What you need to know
- A Louisiana person has died from H5N1 bird flu, though they were in an at-risk age group and had underlying health conditions.
- 66 people in the US have contracted the strain of bird flu from exposure to animals.
- No human-to-human transmission has been detected, US health officials say disease “remains a low risk” to the public.
A Louisiana patient hospitalized with H5N1 bird flu has died, marking the first human fatality in the linked to the disease.
However, health officials have stressed the risk to the wider US population remains low.
The Louisiana Department of Health said in a press statement that the patient contracted the disease through exposure to backyard flocks and wild birds.
The patient was also part of a high-risk group, as they were aged over 65 and had an underlying health condition.
“While the current public health risk for the general public remains low, people who work with birds, poultry or cows, or have recreation exposure to them, are at higher risk,” officials said in the statement.
The deceased person was hospitalized on December 18 and was the only confirmed case of H5N1 in that state. It also remains the only severe US case admitted to hospital.
In total, 66 people in the US have contracted H5N1 during the current outbreak. The first case was reported in April 2024.
So far all confirmed cases have been . No cases of human-to-human transmission have been reported.
The US Centers for Disease Control and Prevention (CDC) continues to monitor the spread of the disease in livestock and poultry flocks.
The CDC said in a statement that death from H5N1 was “not unexpected because of the known potential for infection with these viruses to cause severe illness and death.”
How deadly is H5N1 for humans?
H5N1 was first identified during an outbreak in in 1996.
Globally, around 900 people have been infected with bird flu between 2003 and 2024 according to the World Health Organization (WHO).
There have been several outbreaks of the disease which involved human transmission: Vietnam (89 cases, 2004-2005); Indonesia (159 cases, 2005-2009), and Egypt (346 cases, 2006-2015).
Across 24 countries that have reported H5N1 cases since 1998, around 1 in 2 cases resulted in death.
However, the fatality rate in the US is currently one in 66 cases, raising questions about how deadly H5N1 infections are.
Marrazzo and Ison say that the reasons for lower fatality rates in the North America are not currently clear.
“Low risk to the general public”
While monitoring continues, the US National Institute of Allergy and Infectious Diseases (NIAID) officials have emphasized the low risk posed to most Americans by the disease.
Writing in the New England Journal of Medicine, NIAID’s director Jeanne Marrazzo and chief of respiratory diseases Michael Ison highlighted the availability of “candidate” vaccines.
Candidate vaccines enable drug makers to mass produce H5N1 vaccines for the public, which would “mitigate severe influenza in the case of wider spread”.
A using technology from Moderna was recently conducted in ferrets.
Severe infection can lead to pneumonia, respiratory failure or distress, kidney injury and septic shock, according to the CDC.
US health authorities are advising people to avoid exposure to sick or dead animals and to use personal protective equipment when exposed to sick or dead poultry including wild and domesticated animals and feces.
British Columbia case highlights need for mutation monitoring
Despite the death now reported in Louisiana, no other people infected with H5N1 have been hospitalized with severe illness.
However the case of a Canadian teenager who was hospitalized with respiratory failure remains a cause for concern. The teenager has since recovered, but an assessment of her infection found key genetic mutations that are believed to be associated with enhanced virulence and human adaptation.
An earlier study found a single, specific mutation to the genetic code of the variant currently circulating in US dairy cattle would be sufficient to enhance its ability to infect human cells.
It’s not known how the teenager contracted the infection and poor-quality data collection was flagged by Marrazzo and Ison as a key challenge that needs to be overcome.
While current risk to humans may remain low, .
However, the pandemic potential of the disease means monitoring efforts need to be increased. Two pandemics have been declared in the past 16 years (COVID in 2019 and H1N1 swine flu in 2009).
Concerns that H5N1 variants may mutate to cause more severe illness or become more transmissible are high following the COVID-19 pandemic, which caused billions of infections and millions of deaths worldwide.
Edited by: Fred Schwaller
Sources:
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