Surveillance for High Pathogenicity Avian Influenza Virus in Wild Birds in the Pacific Flyway of the United States, 2006–2007

Abstract

SUMMARY. In 2006 the U.S. Department of Agriculture, U.S. Department of Interior, and cooperating state fish and wildlife agencies began surveillance for high-pathogenicity avian influenza (HPAI) H5N1 virus in wild birds in the Pacific Flyway of the United States. This surveillance effort was highly integrated in California, Oregon, Washington, Idaho, Nevada, Arizona, Utah, and western Montana, with collection of samples coordinated with state agencies. Sampling focused on live wild birds, hunterkilled waterfowl during state hunting seasons, and wild bird mortality events. Of 20,888 samples collected, 18,139 were from order Anseriformes (waterfowl) and 2010 were from order Charadriiformes (shorebirds), representing the two groups of birds regarded to be the primary reservoirs of avian influenza viruses. Although 83 birds were positive by H5 real-time reverse transcription polymerase chain reaction (rRT-PCR), no HPAI H5N1 virus was found. Thirty-two virus isolates were obtained from the H5-positive samples, including low-pathogenicity H5 viruses identified as H5N2, H5N3, and H5N9.RESUMEN. Muestreo para detectar influenza aviar de alta patogenicidad en aves silvestres de la ruta migratoria del Pacífico de los Estados Unidos, 2006Unidos, -2007 En el año 2006 el Departamento de Agricultura y el Departamento del Interior de los Estados Unidos, con la cooperación de agencias estatales de pesca y vida silvestre iniciaron un muestreo para detectar la influenza aviar de alta patogenicidad subtipo H5N1 en aves silvestres de la ruta migratoria del Pacífico de los Estados Unidos. Este proyecto estuvo integrado principalmente en California, Oregón, Washington, Idaho, Nevada, Arizona, Utah, y la parte oeste de Montana, con la recolección de muestras coordinada por las agencias estatales. El muestreo estuvo enfocado en aves silvestres vivas, aves acuáticas muertas por cazadores durante las estaciones de caza y en eventos de mortalidad de aves silvestres. De las 20,888 muestras recolectadas, 18,139 muestras fueron de aves del orden Anseriformes (aves acuáticas) y 2010 fueron de aves del orden Caradriformes (aves playeras), que representan los dos grupos de aves considerados como los principales reservorios de los virus de influenza aviar. Aunque 83 aves fueron positivas para la hemaglutinina 5 (H5) por la prueba de transcripción reversa y reacción en cadena de la polimerasa en tiempo real, no se encontró la presencia del virus de alta patogenicidad subtipo H5N1. Treinta y dos aislamientos fueron obtenidos de las muestras positivas a H5, incluyendo virus de baja patogenicidad identificados como H5N2, H5N3 y H5N9.

Multiyear Surveillance for Avian Influenza Virus in Waterfowl from Wintering Grounds, Texas Coast, USA

“…Detection of AIV at low levels throughout the wintering season supports the contention that AIV can persist in wild-bird populations through continuous circulation in a proportion of the population ( 1 ). The low rate of virus isolation observed in the current study (29.9% of rRT-PCR–positive samples) is consistent with findings of other studies and is not surprising ( 2 , 23 ). Real-time RT-PCR is considered more sensitive than virus isolation, enabling the detection of genome fragments and viruses that do not grow in embryonated chicken eggs.…”

“…These viruses, which are occasionally transmitted to other species, including humans, poultry, and swine, result in subclinical to highly pathogenic diseases. Two subtypes (H5 and H7) have been most frequently associated with high pathogenicity in poultry and are of considerable interest to the poultry industry and to researchers who study avian influenza viruses (AIVs) ( 2 – 4 ). The migratory nature of many waterfowl species and the persistence of AIV in them present a potential vehicle for global dissemination of influenza viruses, as well as a constant source of viruses and genetic material for new pandemic strains.…”

Influenza A Virus Surveillance in Waterfowl in Missouri, USA, 2005–2013

“…The findings of the current study are comparable to the results of other investigators where the recorded IAV prevalence varies over seasons and is influenced by the age and species of the sampled birds (3,5,18,25). The present surveillance study demonstrated an IAV prevalence of 2.7% in the sampled wild bird population.…”

“…Most attention is given to waterfowl-origin H5 and H7 IAVs because they are the HA subtypes that have demonstrated potential for high pathogenicity among birds (20). In addition to highly pathogenic (HP) IAVs, low pathogenic (LP) IAVs are also concerning for poultry producers because of the threat they pose to overall flock health and production (3,15). Beyond poultry, avian-lineage IAVs have impacted swine health as well; most notably, North American avian-lineage gene segments (PB2 and PA) are part of the triple-reassortant internal gene cassette that has been circulating in pigs since 1998 (26).…”

Community-Level Differences in the Microbiome of Healthy Wild Mallards and Those Infected by Influenza A Viruses

“…), IAVs contain gene segments that trace back to a wild avian origin (3, 4). Recent concern over the emergence of new pandemic IAVs led to intensive IAV surveillance in waterfowl, especially of dabbling ducks in the genus Anas , which revealed that IAV prevalence may reach 40%, especially in young (hatch year) birds (58–61, 65). In contrast to humans, where IAVs infect the respiratory tract and cause significant morbidity and mortality, IAVs infect the gastrointestinal tract of waterfowl and cause little or no pathology (5) and are spread by fecal-oral transmission (6).…”