Living in the city: Angiostrongylus cantonensis is a novel threat to an urban population of Florida burrowing owls (Athene cunicularia floridana) in south Florida

Background: Angiostrongylus cantonensis , the rat lungworm, is a metastrongyloid parasite that uses rodents as definitive hosts, mollusks as intermediate hosts, and a wide range of invertebrate and vertebrate species as paratenic hosts. Although this parasite poses a significant public health concern in many regions of the world, it can also cause disease in numerous domestic and wildlife aberrant host species. When parasite larvae are ingested by one of these aberrant hosts, larval migration in the central nervous system causes extensive damage, resulting in spinal cord and/or brain damage and inflammation, leading to potentially fatal neurological disease. We describe the detection of A. cantonensis in a novel host, the Florida burrowing owl ( Athene cunicularia floridana ) on Marco Island, Collier County, Florida. The Florida burrowing owl is a state-listed species that has experienced steep population declines across its range, primarily due to habitat loss and fragmentation. Many populations are now restricted to urban environments, which pose novel threats to the owls, such as exposure to anticoagulant rodenticides and novel pathogens, increased risk of predation, vehicular strike, and increased disturbance at nest sites. Methods and Results: Through diagnostic evaluation of carcasses and select tissues submitted to the Southeastern Cooperative Wildlife Disease Study from 2019 to 2023, we diagnosed nine confirmed or suspected cases of angiostrongylosison Marco Island. Microscopic examination and PCR testing confirmed parasite identification. Additionally, ancillary testing ruled out other potential causes of neurological disease, such as rodenticides, West Nile virus, and highly pathogenic avian influenza virus. Conclusions: This study underscores the importance of surveillance and monitoring efforts for A. cantonensis , particularly in regions where novel hosts may serve as indicators of public health risk. Additionally, as urbanization and habitat fragmentation continue encroaching upon wildlife habitats, understanding the dynamics of host-parasite interactions becomes crucial for mitigating the spread of zoonotic diseases.