Investigation of H7N2 Avian Influenza Outbreaks in Two Broiler Breeder Flocks in Pennsylvania, 2001–02

摘要: Abstract An avian influenza (AI ) outbreak occurred in meat-type chickens central Pennsylvania from December 2001 to January 2002. Two broiler breeder flocks were initially infected almost simultaneously early December. Avian virus (AIV), H7N2 subtype, was isolated the two premises our laboratory. The isolates characterized as a low pathogenic strain at National Veterinary Services Laboratories based on molecular sequencing of hemagglutinin cleavage site and challenge studies specific-pathogen-free leghorn chickens. However, clinical observations pathologic findings indicated that this appeared be significantly under field conditions. Follow-up investigation spread rapidly within each flock. Within 7 days recognized start outbreak, over 90% seroconversion observed birds by hemagglutination inhibition test. A diagnosis AI made ...