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Peer reviewedOpen accessH5N1Influenza

Transmission, Pathological and Clinical Manifestations of Highly Pathogenic Avian Influenza A Virus in Mammals with Emphasis on H5N1 Clade 2.3.4.4b.

Viruses·

Larsen SV, Israelson R, Torp C, Larsen LE, Jensen HE, Kristensen C

DOI
10.3390/v17121548
PMID
41472219
PMCID
PMC12737373
OpenAlex
W4416718528
Study type
Journal article
Publisher
Publisher unavailable
Article type
journal-article
Integrity
current

Why this research matters now

The demonstrated capacity for cross-species infection and potential intermammalian transmission highlights ongoing risks for human exposure and reinforces the importance of systematic monitoring to track viral evolution in animal reservoirs.

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Structured evidence summary

Research question

This review investigates the transmission patterns, disease pathology, and clinical symptoms associated with highly pathogenic avian influenza A virus H5N1 clade 2.3.4.4b in mammalian hosts, with particular attention to central nervous system involvement.

Study design

The authors performed a narrative review that synthesized previously documented case reports to characterize infection patterns across distinct mammalian categories.

Population and setting

The analysis focuses on naturally infected terrestrial wildlife, marine species, and dairy cattle, with documented cross-species spillover events concentrated in European and American regions.

Main findings

Clinical presentations vary by host group, showing respiratory and neurological symptoms in marine animals alongside lethargy and neurological deficits in land-dwelling species. Tissue damage predominantly targets the lungs and brain in wildlife, whereas gastrointestinal and mammary structures are primarily affected in livestock. Elevated viral concentrations within neural tissue highlight a strong neurological preference, while emerging observations suggest possible direct animal-to-animal and parent-to-offspring spread.

Public-health relevance

The demonstrated capacity for cross-species infection and potential intermammalian transmission highlights ongoing risks for human exposure and reinforces the importance of systematic monitoring to track viral evolution in animal reservoirs.

Important limitations

The precise biological mechanisms enabling central nervous system entry remain unverified, with several theoretical pathways still under discussion. Furthermore, the conclusions rely entirely on compiled observational reports rather than controlled experimental investigations.

GIDS interpretation

This publication situates cross-species viral ecology within broader One Health frameworks by cataloging host-specific disease signatures and highlighting the scientific value of coordinated tracking systems for emerging infectious agents.

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Related GIDS surveillance

Literature context does not validate, explain, or change a surveillance signal. Exact and contextual relationships are shown separately.

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Evidence relationships

This article has 9 auditable classifier relationships to diseases, places, topics, and study design.

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