Influenza virus surveillance in waterfowl in Pennsylvania after the H5N2 avian outbreak

During the latter stages of the lethal H5N2 influenza eradication program in domestic poultry in Pennsylvania in 1983-84, surveillance of waterfowl was done to determine if these birds harbored influenza viruses that might subsequently appear in poultry. From late June to November 1984, 182 hemagglutinating viruses were isolated from 2043 wild birds, primarily ducks, in the same geographical area as the earlier lethal H5N2 avian influenza outbreak. The virus isolates from waterfowl included paramyxoviruses (PMV-1, -4, and -6) and influenza viruses of 13 antigenic combinations. There was only one H5N2 isolate from a duck. Although this virus was antigenically related to the lethal H5N2 virus, genetic and antigenic analysis indicated that it could be discriminated from the virulent family of H5N2 viruses, and it did not originate from chickens. Many of the influenza viruses obtained from wild ducks were capable of replicating in chickens after experimental inoculation but did not cause disease. These studies show that many influenza A virus strains circulating in waterfowl in the vicinity of domestic poultry in Pennsylvania did not originate from domestic poultry. These influenza viruses from wild ducks were capable of infecting poultry; however, transmission of these viruses to poultry apparently was avoided by good husbandry and control measures. /// Se realizó una vigilancia epidemiológica en aves acuáticas con el fin de determinar si éstas fueron portadoras de virus influenza que pudieron haber aparecido después en aves domésticas. Este estudio se llevó a cabo durante las últimas etapas del programa de erradicación realizado en aves domésticas en el estado de Pensilvania entre 1983 y 1984. Desde finales de Junio de 1984, se aislaron 182 virus hemaglutinantes a partir de 2043 aves silvestres, principalmente patos, procedentes de la misma área geográfica dónde ocurrió el primer brote de influenza con el virus letal H5N2. Los aislamientos obtenidos a partir de aves acuáticas incluyeron paramixovirus (tipos PMV-1, 4 y 6) y 13 distintas combinaciones antigénicas de virus influenza. Sólo hubo un aislamiento del serotipo H5N2 a partir de un pato. Aunque este último guarda relación antigénica con el virus letal H5N2, no se originó a partir de pollos y fué descartado como miembro de la familia de los virus H5N2 virulentos mediante análisis genéticos y antigénicos. Muchos de los virus influenza aislados de patos mostraron capacidad para replicarse en pollos pero s