A letter sent to the editor of The New England Journal of Medicine signed by Canadian health officials says the British Columbia teenager who tested positive for avian flu has been taken off supplemental oxygen and is no longer infectious.
The letter, which was published Tuesday and provides a summary and timeline of the case, was signed by doctors from the B.C. Centre for Disease Control, B.C. Children’s Hospital, the Public Health Agency of Canada, and B.C.’s agriculture ministry.
It says the patient was a 13-year-old girl who went to a B.C. emergency room on Nov. 4 with a fever and conjunctivitis in her eyes.
The teen, who is described as having a history of mild asthma and an elevated body mass index, was initially discharged without treatment, but developed a cough, vomiting and diarrhea before she returned on Nov. 7 in respiratory distress.
The report says the girl was transferred the next day to the pediatric intensive care unit at British Columbia Children’s Hospital for treatment, which included temporary tracheal intubation.
B.C.’s top doctor says they still don’t know how a teenager became sick with a strain of avian flu. The update comes as another case has been identified in a child in California. As Michelle Ghoussoub reports, officials stress the risk of transmission to humans remains low.
Additional information posted to the journal’s website says the patient was deemed no longer infectious on Nov. 29 and no longer required supplemental oxygen as of Dec. 18.
It also indicates both the girl and her family consented to releasing additional details on her case and notes that, to date, the source of her H5N1 exposure has not yet been determined.
It says there have been no secondary cases of transmission of the virus in the girl’s home or at the hospital.
The teen’s infection, which was announced in November, was the first human case of H5N1 avian flu acquired in Canada. The Ministry of Health had said the teen is from the Fraser Health region, which includes several of Vancouver’s eastern and southern suburbs and the Fraser Valley.
B.C.’s commercial poultry sector has been damaged by avian flu outbreaks in recent years. The most recent data posted to the Canadian Food Inspection Agency website says more than 8.5 million birds have been “impacted” in the province since the spring of 2022.
Most of the outbreaks reported in recent months in the province have been in the Fraser Valley, located within the Fraser Health region.
Dr. Maria Van Kerkhove, the World Health Organization’s director of epidemic and pandemic preparedness, is calling for increased surveillance globally of animal populations that are known to be susceptible to H5N1, including wild birds, poultry, swine and cattle.
The investigation of the case of the teenager in B.C. with H5 avian flu included testing of pets, birds and other animals from nearby premises as well as environmental testing of soil and water, according to the province.
It determined that the strain the teen contracted closely matches the strain found in wild birds in the Fraser Valley area in October and was not directly related to outbreaks at poultry farms in B.C.
‘A terrible virus’
The letter sent to The New England Journal of Medicine says that the H5N1 virus can cause severe human illness.
“Evidence for changes to [protein structures] that may increase binding to human airway receptors is worrisome,” the letter concludes.
A housecat has died in the United States after eating raw pet food and contracting H5N1 bird flu. Epidemiologist Dr. Christopher Labos tells CBC News the risk of any individual pet getting avian flu is still low, but what is concerning is the easier it becomes for it to infect different types of animals, ‘the easier it will ultimately become for this virus to infect humans.’
Dr. Isaac Bogoch, an infectious disease specialist at Toronto General Hospital, said the letter and the symptoms it talked about were consistent with other reports on human cases of avian influenza over the past two decades.
“If you look at how severe this infection was, I think it’s pretty fair to say that this is a terrible virus,” he told CBC News.
“And also, for lack of a better word, a very vigorous host response and significant inflammatory response to this virus.”
Bogoch said the virus wasn’t yet being readily transmitted from human to human, but urged authorities to take precautions.
“We really have to ensure that there’s as few mammals as possible infected with this virus,” he said. “So we don’t give it opportunities to mutate in a way that it is more readily transmitted between humans.”