Quick Review of the litterature - Biosecurity and surveillance are highlighted

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The highly pathogenic avian influenza (HPAI) subtype H5N2 affecting turkey and egg producing flocks in the upper Midwest in United States last year, has been considered the most severe emergency animal disease experienced by the United States. From March through to mid-June 2015, the HPAI subtype H5N2 infection was responsible for the depletion of 35 million laying hens, approximately 4 million replacement pullets and 7 million turkeys. The pathogen involved was a reassortant with the H5 genes derived from Eurasian avian influenza (AI) strains and the neuraminidase genes from AI isolates identified in North American waterfowl.

A recent letter to Emerging Infectious Diseases published in January 2016 summarized important findings,  noting that the spread of the disease occurred from south to north which did not correlate to the typical direction of waterfowl migration, from west to east. Unlike the earlier outbreaks in poultry in Canada, the outbreaks in midwestern states, did not have corresponding high numbers of virus in  wild bird populations in surrounding regions. “The combination of high poultry densities and timing of waterfowl migration have likely predisposed Minnesota and Iowa to outbreaks of avian influenza among poultry flocks. However, consistent with US Department of Agriculture findings, local factors have likely also contributed to the large number of outbreaks in these states.”[1]

Waterfowl have a role mainly in primary AI virus incursion. However, biosecurity could be a critically important factor to limit disease spread. It has been considered that in areas with a high density of poultry, commensurate capital expenditure on structural biosecurity and upgrading operational biosecurity, coupled with a marked change in culture are essential to prevent disease spread.

Since the incursion of new H5N8 in Europe, the Food and Agriculture Organization (FAO) and OIE (World Organization for Animal Health) highlighted the need for better biosecurity.  “Should poultry systems with low-biosecurity conditions become infected in countries with limited veterinary preparedness, the virus could spread through farms with devastating effects, both on vulnerable livelihoods as well as on country economies and trade. The best way for countries to safeguard against these impacts is to encourage better biosecurity and to maintain surveillance systems that detect outbreaks early and enable veterinary services to respond rapidly.”[2]

Main recommendations from FAO and OIE included:

  • increase surveillance efforts for the early detection of avian influenza viruses
  • maintain and further strengthen rapid response capacities of veterinary services
  • reinforce biosecurity measures, with particular emphasis on minimizing contact between domestic poultry and wild birds
  • raise awareness of hunters and other individuals who may come into contact with wildlife in order to provide early information on sick or dead wild birds.

[1] Bui CM, Gardner L, MacIntyre CR. Highly pathogenic avian influenza virus, midwestern United States [letter]. Emerg Infect Dis. 2016 Jan [March 2016].

[2] World Poultry (2014, November). FAO:’Countries must do more to prevent avian influenza’. World Poultry, (2118), Retrieved from this website

By Pastor Alfonso, Researcher, CENSA, Cuba


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