RESUMEN
There are nine serotypes of avian paramyxovirus (APMV), including APMV-1, or Newcastle disease virus. Although free-flying ducks and geese have been extensively monitored for APMV, limited information is available for species in the order Charadriiformes. From 2000 to 2005 we tested cloacal swabs from 9,128 shorebirds and gulls (33 species, five families) captured in 10 states within the USA and in three countries in the Caribbean and South America. Avian paramyxoviruses were isolated from 60 (0.7%) samples by inoculation of embryonating chicken eggs; isolates only included APMV-1 and APMV-2. Two isolates (APMV-2) were made from gulls and 58 isolates (APMV-1 [41 isolates] and APMV-2 [17 isolates]) were made from shorebirds. All of the positive shorebirds were sampled at Delaware Bay (Delaware and New Jersey) and 45 (78%) of these isolates came from Ruddy Turnstones (Arenaria interpres). The APMV-1 infection rate was higher among Ruddy Turnstones compared with other shorebird species and varied by year. Avian paramyxovirus-2 was isolated from two of 394 (0.5%) Ruddy Turnstones at Delaware Bay in 2001 and from 13 of 735 (1.8%) Ruddy Turnstones during 2002. For both APMV-1 and APMV-2, infection rates were higher among Ruddy Turnstones sampled on the south shore of Delaware Bay compared to north shore populations. This spatial variation may be related to local movements of Ruddy Turnstones within this ecosystem. The higher prevalence of APMV in Ruddy Turnstones mirrors results observed for avian influenza viruses in shorebirds and may suggest similar modes of transmission.
Asunto(s)
Infecciones por Avulavirus/veterinaria , Avulavirus/aislamiento & purificación , Enfermedades de las Aves/epidemiología , Charadriiformes/virología , Reservorios de Enfermedades/veterinaria , Animales , Avulavirus/clasificación , Infecciones por Avulavirus/epidemiología , Infecciones por Avulavirus/transmisión , Infecciones por Avulavirus/virología , Enfermedades de las Aves/transmisión , Enfermedades de las Aves/virología , Región del Caribe/epidemiología , Cloaca/virología , Delaware/epidemiología , Reservorios de Enfermedades/virología , Femenino , Masculino , New Jersey/epidemiología , Serotipificación/veterinaria , América del Sur/epidemiología , Especificidad de la EspecieRESUMEN
Between 2006 and 2008, only one outbreak of highly pathogenic notifiable avian influenza (AI) was reported from the Americas, the Caribbean, and Australia. The outbreak, caused by H7N3, occurred in September 2007 in a multiage broiler breeder facility (approximately 49,000 birds) near Regina Beach in southern Saskatchewan, Canada. The disease was confined to a single farm; the farm was depopulated. All other reports of infections in poultry or wild birds involved low pathogenicity AI viruses. A notable event that occurred during the 3-yr period was the spread of low pathogenicity notifiable AI (LPNAI) H5N2 (Mexican lineage) into the Caribbean countries of the Dominican Republic and Haiti in 2007 and 2008, respectively, representing the first detection of AI reported in these countries. Mexico reported that the LPNAI H5N2 virus continued to circulate in the central regions of the country, and a total of 49 isolations were made from 12 states between 2006 and 2008. Also, during this period there was a significant increase in AI surveillance in many countries throughout the Americas, the Caribbean, and Australia, resulting in the detection of AI subtypes H1 through H12 and N1 through N9 in domestic bird species (chickens, turkeys, guinea fowl, upland game birds, and ducks/geese). The United States was the only one of these countries that reported detections of LPNAI (H5 or H7) infections in commercial poultry: one in chickens (H7N3, 2007), two in turkeys (H5N1 and H5N2, 2007), and one in pheasants (H5N8, 2008). Detections of AI viruses in wild birds between 2006 and 2008 were reported from North America (Canada and the United States), South America (Bolivia, Argentina, Chile, and Brazil), and Australia.
Asunto(s)
Gripe Aviar/epidemiología , Animales , Australia/epidemiología , Aves , Región del Caribe/epidemiología , Gripe Aviar/virología , América del Norte/epidemiología , América del Sur/epidemiología , Factores de TiempoRESUMEN
Between 2002 and 2005, three outbreaks of highly pathogenic avian influenza (HPAI) occurred in the Americas: one outbreak in Chile (H7N3) in 2002, one outbreak in the United States (H5N2) in 2004, and one outbreak in Canada (H7N3) in 2004. The outbreak in Chile was limited to a large broiler breeder operation and a nearby turkey flock and represented the first outbreak of HPAI in that country. The outbreak of HPAI in the United States occurred in Texas and was limited to one premise where chickens were raised for sale in nearby live-bird markets. The outbreak in Canada was the largest of the three HPAI outbreaks, involving 42 premises and approximately 17 million birds in the Fraser Valley, British Columbia. In each of the HPAI outbreaks, the disease was successfully eradicated by depopulation of infected farms. All other reports of infections in poultry and isolations from wild bird species pertained to low pathogenicity avian influenza (LPAI) viruses. Animal Health Officials in Canada reported subtypes H3, H5, and H6 in domestic poultry, and H3, H5, H11, and H13 from imported and/or wild bird species. An LPAI H5N2 virus continues to circulate in Mexico and the Central American countries of Guatemala and El Salvador. Each country reported isolations of H5N2 virus from poultry and the large-scale use of inactivated and recombinant H5 vaccines in their AI control programs. In Colombia, AI was reported for the first time when antibodies to H9N2 were detected in chickens by routine surveillance. Intensive surveillance activities in the United States detected AI virus or specific antibodies to 13 of the 16 hemagglutinin (H1-H13) and all nine neuraminidase subtypes in live-bird markets, small holder farms, and in commercial poultry from 29 states. The largest outbreak of LPAI in the United States occurred in 2002, when 197 farms were depopulated (4.7 million birds) to control an outbreak in Virginia and surrounding states. The outbreak was caused by an LPAI H7N2 virus closely related to an H7N2 virus that has been circulating in the live-bird marketing system in the northeastern United States since 1994.
Asunto(s)
Gripe Aviar/epidemiología , Secuencia de Aminoácidos , Animales , Aves , América Central/epidemiología , Brotes de Enfermedades/veterinaria , Virus de la Influenza A/genética , Gripe Aviar/virología , América del Norte/epidemiología , América del Sur/epidemiología , Factores de Tiempo , Proteínas Virales/química , Proteínas Virales/genéticaRESUMEN
An outbreak of avian influenza (AI) caused by a low-pathogenic H5N2 type A influenza virus began in Mexico in 1993 and several highly pathogenic strains of the virus emerged in 1994-1995. The highly pathogenic virus has not been reported since 1996, but the low-pathogenic virus remains endemic in Mexico and has spread to two adjacent countries, Guatemala and El Salvador. Measures implemented to control the outbreak and eradicate the virus in Mexico have included a widespread vaccination program in effect since 1995. Because this is the first case of long-term use of AI vaccines in poultry, the Mexican lineage virus presented us with a unique opportunity to examine the evolution of type A influenza virus circulating in poultry populations where there was elevated herd immunity due to maternal and active immunity. We analyzed the coding sequence of the HA1 subunit and the NS gene of 52 Mexican lineage viruses that were isolated between 1993 and 2002. Phylogenetic analysis indicated the presence of multiple sublineages of Mexican lineage isolates at the time vaccine was introduced. Further, most of the viruses isolated after the introduction of vaccine belonged to sublineages separate from the vaccine's sublineage. Serologic analysis using hemagglutination inhibition and virus neutralization tests showed major antigenic differences among isolates belonging to the different sublineages. Vaccine protection studies further confirmed the in vitro serologic results indicating that commercial vaccine was not able to prevent virus shedding when chickens were challenged with antigenically different isolates. These findings indicate that multilineage antigenic drift, which has not been observed in AI virus, is occurring in the Mexican lineage AI viruses and the persistence of the virus in the field is likely aided by its large antigenic difference from the vaccine strain.
Asunto(s)
Subtipo H5N2 del Virus de la Influenza A , Virus de la Influenza A/inmunología , Vacunas contra la Influenza/inmunología , Secuencia de Aminoácidos , Animales , Evolución Biológica , Pollos , Pruebas de Inhibición de Hemaglutinación , Glicoproteínas Hemaglutininas del Virus de la Influenza/genética , Sueros Inmunes/inmunología , Virus de la Influenza A/genética , Virus de la Influenza A/patogenicidad , Datos de Secuencia Molecular , FilogeniaRESUMEN
Influenza A viruses occur worldwide in wild birds and are occasionally associated with outbreaks in commercial chickens and turkeys. However, avian influenza viruses have not been isolated from wild birds or poultry in South America. A recent outbreak in chickens of H7N3 low pathogenic avian influenza (LPAI) occurred in Chile. One month later, after a sudden increase in deaths, H7N3 highly pathogenic avian influenza (HPAI) virus was isolated. Sequence analysis of all eight genes of the LPAI virus and the HPAI viruses showed minor differences between the viruses except at the hemagglutinin (HA) cleavage site. The LPAI virus had a cleavage site similar to other low pathogenic H7 viruses, but the HPAI isolates had a 30-nucleotide insert. The insertion likely occurred by recombination between the HA and nucleoprotein genes of the LPAI virus, resulting in a virulence shift. Sequence comparison of all eight gene segments showed the Chilean viruses were also distinct from all other avian influenza viruses and represent a distinct South American clade.