Encephalitis and Death in Wild Mammals at a Rehabilitation Center after Infection with Highly Pathogenic Avian Influenza A(H5N8) Virus, United Kingdom
T. Floyd, Ashley C. Banyard, Fabian Z. X. Lean, Alexander M. P. Byrne, Edward Fullick, Elliot Whittard, Benjamin C. Mollett, Steve Bexton, Vanessa Swinson, Michele Macrelli, Nicola S. Lewis, Scott M. Reid, Alejandro Núñez, Jennifer Duff, Rowena Hansen, Ian H. Brown
Abstract
A n episode of unusual disease resulting in deaths in different species at a wildlife rehabilitation center in the United Kingdom during late 2020 led to the retrospective detection of infl uenza A virus subtype H5N8 of avian origin in 5 mute swans, a fox, and 3 seals. The wildlife rehabilitation center admits >6,000 animals each year. New arrivals are initially housed in a quarantine facility upon admission. Four juvenile common seals (Phoca vitulina), 1 juvenile gray seal (Halichoerus grypus), and 1 juvenile red fox (Vulpes vulpes) died or were euthanized over a 2-day period. The fox died suddenly after a short period of nonspecifi c malaise and inappetence. The seals exhibited sudden-onset neurologic signs, including seizures before death or euthanasia (Figure This mortality event occurred 1 week after the deaths or euthanasia of 5 mute swans (Cygnus olor) held in isolation at the center because of acute-onset malaise and terminal seizures. The 5 swans were submitted for examination and testing under the Avian Infl uenza Wild Bird Surveillance Scheme (undertaken by the United Kingdom's Animal and Plant Health Agency) (1), and they tested positive for highly pathogenic avian infl uenza A(H5N8) virus.