Arbovirus Seropositivity in UK Zoo-Housed Birds, with Evidence for Autochthonous Exposure to Batai Virus

Mosquito-borne virus transmission continues to increase in Europe, with the emergence of Usutu virus (USUV) in the United Kingdom (UK) in 2020 and the geographical expansion of West Nile virus (WNV) to more northerly latitudes. Other mosquito-borne viruses also circulate throughout mainland Europe, including Batai virus (BATV), leading to seropositivity in a range of vertebrate species, including humans, livestock and birds. A panel of archived sera from birds housed within a zoological collection in Central London was investigated for antibodies raised against the mosquito-borne viruses USUV, WNV and BATV. Orthoflavivirus seropositivity was detected in several birds, along with antibodies raised against BATV, an orthobunyavirus previously not reported in the UK. Furthermore, seropositivity in birds bred in captivity provides evidence of cryptic transmission of mosquito-borne viruses. This study highlights the utility of zoological collection birds as sentinels for VBD detection.