While greatly reduced over the past 3 months, we continue to see scattered outbreaks of HPAI H5N8 in Europe. In June we saw outbreaks reported in Belgium, Luxembourg, France, and the UK (see ESA Epidemiological Update: HPAI H5 Clade 188.8.131.52 Viruses In Europe).
Today Italy's Istituto Zooprofilattico Sperimentale delle Venezie has confirmed a pair of outbreaks in Mantua Province, in northern Italy.
2016/2017 - H5N5, H5N82016 - H7N72014/2015 - H5N8, H5N12013 - H7N7
2016/2017 – H5N5, H5N8July 201721/07/2017 – On 20 July, the National Reference Laboratory (NRL) for Avian Influenza and Newcastle Disease confirmed as positive for Avian Influenza virus subtype H5N8 two farms located in Lombardy region: a rural holding and a fattening turkey industrial farm in Mantua province. Epidemiological investigations are ongoing in both outbreaks. An increase in mortality was reported in the previous days in one of the sheds of the industrial farm where about 18.900 fattening female turkeys (106 day-old) were present. Further information on virus characterization and on the cases will be provided as soon as available.
In the same date, Regional Authority of Lombardy notified a suspect of avian influenza in a laying hens farm (500.000 heads) in Mantua province.
Today, the NRL characterised both the viruses as Highly Pathogenic Avian Influenza.
The persistence of HPAI H5N8 in wild birds well into the summer - even at relatively low levels - is a decided change over what we've seen in previous years with this particular avian virus.
In 2015, after North America's biggest avian epizootic on record, the virus all but disappeared in the wild, and hasn't been reported in North American flocks in over two years (see PNAS: The Enigma Of Disappearing HPAI H5 In North American Migratory Waterfowl).But the virus that returned to Europe last fall had acquired significant changes (via reassortment) during the summer of 2016. In addition to being far more virulent in wild and migratory birds (see Europe: Unusual Mortality Among WIld Birds From H5N8), it also displayed the ability to infect a much wider range of birds (see ESA list of 78 species).
All of which means that we can't rely on the old `rules' necessarily applying going forward.