the existing deficits and necessary preventive measures, but a period of five years with little epidemic incidence were obvi- ously enough to feel safe. The fact that the 2015 epidemic was regarded as a singular event certainly contributed to this.
Two flight corridors When looking at the spatial pattern of the 2022 epidemic in context it becomes obvious that, in contrast to 2015 (Wind- horst 2015), it was not only the ‘Mississippi flight corridor’ of wild birds that led to the primary outbreaks, but that primary infections also occurred in the Atlantic corridor which caused several epicenters of outbreaks (National Wildlife Health Center 2022). Although APHIS informed farmers in February 2022 of the emerging high risk of infection after wild birds were found in the north of the two corridors that had died from the virus strain (which was probably imported from northern Europe and northern Asia). When the first outbreaks occurred in early February, necessary measures were appar- ently initiated only reluctantly. In view of the high infection pressure from wild birds, the first outbreaks in turkey flocks, the high susceptibility of turkeys to the AI virus and the pre- vailing forms of housing (open barns) in the northern Mid- west, it was almost impossible to prevent the virus from spreading. What is surprising though was the renewed out- breaks in the same large layer farms in Iowa that had been af- fected in 2015. Here, the management had apparently not succeeded in improving biosecurity such that the virus could be prevented from entering. The epidemic of 2022 with more than 40 million animal losses and economic damage of again US$ 2.5 to 3 billion should result in even closer wild bird mon- itoring in the north of the three major flight corridors in fu- ture to assess the risk of entry at an early stage. Apparently, educating farmers about the need for biosecurity on their farms was again not sufficient. A repetition of the situation in 2015 was considered unlikely, leading to a false sense of
14 ▶ POULTRY WORLD | No. 6, 2022
security as soon became apparent. Turkey farmers could con- sider switching to closed barns also to reduce the risk of en- try. An Iowa company, which again lost over 5 million laying hens and had to stop egg processing, has announced that it plans to decentralise its farm complex and separate primary production and processing.
References available on request.
Table 2 – The states mainly affected by the Avian Influenza outbreaks in 2022.
State Iowa Nebraska
Pennsylvania Colorado Wisconsin Minnesota Maryland
South Dakota Utah
Delaware
North Carolina Missouri Kentucky Indiana
North Dakota Michigan Oklahoma 17 states USA total
Source: USDA APHIS 2022 Outbreaks
15 4
17 4 8
59 4
36 1 3 9 6 2 9 4 1 1
183 186
Lost birds x 1,000
13,374.2 4,853.6 4,224.7 3,556.1 3,027.7 2,964.0 1,762.1 1,666.2 1,501.3 1,438.6 481.4 434.8 284.7 189.6 167.0 36.0 13.8
39,975.8 40,088.6
Share (%) 33.4 12.1 10.5 8.9 7.6 7.4 4.4 4.1 3.7 3.6 1.2 1.1 0.7 0.5 0.4 0.1
< 0.1 99.7
100.0
From mid- March, several large layer flocks in Iowa and Wis- consin were af- fected by avian influenza.
PHOTO: ANP
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