Persistence and vertical transmission of chicken anaemia agent in experimentally infected laying hens.

Irrespective of route of infection and age of hens at infection chicken anaemia agent (CAA) was excreted via faeces repeatedly during the first 5 weeks postinfection. Eggs, embryos and chicks of hens infected as chicks were free of CAA, but CAA was found in a small number of embryos and hatched chicks of hens infected during the laying period. Re-infection of hens resulted in shedding of CAA via the faeces for a period of 4 days, but no CAA was found in eggs, embryos and chicks. Immunofluorescent and serum neutralization antibody against CAA were demonstrated 2 weeks post-infection. They persisted for at least 6 months. Reinfection with CAA led to a significant increase of both immunofluorescent and serum neutralization antibody titres.