Submitted to: United States Animal Health Association Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 10/26/2004
Publication Date: 1/31/2005
Citation: Spackman, E. 2005. 2004 outbreak of highly pathogenic h7n3 avian influenza in british columbia. United States Animal Health Association Proceedings. p. 563.
Technical Abstract: On February 19, 2004 avian influenza was detected on a commercial chicken breeder farm in British Columbia, Canada. The virus was characterized as an H7N3 subtype. Clinical signs on the index farm initially were mild drops in egg production and feed consumption and a minor increase in mortality. Gross lesions observed included lung lesions and inflamed tracheas. Within two weeks of the initial virus detection mortality in a second, younger flock on the index farm increased drastically. Characterization of the virus isolated from the first flock by NCFAD determined the virus to be low pathogenic avian influenza (LPAI) and the virus isolated from the second flock on the same farm was determined to be highly pathogenic avian influenza (HPAI). During late-March the number of infected commercial operations and back-yard flocks had increased to 20 and 6 respectively, and a pre-emptive slaughter of all poultry in the high-risk zone was ordered. On April 5th, all poultry in the larger "control area" were ordered to be depopulated, an estimated 19,000 birds. In mid-April a third group of farms were determined to be positive for the virus, all birds within a 3 Km radius of any infected farm were immediately depopulated. By May spread of the virus slowed and ended; the last positive commercial premise was identified on May 13th and the last positive back-yard flock was identified on May 18, 2004. By the end of the outbreak 42 infected commercial farms and 11 infected back yard flocks had been identified. Approximately 17 million birds were destroyed during the outbreak. Furthermore, during the outbreak two human cases of H7N3 influenza were confirmed in two individuals, who had extensive exposure to HPAI infected poultry. Mild symptoms including; conjunctivitis, runny nose, cough, headache and sore throat were reported by both individuals. Both patients were treated with the anti-flu drug Oseltamivir, and symptoms resolved in about a week.