Mortality associated with avian reovirus infection in a free-living magpie (Pica pica) in Great Britain

Abstract

BackgroundAvian reoviruses (ARVs) cause a range of disease presentations in domestic, captive and free-living bird species. ARVs have been reported as a cause of significant disease and mortality in free-living corvid species in North America and continental Europe. Until this report, there have been no confirmed cases of ARV-associated disease in British wild birds.Case presentationSporadic individual magpie (Pica pica) mortality was detected at a single site in Buckinghamshire, England, April-September 2013. An adult female magpie was found moribund and subsequently died. Post-mortem examination identified hepatomegaly and splenomegaly as the most severe macroscopic abnormalities. Histopathological examination revealed extensive hepatic and splenic necrosis. Transmission electron microscopy (TEM) identified virions of a size (circa 78 nm diameter) and morphology consistent with ARV in both the liver and the small intestinal (SI) contents. Nucleic acid extracted from pooled liver and spleen was positive on both a pan-reovirus nested PCR targeting the RNA-dependent RNA polymerase gene and a PCR using primers specific to the ARV sigma C protein gene. Virus isolated from the liver and the SI contents was characterised by a syncytial-type cytopathic effect, a reovirus-like appearance on TEM and sequence identical to that from PCR of tissues. In situ hybridisation confirmed co-localisation of ARV with lesions in the liver and spleen, implicating ARV as the causative agent. Splenic lymphoid atrophy and necrotic stomatitis associated with Aspergillus fumigatus infection were consistent with generalised immunosuppression and resultant opportunistic infection.ConclusionsThe pathology and comprehensive virus investigations in this case indicate ARV as the primary pathogen in this magpie, with concurrent secondary infection subsequent to immunosuppression, as has been observed with reoviral infections in other bird species. ARV should be considered as a differential diagnosis for magpie, and potentially other corvid, disease and mortality incidents. This is the first demonstration of ARV-associated mortality in a wild bird in Britain. The prevalence and significance of ARV infection in British wild birds, and its implications for poultry and captive bird health, are currently unknown.

A 5-Year Retrospective Review of Avian Diseases Diagnosed at the Department of Pathology, University of Georgia

“…infections, which are often the cause of mortality (Raue et al, 2005;Marlier and Vindevogel, 2006). The present study is consistent with past studies of corvid reoviral infections in that the liver, spleen, intestine and heart are commonly affected (Affolter et al, 2007;Lawson et al, 2015), which primarily manifest as hepatic and splenic necrosis, haemorrhagic or necrotizing enteritis, and extensive cardiac necrosis with mild inflammation (Affolter et al, 2007).…”

A Review of Pathogen Transmission at the Backyard Chicken–Wild Bird Interface

“…It has also been reported in songbirds of the Paridae family (192), wild turkeys (Meleagris gallopavo) in the Southeastern United States (193), and rock pigeons (Columba livia) in Turkey (194). Corvids appear to be particularly susceptible to infection with avian reovirus (195), a poultry pathogen also commonly detected in backyard chickens (112,196). In addition, two dieoffs of American Woodcocks (Scolopax minor) were attributed to the virus (197).…”

Detection of avian reoviruses in wild birds in Poland

“…Recent reports have described ARV as a cause of serious disease and/or mortality in free-living corvid species in Great Britain and Finland ( 5 , 10 ). ARV strain detected in a free-living magpie was genetically related to chicken origin reoviruses, reinforcing the hypothesis on the possible reservoir role of wild birds in reovirus transmission ( 10 ). Ogasawara et al ( 18 ) isolated a novel orthoreovirus strain from a dead brown-eared bulbul (order Passeriformes ) in Japan.…”

“…Several reports have described ARV as a cause of serious diseases and mortality in free-living corvid species. Lawson et al ( 10 ) presented a case of ARV infection in a wild magpie ( Pica pica ) from England. Recently, a novel orthoreovirus strains have been isolated from partridge ( Perdix perdix ) and brown-eared bulbul ( Hypsipetes amaurotis ) ( 9 , 18 ).…”