Scientists at the ICMR-National Institute of Virology (NIV) published their recent findings on the origins and genetic evolution of avian Influenza virus, isolated from recent outbreaks in India. In their recent findings published in Virology (Elsevier), scientists have shown that the strains of avian influenza / bird flu seen in Kerala in 2024 are likely of East Asian origin.
Key Findings
- Origin & Timing of Introduction
- The virus strain H5N1 detected in Kerala in June 2024 is described as a novel re-assortment — meaning it acquired genetic segments from different parent virus strains. Some internal genes appear to derive from earlier low pathogenic avian influenza (LPAI) viruses seen in Kerala; others are of European origin.
- NIV’s molecular clock and phylogeographic analysis suggest that this H5N1 strain entered India from East Asia around 2022.
- Previous Outbreaks’ Links
- Earlier H5N8 outbreaks in 2016 in India (e.g. in zoological parks in Delhi and Madhya Pradesh) were also traced back to separate introductions from East Asia (China and Japan) around 2015.
- Migration, Mix & Re-Assortment
- The study highlights how migratory birds play a role. India lies on the Central Asian flyway, which means wild birds can carry viruses long distances, acting as “bridges” for virus spread.
- Once introduced, local reassortment (mixing of genetic material among bird flu strains) has occurred, creating new combinations (variants) that might have altered properties — transmissibility, pathogenicity, or host range.
- Vulnerable Zones & Ecosystems
- Kerala is flagged as particularly vulnerable due to its ecology: lakes, backwaters, high density of poultry and duck populations. These settings provide ample opportunity for wild/domestic bird interactions, increasing chances of spillover and reassortment.
- Gaps in Surveillance & Data
- The study notes that India has relatively limited genetic data from bird flu outbreaks compared to other regions. This makes it more difficult to detect emerging variants early or to fully map transmission routes.
- Calls are being made for stronger molecular surveillance, more frequent sequencing, and better monitoring of virus introductions (especially via migratory birds), to anticipate risk.
Implications
- Public Health & Zoonotic Risk: While bird flu primarily affects avian species, H5Nx viruses (H5N1, H5N8 etc.) are considered to have zoonotic potential, meaning under certain conditions they could infect mammals, including humans. Novel reassortants raise the concern of changing virus properties. Early detection matters.
- Poultry Industry: Frequent outbreaks affect poultry health and economics. Better tracing and surveillance could help prevent or limit outbreaks, which means fewer losses, fewer culls, and less disruption to supply chains.
- Wildlife & Ecology: Ecological changes that affect migratory bird patterns (e.g. climate change, habitat loss) might increase risks. Regions like Kerala, where wild and domestic birds interact heavily, are hotspots that require monitoring.
- Policy & Preparedness: The findings suggest that India should invest more in wildlife surveillance, genomic sequencing, information sharing, and early warning systems. There may also be a need for border/biosecurity protocols around migratory flyways and bird trade.
