Abstract Background Louse flies (Diptera: Hippoboscidae), commonly known as keds or flat flies, are a family of insects that are obligate ectoparasites of birds and mammals, with 216 species documented worldwide. Approximately 75% of the species in the Hippoboscidae family infest birds, while the remaining 25% infest various mammals. Despite the diversity within this family, understanding of their prevalence, vector competencies, and geographic distribution is still quite limited. Methods From August 2023 to December 2024, louse flies were collected from wild raptors brought for rehabilitation to the Riverbanks Zoo and Garden in Columbia, South Carolina, USA, as part of a surveillance study. Ectoparasites were removed and stored in 75% ethanol (initially) and DNA/RNA Shield (later), and comprehensive health reports were obtained for all admitted birds of prey. Zoo staff collected saliva samples from a subset of raptors with attached flies, and all samples were tested for West Nile virus (WNV) via real-time polymerase chain reaction (RT-PCR). Results Over the 16-month study, approximately 75 louse flies were collected from 21 birds representing six avian species. The most louse flies collected were Icosta americana (Leach, 1817), while only two samples contained Icosta rufiventris , a species previously unreported in South Carolina. Louse flies were pooled for RT-PCR testing, yielding 36 fly pools with an overall 42% WNV positivity rate. Twelve raptor saliva samples were also available for WNV testing; of these, four (33%) tested positive. Conclusions This represents the first WNV analysis in avian louse flies collected in South Carolina and, to our knowledge, includes the first report of Icosta rufiventris in the region. Discordant results between raptor WNV infection and the presence of attached ectoparasite WNV underscore a major knowledge gap within the scientific community regarding the role of avian louse flies in the WNV transmission cycle. Further research is needed to determine whether louse flies represent a potential WNV vector for birds. Graphical Abstract
Brown et al. (Tue,) studied this question.