Detection of Rickettsia hoogstraalii and Rickettsia lusitaniae in Argas (Persicargas) ricei Ticks Infesting California Condors (Gymnogyps californianus).

The California Condor (Gymnogyps californianus) is the largest North American land bird and an endangered species. In September 2024, the Bitter Creek National Wildlife Refuge reported a heavy soft tick infestation on three juvenile condors that were to be released to the wild. One was transported to Los Angeles Zoo for treatment because it showed clinical signs associated with tick paralysis, a neurotoxin-mediated paralytic syndrome. The others had slight weight loss and extensive scabbing in the areas that had previous tick burdens. Eight ticks found on perches in the flight pen were identified as Argas (Persicargas) ricei. Pathogen testing of those ticks found four positives for Rickettsia hoogstraalii, a species previously detected in raptors and their soft ticks in the southwestern USA. One tick was positive for Rickettsia lusitaniae, associated with soft ticks in bats worldwide and closely related to Rickettsia felis and R. hoogstraalii. No ticks were positive for Borrelia spp. Blood meal analysis confirmed that the California Condor was the associated host for a subset of tested ticks. All condors improved clinically with ectoparasite treatment and supportive care. These findings suggest a clear interaction between A. ricei ticks and condors. Managers should consider the checking and removal of ticks from temporary bird housing and prophylactic or event-based treatments of translocated birds; further, Rickettsia species could be considered in future wildlife health investigations.