The world’s first human H5N5 bird flu death has been reported in Washington. While the virus poses low human risk, it remains a significant ecological and agricultural threat. No human-to-human transmission is detected, but scientists urge vigilant surveillance and One Health–based monitoring to prevent future spillover events.
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The United States has reported the world’s first human infection and death caused by the H5N5 avian influenza virus.
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Must Read: AVIAN INFLUENZA VIRUS (H9N2) | BIRD FLU | H5N1 avian influenza | H5N2 BIRD FLU | |
H5N5 is a subtype of the Influenza A virus, a large viral family that naturally circulates among wild birds and periodically spills over into domestic poultry and, rarely, humans. Conceptually, H5N5 represents one of many evolutionary possibilities within avian influenza viruses, which continuously mutate and reassort their genetic segments.
Part of a Continuum of Avian Influenza Diversity: Influenza A viruses are categorized based on combinations of two surface proteins
Avian influenza evolves through Antigenic drift (small mutations) and Antigenic shift (exchange of gene segments across viruses).
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Feature |
H5N1 |
H5N5 |
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Evolutionary Exposure to Humans |
Repeated spillovers over two decades |
Human exposure extremely rare |
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Global Ecological Footprint |
Wide presence in birds, mammals, poultry; well-established lineage |
Detected mainly in wild birds; limited spread to poultry |
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Disease Expression in Humans |
Known to cause severe disease; high fatality in reported cases |
Not well understood; first-ever human infection in 2025 |
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Opportunity for Adaptation |
High – repeated mammalian infections give more chances to evolve |
Low – minimal human or mammalian contact limits adaptation |
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Monitoring Priority |
High priority due to historical pandemic concern |
Lower but increasing due to first human case |
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Public Health Risk Dynamics |
Recognized zoonotic threat with documented cross-species adaptation |
Emerging concern, but currently seen as a rare spillover |
Zoonotic spillovers are Increasing: Over the past two decades, spillover events of avian influenza into humans have accelerated, reflecting changing patterns of human–animal–environment interactions. China recorded over 1,500 human cases of H7N9 during 2013–2017.
Influenza A viruses mutate and reassort rapidly: Avian influenza viruses have segmented genomes, meaning they can exchange genetic material when two strains infect the same host. This gives them exceptional evolutionary flexibility. Influenza A can mutate up to 300x faster than many DNA viruses.
Influenza has a deep pandemic history
While most avian influenza infections in humans are one-off events, influenza is historically the most successful human pandemic virus.
History
Each of these pandemics involved reassortment between avian and mammalian influenza viruses.
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How influenza outbreaks impact constitutional provisions in India? Public Health as a State Subject · State List, Entry 6: Public health and sanitation; hospitals and dispensaries · State List, Entry 8: Pest control, animal husbandry (relevant for avian influenza) Influenza outbreaks overwhelm state systems and often exceed state capacity. Centre–State coordination under the concurrent list · Entry 23: Social security and social insurance · Entry 29: Prevention of extension from one State to another of infectious or contagious diseases. Influenza outbreaks activate Entry 29, enabling the Centre to frame regulations to prevent interstate spread of disease. Article 19(1) – Freedom of movement, trade, assembly Can be reasonably restricted under Art. 19(5) in the interest of public health. |
Integrated Disease Surveillance Programme (IDSP)
Indian Council of Medical Research – Virus Research & Diagnostic Laboratory (VRDL) Network (Virus Research & Diagnostic Laboratories)
National Influenza Surveillance Programme (NISP)
National Action Plan for Prevention, Control & Containment of Avian Influenza (NAP-AI) (Released by Department of Animal Husbandry & Dairying)
Core components:
NADRS 2.0 (National Animal Disease Reporting System)
National Centre for Disease Control (NCDC)
The first H5N5 human death is a tragic but isolated spillover event. While immediate human risk is low, the episode underlines the importance of vigilant surveillance, genomic monitoring, and One Health preparedness to prevent future zoonotic threats.
Source: Down to earth
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Practice Question Q. Avian influenza strains such as H5N1 and H5N5 pose a recurring zoonotic threat. Discuss (150 words) |
Because public health is primarily a state subject, but infectious diseases can spread across districts and states. This triggers the Concurrent List (Entry 29) and the Union List (Entry 28), enabling the Central Government to coordinate surveillance, quarantine, and interstate disease control.
They mutate rapidly, frequently reassort with other influenza strains, and occasionally cross species barriers. Although most spillovers do not sustain transmission, the viral family has a historic capacity to generate pandemics (1918, 1957, 1968, 2009).
Not currently. No sustained human-to-human transmission has been detected. A pandemic requires a virus that spreads efficiently among humans, which avian viruses have not yet achieved.
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