Avian Influenza Reassortment Raises Spillover Risk

New H5N1 lineages in South and Southeast Asia are reshaping zoonotic risk, with experts warning of renewed human infections.

Emerging Lineages Heighten Human Risk

South and Southeast Asia: Avian influenza is once again making headlines in Asia, as scientists detect the new H5N1 strains across poultry farms in South and Southeast Asia. Unlike simple mutations, reassortment occurs when different influenza viruses exchange genetic material, creating novel lineages with unpredictable behaviour. This development has raised alarm among virologists who note that human infections, once rare, are beginning to reappear after years of relative stability.

Why Is This Happening Now?

Experts point to intensive poultry farming, live bird markets, and cross-border trade as key drivers of viral mixing. “We are seeing genetic reshuffling that increases the likelihood of spillover into humans,” said Dr. Nguyen Van Long, a regional influenza specialist. WHO has urged countries to strengthen genomic surveillance and biosecurity measures, warning that gaps in monitoring could allow dangerous strains to spread undetected.

What Does This Mean for Public Health?

The resurgence of avian influenza highlights Asia’s vulnerability to zoonotic diseases. Poultry-dependent economies face both economic and health risks, as culling campaigns threaten livelihoods while hospitals prepare for potential clusters of human cases. Regional cooperation is being emphasised, with calls for shared data platforms and coordinated vaccination strategies for poultry.

While no sustained human-to-human transmission has been confirmed, experts caution that reassortment events increase the probability of pandemic potential. Governments are urged to integrate influenza monitoring into broader pandemic preparedness frameworks.

Source: WHO Asia-Pacific Influenza Surveillance Report, October 2026.