Teenager hospitalised with bird flu

Authorities are investigating whether the case in Canada is linked to the H5N1 outbreak in US dairy herds

A teenager has been hospitalised with bird flu in Canada, in the first suspected case to be found in the country.
Officials said the patient likely caught the H5 virus from a bird or animal, but are investigating the source of the infection and tracing potential contacts.
“This is a rare event,” Dr Bonnie Henry, the British Columbia (BC) health officer, said in a statement. 
“While it is the first detected case of H5 in a person in BC or Canada, there have been a small number of human cases in the US and elsewhere, which is why we are conducting a thorough investigation to fully understand the source of exposure.”
Across the globe 903 cases of H5N1 have been detected in humans since 2003, according to the World Health Organisation, including 464 fatal infections.
But this year, there have been mounting concerns that the US is struggling to contain an epidemic of H5N1 in cattle, which is increasingly spilling into humans. The pathogen has been detected in nearly 450 dairy farms across 15 states since March, and 46 people have also contracted the virus.
This figure is likely to be a significant underestimate. Last week, a US Centre for Disease Control and Prevention study found 7 per cent of 115 farm workers exposed to infected cattle had evidence of prior infection, but that only half remembered having symptoms – prompting calls for all farm workers in contact with infected animals to be screened for H5.
Although the symptoms have generally been mild amongst those infected in the US, the high case count is concerning experts because it provides many more opportunities for the virus to evolve to better infect people. This fear was only amplified when H5N1 was recently detected in pigs for the first time.
The source of the H1N1 pandemic – also known as ‘swine flu’ – pigs have also been implicated as the source of other influenza outbreaks, and are described as being a “mixing vessel” for the pathogen. This is because they have receptors for both avian and human flu viruses, allowing them to be infected by strains from different species at the same time.
When this happens, the viruses can exchange genetic material in a process known as “reassortment” which can make it more likely that the virus could adapt to spread between humans.
It is not yet clear whether the Canadian teenager’s suspected infection (authorities are awaiting secondary confirmation) could be linked to the outbreak in the US, but health officials have urged for the potential to be investigated.
“Very concerning news about this case of H5 avian flu in a teenager in Canada,” Dr Krutika Kuppalli, a spokeswoman for the Infectious Disease Society of America and former WHO medical officer, wrote on X.
She added that the next steps include investigating patient exposures, treating the teenager to “conduct genomic sequencing to check any link to the H5N1 outbreak in US dairy herds”.
In May, Canada tightened import requirements on American breeding cattle amid concerns about the outbreak there, and the country found no trace of H5N1 when it sampled commercial milk supplies.
Dr Rick Bright, a former head of the US Biomedical Advanced Research and Development Authority, said it was important to follow the latest case in Canada closely, as a “hospitalised teenager is a serious outcome”.
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