A survey of the viral flora of two commercial Pekin duck flocks

Abstract

Ducklings on a problem farm which showed persistent and unacceptably high mortality yielded a larger range and greater number of viruses than did ducklings from a second flock, in which mortality was of a power and acceptable level. Reoviruses were the viruses most frequently isolated from young birds from both farms, but for longer at the problem site. ELAs (Embryo Lethal Agents), named since they caused high mortality in chick embryos, but could not otherwise be characterized, were recovered frequently and throughout the growth cycle of the problem flock, but not at all in the other flock. Lentogenic Newcastle disease virus was detected at all ages on the problem farm but less often than ELAs. The faeces of birds on the problem farm yielded rota-like viruses, corona-like viruses and adeno-like viruses, and on the farm with normal mortality, Egg Drop Syndrome-76 virus and adenovirus. Detection techniques included culture on chick embryos and chick embryo liver cells, and electron microscopy (EM). Inoculation of whole eggs was particularly valuable and more successful than cell culture for virus recovery. EM was most useful for direct examination of faecal preparations and confirmation of the viral type.