Wednesday January 1, 2025 | VICTORIA, BC [Posted at 3 pm | Last update: January 2, 2025]
by Mary P Brooke, B.Sc. | Island Social Trends
The H5N1 case that Provincial Health Officer Dr Bonnie Henry announced to media on November 9 (with an update on November 26) has been written up in a December 31, 2024 journal article (posted letter) in the New England Journal of Medicine.
The online posting says that the findings and conclusions itemized in the report are those of the 19 authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention.
It is now known that the infected person is a 13-year-old girl who was infected.
The age and gender of the patient was not previously released by Dr Henry or the BC CDC. Dr Henry told media on November 26 that the patient was still in critical condition and was not breathing on her own. On November 26 Dr Henry said there would be no more updates.
Background on the virus:
Highly pathogenic avian influenza A(H5N1) viruses are circulating among wild birds and poultry in British Columbia, Canada and in the USA. These viruses are also recognized to cause illness in humans.
The BC Centre for Disease Control (BC CDC) says avian flu is a contagious viral infection.
The BC authors in their article reported the one BC case of critical illness as caused by influenza A(H5N1) virus infection.
This was the first H5N1 case in Canada. There have been no other reported H5N1 cases in BC since this singular incident.
Reportedly the genetics of the H5N1 virus that was detected had mutated three times, which increases the possibility for greater transmissibility to humans.
The more cases reported in a province, the greater the likelihood of retail prices for poultry and eggs being affected. [See Latest Bird Flu Situation – Canadian Food Inspection Agency]
Teenage girl presented with conjunctivitis and fever:
“On November 4, 2024, a 13-year-old girl with a history of mild asthma and an elevated body-mass index (the weight in kilograms divided by the square of the height in meters) of greater than 35 presented to an emergency department in British Columbia with a 2-day history of conjunctivitis in both eyes and a 1-day history of fever,” the authors wrote.
The patient was at first discharged home without treatment but cough, vomiting, and diarrhea then developed.
- “She returned to the emergency department on November 7 in respiratory distress with hemodynamic instability,” the article stated. Hemodynamic instability is abnormal or unstable blood pressure, which can cause inadequate blood flow to body organs. Symptoms may include abnormal heart rate (arrhythmias) and chest pain.
- On November 8, the girl was transferred (while receiving bilevel positive airway pressure) to the pediatric intensive care unit at British Columbia Children’s Hospital. She had respiratory failure, pneumonia in the left lower lobe, acute kidney injury, thrombocytopenia, and leukopenia.
- The patient had signs of respiratory deterioration — chest radiographs were consistent with progression to acute respiratory distress syndrome — which prompted tracheal intubation and initiation of venovenous extracorporeal membrane oxygenation (ECMO) on November 9.
- On December 18 she no longer needed oxgyen support.
- The teen is still in hospital but is out of intensive care.
Influenza A and high viral load was first detected:
A nasopharyngeal swab obtained at admission had been positive for influenza A but negative for A(H1) and A(H3) by the BioFire Respiratory Panel 2.1 assay (BioFire Diagnostics). Reflex testing of the specimen with the Xpert Xpress CoV-2/Flu/RSV plus assay (Cepheid) revealed an influenza A cycle threshold (Ct) value of 27.1.
A reverse-transcriptase–polymerase-chain-reaction (RT-PCR) test specific for influenza A(H5) was positive on the day of admission.
This finding indicated a relatively high viral load for which subtyping would be expected; the lack of subtype identification suggested infection with a novel influenza A virus.
Treatment:
Oseltamivir treatment was started on November 8 and the use of eye protection, N95 respirators, and other precautions against droplet, contact, and airborne transmission were implemented.
Continuous renal replacement therapy was initiated on November 10. Combination antiviral treatment with amantadine (initiated on November 9) and baloxavir (initiated on November 11) was added to ongoing treatment with oseltamivir. Bacterial cultures of blood (samples obtained at admission) and endotracheal aspirate (obtained after intubation) yielded no growth.
Because of concern for cytokine-mediated hemodynamic instability, plasma exchange was performed daily from November 14 through November 16.
“Serial influenza A–specific RT-PCR tests showed increasing Ct values, which suggested a decline in the viral RNA load in serum and a decline in viral RNA in upper- and lower-respiratory specimens shortly after the initiation of antiviral treatment, with the first negative RT-PCR result for serum obtained on November 16,” as stated in the journal article.
“It is notable that lower-respiratory specimens consistently yielded lower Ct values than upper-respiratory specimens, a finding that suggested higher viral levels in the lower-respiratory tract,” as stated in the journal article.
===== RELATED:
- Dr Henry delivers H5N1 avian flu update (November 26, 2024)
- First human case of H5N1 avian flu in Canada detected in BC teen (November 9, 2024)
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