A/H1N1 influenza, Canada

Information received on 05/05/2009 from Dr Brian Evans, Executive Vice President, Office of the President, Canadian Food Inspection Agency, OTTAWA, Canada

Summary

New outbreaks

Outbreak 1 (ALB-001)	Clearwater county, ALBERTA
Date of start of the outbreak	21/04/2009
Outbreak status	Resolved (29/07/2009)
Epidemiological unit	Farm
Affected animals	Species Susceptible Cases Deaths Destroyed Slaughtered Swine 3013 450 0 3013 0
Affected Population	Farrow/Finishing Operation: 220 sows and their piglets in two barns and 1,800 growers in four barns. Clinical signs (respiratory) were observed in the grower population followed by recovery over a 10-14 day period. Mortality slightly increased in the last few days in weanlings but at this point, it is not certain how much of this is attributable to A/H1N1 influenza virus infection.
Summary of outbreaks	Total outbreaks: 1
Outbreak statistics	Species Apparent morbidity rate Apparent mortality rate Apparent case fatality rate Proportion susceptible animals lost* Swine 14.94% 0.00% 0.00% 100.00% * Removed from the susceptible population through death, destruction and/or slaughter

Epidemiology

Source of the outbreak(s) or origin of infection

Possible transmission from humans to pigs.

Epidemiological comments

A carpenter hired by the farm owner (ALB-001) travelled to Mexico recently and returned to Canada on 12 April 2009. The carpenter, the producer and the producer's family had been ill with flu like symptoms between 14 – 29 April. Investigation of human cases by the Public Health authorities is underway. A Canadian Food Inspection Agency (CFIA) team attended the premises on 28 April and collected samples from swine for influenza virus testing. Swabs and serum samples were received at the CFIA National Centre for Foreign Animal Diseases (NCFAD) in Winnipeg on 29 April 2009. The samples were run in conventional RT-PCR for the Matrix and the H1 gene (primers kindly provided by the PHAC National Microbiology Laboratory, Winnipeg). These results showed that 19/24 samples were positive for the M gene and 15/24 samples positive for the H1 gene. This was immediately followed up by sequencing of these PCR products (6 samples for the Matrix and 5 for the H1 gene). The sequences of a segment of approximately 244 nucleotides of the Matrix gene from 6 samples showed that this sequence was 100% (for the 244 nucleotides sequenced) identical to sequences derived from the novel A/H1N1 influenza virus from the USA and Mexico and similar results (99-100% identity) were found for around 500 nucleotides of the H1 gene from 5 samples. The sequences derived from the pig samples were identical to each other and for the M gene most similar to the Eurasian lineage while the H1 gene is more reminiscent of the North American lineage as would be expected for this novel virus. Additional sequencing of part of the N gene clearly shows that this is a N1 virus and the sequence of the approximately 1,400 nucleotide fragment is highly related to the novel A/H1N1 influenza virus. It is thus confirmed that this is the novel A/H1N1 influenza virus and being very closely related to the human strains based on the genes sequenced so far. Full characterisation is continuing and so is virus isolation in eggs.

Control measures

Measures applied	Quarantine No vaccination No treatment of affected animals
Measures to be applied	No other measures

Diagnostic test results

Laboratory name and type	CFIA National Centre for Foreign Animal Diseases - Winnipeg (National laboratory)
Tests and results	Species Test Test date Result Swine gene sequencing 04/05/2009 Positive Swine polymerase chain reaction (PCR) 01/05/2009 Positive

Future Reporting

The event is continuing. Weekly follow-up reports will be submitted.

Map of outbreak locations

Location of current outbreaks

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