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Chick-News.com Poultry Industry News, Comments and more by Simon M. Shane

Minnesota LPAI Deja Vu All Over Again?

11/30/2018

The toll in incident cases of H5N2 low pathogenicity strain avian influenza in two adjacent counties in Minnesota has reached 8 in five weeks. There appears to be an attitude of complacency given that the isolates involved are characterized as low-pathogenic strains. It is axiomatic that given sufficient time and a susceptible population of commercial poultry mutation to produce a highly pathogenic strain is inevitable. This is especially the case when virus can be disseminated by deficiencies in biosecurity. The shift from LPAI to HPAI has been demonstrated successively in outbreaks in Pennsylvania, Chile and Indiana.

The significant questions relating to the current cluster of cases should be addressed by aggressive and diligent epidemiologic evaluation. These include:-

  • Are the H5N2 isolates homologous?

  • From a molecular standpoint relating basic amino acids at the HA cleavage point, how likely is it that the H5N2 strain may become highly pathogenic?

  • What is the source of infection? If free-living birds, what species are involved, how long do they shed AI virus and the prevalence rate in these populations?

  • What is the connection among the affected farms in Kandiyohi and Stearns County? Commonality of ownership? Integrator? Service companies? Feed supplier?

  • Are any of the risk factors identified following the 2015 epornitic still present and contributing to infection? These include dead-bird and garbage collection? Unrestricted access to farms? Deficiencies in personal decontamination?

  • Are feed delivery vehicles and drivers subject to acceptable decontamination given that older flocks require more frequent deliveries increasing the probability of introduction of infection?

  • What is the role of multi-age placement? Three of the eight farms identified to date have two-age flocks common in Minnesota.

  • What are the risks of applying a "controlled slaughter" program with either an H5 or H7 low-pathogenicity infection? While it is generally accepted that turkeys will cease shedding within three weeks of infection, can quarantine be maintained during the viremic stage of infection especially with multi-age placement.

  • If other farms within the infected zone are free of infection, factors which contributed to introduction of virus onto affected farms should be evaluated. If farms which are in close proximity become infected, how is the virus transmitted? Air movement. Feed delivery? service personnel? State and Federal employees? Farm families? Farm workers?

    Now is the time for epidemiologic evaluation. It is possible that an understanding of both how the infection was introduced to farms in the two counties and how it has spread, presuming that each case is independent will be of help in advising the turkey industry in Minnesota to avoid a recurrence of 2015.

County

Date Diagnosed

Flock

Kandiyohi

October 19

13 Week Toms

Stearns

October 30

13 Week Hens

Stearns

November 5

2 Week Poults & 13 Week Hens

Kandiyohi

November 2

16 Week Toms

Stearns

November 3

8 Week Flock & 17 Week Hens

Stearns

November 3

6 Week Flock & 14 Week Toms

Kandiyohi

Kandiyohi

November 12

November 14

14 Week Toms

10 week toms


 
Copyright 2018 Simon M. Shane