Diagnostic test results and pathology associated with the 2007 Canadian H7N3 highly pathogenic avian influenza outbreak.
In September 2007, an H7N3 highly pathogenic avian influenza outbreak (HPAI) occurred on a multiple-age broiler breeder operation near Regina Beach, Saskatchewan, Canada. Mortality was initially observed in a barn that housed 24-wk-old roosters, with later involvement of 32-wk-old breeders. All birds on the affected premises were destroyed, and surveillance of surrounding farms demonstrated no further spread. The use of water from a dugout pond during periods of high demand, and the proximity of the farm to Last Mountain Lake, the northern end of which is a bird sanctuary, implicated wild aquatic birds as a possible source of the virus. Of particular note, the H7-specific real-time reverse transcription polymerase chain reaction assay that was in use at the time did not detect the virus associated with this outbreak. A Canadian national influenza A virus survey of wild aquatic birds detected no H7 subtype viruses in 2005 and 2006; however, H7 subtype viruses were detected in the fall of 2007. Phylogenetic analysis of a number of these H7 isolates demonstrated an evolutionary relationship with each other, as well as with the H7N3 HPAI virus that was isolated from the Saskatchewan broiler breeder farm.
National Centre for Foreign Animal Disease, Canadian Food Inspection Agency, Winnipeg, Manitoba R3E 3M4, Canada. jpasick@inspection.gc.ca
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J
Pasick
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Berhane
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Hisanaga
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Kehler
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Hooper-McGrevy
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Handel
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Neufeld
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Argue
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Leighton
D000818:Animals; D002170:Canada / Q000453:epidemiology; D002645:Chickens; D004196:Disease Outbreaks / Q000662:veterinary*; D009980:Influenza A virus / Q000145:classification* / Q000235:genetics / Q000472:pathogenicity*; D005585:Influenza in Birds / Q000453:epidemiology* / Q000821:virology; D010802:Phylogeny