Cormorants as Potential Victims and Reservoirs of Velogenic Newcastle Disease Virus (Orthoavulavirus-1) in Central Asia.

Abstract

Virulent strains of avian orthoavulavirus 1, historically known as Newcastle disease virus (NDV), are widespread and cause high levels of mortality in poultry worldwide. Wild birds may play an important role in the maintenance ofin nature. Prior to 2014, most of the lentogenic NDV strains isolated from Central Asia were obtained from the avian order Anseriformes (ducks and geese). Wild birds were monitored from 2014-2016 to detect the circulation of NDV. A total of 1522 samples belonging to 73 avian species were examined, and 26 positive samples were identified. The isolates ofbelonged to three genotypes: viruses from doves (Columbiformes) and cormorants (Suliformes) were attributed to the velogenic genotypes VI and XIII, respectively, while the isolate from poultry belonged to lentogenic genotype I. The isolation offrom doves may confirm their role as a reservoir of pigeon paramyxoviruses (antigenic variant of the genotype VI NDV) in nature and indicates the potential threat of introduction of velogenic strains into the poultry population. Our study describes an epizootic scenario in Kazakhstan among cormorants with mortality among juveniles of up to 3 wk of age and isolation of the NDV from apparently healthy birds. These observations may support the idea that cormorants are one of the potential reservoirs and victims of velogenicin Central Asia. The seasonal migrations of cormorants may partially contribute to viral dissemination throughout the continent; however, this hypothesis needs more evidence.