Occurrence of reovirus infection in Muscovy ducks (Cairina moschata) in south western Poland

During the summer 2012 an incidence of high mortality, above 44 percent, in two flocks of Muscovy ducklings in Poland was noted. The clinical signs included considerable weight loss and inability to walk. During the post-mortem evaluations dehydration and enteritis, gouty kidneys as well as hemorrhagic liver and spleen lesions were found. The laboratory diagnosis included agar gel precipitation assay (AGP) as well as polymerase chain reaction (PCR) or reverse transcription PCR for the presence of goose parvovirus (GPV), duck circovirus (DuCV), duck reovirus (DRV) and avian reovirus (ARV). Interestingly, the examinations performed by AGP showed partial reactivity of liver homogenates from Muscovy ducklings with chicken S1133 antiserum. The presence of duck reovirus RNA was also detected by real-time RT-PCR targeting the chicken reovirus sigma NS fragment, while the sequencing showed major similarity to chicken S1133, 1733, GX/2010/1 and TARV-MN2 reovirus strains. The virus sequence was also related to a previously isolated TH11 strain from Muscovy ducks in China. Further study is needed in order to explain the particular epidemiology of the reovirus infection of Muscovy ducklings.