First human case of H5 avian flu detected in B.C.
An individual in British Columbia (B.C.) has tested positive for avian influenza caused by the H5 influenza virus, marking the first detection of this virus in a person in B.C.
This case also represents the first presumed human infection with H5 avian influenza acquired in Canada. The positive test was conducted at the BC Centre for Disease Control’s Public Health Laboratory, and samples have been sent to the National Microbiology Laboratory in Winnipeg for confirmatory testing.
The individual is a teenager from the Fraser Health region who is currently receiving care at BC Children’s Hospital. The boy presented to the emergency room on 2 November with conjunctivitis, fever, and cough. On 8 November, the patient's status deteriorated and was admitted due to acute respiratory distress. Intravenous antivirals were administered.
A public health investigation has been initiated to determine the source of exposure and identify any contacts. The virus is clade 2.3.4.4b, genotype D1.1
Analyses conducted showed that the genome has an E627K mutation in the PB2 gene associated with mammalian adaptation and enhanced replication. This mutation has previously been observed in other human and mammalian infections. The HA gene also contained mixed bases, at positions 190 (E190D) and 226 (Q226H) (H3 numbering) in the mature HA protein. Mutations at these positions have been known to affect host specificity.
Since October 21, 2024, Canada has reported 21 cases of avian influenza (10 in October and 11 in November), with all cases except one occurring in poultry flocks in British Columbia. Prior to this, there had been no reports of the disease in Canada since April 2024.
Canada has not specified which genotype is involved in these incidents, other than to clarify that they are unrelated to the B3.13 genotype reported in US cattle.
To date, over 100 genotypes belonging to the 2.3.4.4b clade have been reported in North America, indicating the rapid evolution of the avian influenza virus in the region.
There is no evidence of infection with A(H5N1) in dairy cattle or viral detection in milk in Canada.
