Incursion and Spread of H5N1 Highly Pathogenic Avian Influenza Viruses among Wild Birds in 2010–11 Winter in Japan

Abstract

ABSTRACT. Many highly pathogenic avian influenza (HPAI) outbreaks occurred in Japan during the 2010-11 winter. H5N1 HPAI viruses were isolated from 63 wild birds including migrating and resident birds, and caused HPAI outbreaks in 24 chicken farms by the end of March. In the present study, all virus strains isolated from wild birds in western Japan together with the viruses in the preceding works were phylogenetically and epidemiologically analyzed. Furthermore, the virus distributions in the raptors that died of H5N1 HPAI virus infection were assessed. The virus isolates in Japan were classified into three groups by phylogenic analysis of their hemagglutinins, supporting the previous report (Sakoda et al., 2012). The viruses in each group were continuously isolated in respective limited areas, indicating that viruses were maintained in local bird populations throughout the outbreak periods. Some viruses were genetically closely related to the Korean isolates around the same periods, suggesting that migratory birds were suspected of contributing to transportation of the viruses across the sea. Viruses were recovered from systemic tissues including digestive organs of the deceased raptors, indicating that they were infected with HPAI viruses by their predatory behavior, eating infected birds or carrion in the environment. KEY WORDS: H5N1, influenza virus, Japan, wild bird.

Human H7N9 avian influenza virus infection: a review and pandemic risk assessment

“… 99 Proper disposal of infected poultry and animal carcasses is important in preventing the spread of nH7N9 via predatory or scavenger birds. 100 , 101 , 102 …”

Hemato-biochemical and pathological changes on avian influenza in naturally infected domestic ducks in Egypt

“…The virus (HPAI) H5N1 transformed from sporadic outbreaks in poultry to persistent circulation in terrestrial and aquatic poultry and potentially in wild waterfowl [ 12 ]. In addition leading to, serious economic losses in the poultry industry [ 13 ]. Outbreaks associated with the AIV have increased since 2009 [ 14 ].…”

Spatial assessment of the potential risk of avian influenza A virus infection in three raptor species in Japan

“…Furthermore, the northern goshawk might have fewer opportunities to consume infected prey. Raptors generally become infected with avian influenza A viruses by feeding on infected prey or carrion [ 1 , 55 ]. Since most of the HPAI-H5N1 infected birds have been waterfowl [ 53 , 55 ], if the northern goshawk had fewer opportunities to hunt, then the results of the present study should be reasonable.…”

“…Correlation coefficients were also calculated between habitat suitability indices and avian influenza A risk indices. Carcasses infected with HPAI-H5N1 have been reported for one mountain hawk-eagle, one northern goshawk and nine peregrine falcons in Japan [ 27 , 53 , 55 ]. These sites were illustrated in the risk map for each species to validate reliability of the maps.…”

“…In the present study, we created habitat suitability maps for three raptor species and superimposed them on the risk map for avian influenza A during the winter (created in our previous study) [ 44 ]. The target raptor species were the mountain hawk-eagle Nisaetus nipalensis , northern goshawk Accipiter gentilis and peregrine falcon Falco peregrinus , which succumbed to HPAI-H5N1 infection during the winter in Japan [ 27 , 53 , 55 ]. These species are native to Japan and spend the entire winter in various areas of the country [ 56 ].…”