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Tuesday, Nov 25, 2025
Outside the box.
Rare H5N5 Avian Flu Strain Claims First Known Human Life in Washington State
Older adult in Grays Harbor County dies after backyard poultry exposure; no evidence of human-to-human transmission
A resident of Grays Harbor County, Washington has died after contracting the H5N5 strain of avian influenza, marking the first confirmed human fatality globally from this variant, state health officials announced.
The individual, described as an older adult with underlying health conditions, maintained a mixed backyard flock of domestic poultry which likely interacted with wild birds.
Diagnostic testing by the University of Washington Clinical Virology Lab and confirmation from the U.S. Centers for Disease Control and Prevention established that the deceased person had been infected with H5N5, a strain previously documented only in animals.
Environmental samples from the backyard property detected the virus in the bird-flock environment, suggesting exposure via domestic poultry or wild-bird contact as the likely transmission route.
Health authorities emphasised that the risk to the wider public remains low.
No other individuals connected to the case — including household contacts or more than one hundred healthcare workers — have tested positive for the virus, and there is no evidence of human-to-human transmission at this time.
The Washington State Department of Health and federal partners are monitoring close contacts for symptoms and conducting follow-up testing.
Officials urged backyard poultry owners and those in contact with wild birds to follow precautionary measures, including reporting sick or dead birds, avoiding direct contact with wild-bird carcasses, and ensuring that household members receive their seasonal influenza vaccination.
While the influenza vaccine does not protect directly against avian strains, it reduces the risk of dual infection with human and avian influenza, which could facilitate viral reassortment.
The case highlights a previously unseen zoonotic transmission event of H5N5 into a human, prompting heightened surveillance of avian-influenza activity in poultry, wild birds and humans alike.
Public-health agencies emphasise that the situation remains stable but continue to treat it as a significant alert given the virus’s novel human presentation.
The individual, described as an older adult with underlying health conditions, maintained a mixed backyard flock of domestic poultry which likely interacted with wild birds.
Diagnostic testing by the University of Washington Clinical Virology Lab and confirmation from the U.S. Centers for Disease Control and Prevention established that the deceased person had been infected with H5N5, a strain previously documented only in animals.
Environmental samples from the backyard property detected the virus in the bird-flock environment, suggesting exposure via domestic poultry or wild-bird contact as the likely transmission route.
Health authorities emphasised that the risk to the wider public remains low.
No other individuals connected to the case — including household contacts or more than one hundred healthcare workers — have tested positive for the virus, and there is no evidence of human-to-human transmission at this time.
The Washington State Department of Health and federal partners are monitoring close contacts for symptoms and conducting follow-up testing.
Officials urged backyard poultry owners and those in contact with wild birds to follow precautionary measures, including reporting sick or dead birds, avoiding direct contact with wild-bird carcasses, and ensuring that household members receive their seasonal influenza vaccination.
While the influenza vaccine does not protect directly against avian strains, it reduces the risk of dual infection with human and avian influenza, which could facilitate viral reassortment.
The case highlights a previously unseen zoonotic transmission event of H5N5 into a human, prompting heightened surveillance of avian-influenza activity in poultry, wild birds and humans alike.
Public-health agencies emphasise that the situation remains stable but continue to treat it as a significant alert given the virus’s novel human presentation.
