Abstract
Between October 2016 and December 2017, several European Countries had been involved in a massive Highly Pathogenic Avian Influenza (HPAI) epidemic sustained by H5N8 subtype virus. Starting on December 2016, also Italy was affected by H5N8 HPAI virus, with cases occurring in two epidemic waves: the first between December 2016 and May 2017, and the second in July-December 2017. Eighty-three outbreaks were recorded in poultry, 67 of which (80.72%) occurring in the second wave. A total of 14 cases were reported in wild birds. Epidemiological information and genetic analyses were conjointly used to get insight on the spread dynamics. Analyses indicated multiple introductions from wild birds to the poultry sector in the first epidemic wave, and noteworthy lateral spread from October 2017 in a limited geographical area with high poultry densities. Turkeys, layers and backyards were the mainly affected types of poultry production. Two genetic sub-groups were detected in the second wave in non-overlapping geographical areas, leading to speculate on the involvement of different wild bird populations. The integration of epidemiological data and genetic analyses allowed to unravel the transmission dynamics of H5N8 virus in Italy, and could be exploited to timely support in implementing tailored control measures.
Highlights
Between October 2016 and December 2017, Highly Pathogenic Avian Influenza (HPAI) outbreaks sustained by H5N8 subtype viruses were reported in several European Countries
After the massive epidemics of HPAI and Low Pathogenicity Avian Influenza (LPAI) viruses in late 1990s and early 2000s, only sporadic incursions with limited outbreaks were observed until 201610,11
Hereby we present a detailed description of the Italian H5N8 HPAI epidemic, which proved having interesting characteristics that could help in better understanding the AI spread dynamics in absence of migratory movements, as most of the outbreaks in poultry were detected in Summer/Autumn-time 2017
Summary
Between October 2016 and December 2017, Highly Pathogenic Avian Influenza (HPAI) outbreaks sustained by H5N8 subtype viruses were reported in several European Countries. The hemagglutinin (HA) gene segments of the two circulating H5 subtypes were genetically related to H5N8 viruses found in wild birds in Qinghai Lake (China) during May 2016 and in Uvs-Nuur Lake (Siberia) in June 2016 These findings suggested the likely westward dissemination of the virus from Siberia to Europe, via the late-summer/autumn migratory movements of wild waterfowl[5,7,8]. Repeatedly experienced the circulation of both HP and Low Pathogenicity (LP) Avian Influenza viruses in the past two decades This was mainly due to high concentrations of susceptible poultry production types (e.g. fattening turkeys and laying hens) in a limited geographic areas, defined Densely Populated Poultry Areas (DPPAs) along migratory flight paths (i.e. Black Sea – Mediterranean and The East Atlantic flyways), and in proximity to large wetlands[9]. The integration of epidemiological data and genetic analyses allowed to generate and/or corroborate hypotheses on the evolution of the epidemic, and could be exploited in almost a real-time fashion to support decision-makers in enhancing biosecurity measures and implementing tailored control measures
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