Severe neurologic disease and chick mortality in crested screamers (Chauna torquata) infected with a novel Gyrovirus

Highlights: • Crested screamers were infected with viruses related to chicken anemia virus. • Infected chicks at a zoo experienced lethal neurologic disease over two years. • The disease featured immune cell depletion and neurodegeneration. • The virus is a new lineage, with persistent infection and co-infection common. • "Screamer anemia virus," if causal, expands the known biology of gyroviruses. Gyroviruses are small, single stranded DNA viruses in the family Anelloviridae. In chickens, the type virus (chicken anemia virus; CAV) causes epidemic disease in poultry flocks worldwide. In 2007 and 2008, young crested screamers (Chauna torquata) at a zoo in Wisconsin, USA, died of neurologic disease with clinical and pathological features resembling CAV infection. Conventional diagnostics were negative, but molecular analyses revealed coinfection of an affected bird with three variants of a novel Gyrovirus lineage, GyV10. Analysis of ten additional screamers from this and another zoo revealed infection in all but one bird, with co-infections and persistent infections common. The association between GyV10 ("screamer anemia virus," provisionally) and the disease remains unproven, but certain immunological and neurologic features of the syndrome would expand the known pathologic consequences of Gyrovirus infection. To control the virus, autogenous vaccines, environmental decontamination, and management strategies to limit vertical and horizontal transmission might prove effective.