvus corax), and a Greater Roadrunner (Geococcyx californianus), during the late summer seasonal rainy seasons. The parasites numbered in the hundreds on individual birds. Infested birds were moribund, obtunded, or paralyzed on presentation, with no prior histories of illness or evidence of trauma. Tick and avian blood samples were collected for vector-borne pathogen analysis focusing on the molecular detection of Rickettsia and Borrelia species. Ticks were identified as the neotropical species of soft tick, Argas (Persicargas) giganteus; their occurrence in the southern US on raptors represented an expansion of host range. Pathogen testing of ticks showed that 41% of 54 ticks were infected with Rickettsia hoogstraalii and 23% of 26 ticks were infected with a relapsing fever Borrelia; both agents are associated with uncertain health consequences. Among the blood samples, one was infected with the same Borrelia spp.; this Red-tailed Hawk also had Borrelia-positive ticks. With supportive therapy, the majority of birds, 74% (17/23), recovered and were released or permanent residents. The management of soft tick-infested birds and mitigation of future disease risk will require additional characterizations of these poorly studied soft ticks and their associated pathogens.