Astrovirus-Associated Polioencephalomyelitis in an Alpaca

An 8-year-old alpaca was admitted to the emergency service of the Clinic for Ruminants in Bern due to a reduced general condition and progressive neurological signs. Despite supportive treatment, its condition deteriorated and the animal had to be euthanized. Histopathological analysis revealed a severe non-suppurative polioencephalomyelitis with neuronal necrosis, most likely of viral origin. We detected abundant neuronal labelling with antibodies directed against two different epitopes of Bovine Astrovirus CH13/NeuroS1 (BoAstV-CH13/NeuroS1), which is a common viral agent associated with non-suppurative encephalitis in Swiss cattle. These findings were further verified by detection of viral RNA by use of in-situ hybridization and real-time RT-PCR. Next generation sequencing revealed that the detected virus genome had a pairwise identity of 98.9% to the genome of BoAstV-CH13/NeuroS1. To our knowledge, this is the first report of an astrovirus-associated polioencephalomyelitis in an alpaca. These results point to the possibility of an interspecies transmission of BoAstV-CH13/NeuroS1.