Why Environmental Surveillance for Avian Influenza is Essential

Missing: There is no active surveillance of poultry birds for avian influenza virus in India.

The world’s largest colony of northern boobies on Bass Rock, an island off the coast of North Berwick in Scotland, was recently devastated by bird flu (H5N1), or bird flu. H5N1 has caused unprecedented losses of tens of thousands of birds in the UK Annual gatherings at breeding grounds indicate that the highly pathogenic her H5N1 has ripped apart bird colonies and left many carcasses on beaches and outlying islands. Left, it quickly turned into a super spread event.

The impact of this disease is very serious for bird conservationists. From an epidemiological point of view, transmission from dead birds to carnivores such as sea lions, foxes and seagulls poses a serious risk. Recently, intramammal transmission of his H5N1 on a captive mink farm was documented, raising greater concerns regarding the potential for zoonotic disease.

In India, the latest major bird flu outbreak in 2020-2021 swept many states and caused mass mortality of wild birds. This has raised concerns at the forefront of the lack of active monitoring and how wetlands and waterfowl habitats in contact with poultry need to be protected. . Monitored. India is a major wintering ground for many waterbirds that depend on the Central Asian flyway.

Although outbreaks of avian influenza coincide with peak seasons for migratory birds leading to post-outbreak surveillance and culling, there are also reports of off-season outbreaks suggesting endemic transmission within the poultry sector. India has the fastest growing egg production in the world, but unlike Europe, poultry here are not vaccinated against influenza. In addition, farms with diverse animals or near nearby wetlands are more likely to reassort the virus, producing more virulent strains such as H5N1 and H7N9 that can infect humans. I have.

Despite this potential, there is no active surveillance in the poultry sector. We may not yet have an efficient human-to-human transmission mechanism, but as the virus continues to evolve, the risk cannot be ruled out.

We need active and passive annual surveillance networks under One Health that connect human and animal surveillance in a shared environment.

Importance

Wastewater-based epidemiology or pathogen surveillance has become an integral component of environmental surveillance providing near real-time information on health and community exposure to pathogens. Environmental surveillance is not a new concept and is widely used for surveillance of several pathogens, but it offers a great tool.

Birds infected with avian influenza virus shed large amounts of virus in their faeces, saliva, and nasal secretions for about a week.Wild water bird of meeting duck eyes and Cathodriformes It is the primary host of viruses. Virus transmission within these wild bird populations relies on fecal/oral transmission through contaminated water.

Avian influenza viruses have been isolated from unconcentrated water from lakes in the United States, Canada, and China. Repeated infection of animal hosts by viruses poses a persistent threat. Establishing large-scale influenza A virus surveillance networks across multiple sites is important to improve our understanding of virus diversity, seasonal and geographic distribution in the environment associated with poultry and wild birds. Monitoring should be targeted where spillovers are most likely.

Avian influenza viruses can persist in surface waters and carcasses for long periods of time, suggesting that lakes and wetlands may act as environmental reservoirs for months at varying temperatures. In a study, the H3N2 virus was isolated monthly from faeces and pond water over a period of one year, and the maintenance of this virus relies on environmental persistence and continued introduction of susceptible ducklings. was proposed.

Domestic ducks are recognized as important hosts for H5N1. Environmental surveillance is an important area that can enhance information on the prevalence diversity of avian influenza viruses in free-range livestock herds or under confined conditions where faeces and other wastewaters accumulate in the environment.

virus monitoring

Currently, virus surveillance is passive and relies on dead bird sampling. Environmental monitoring can be done without disturbing the birds and would be an excellent non-invasive tool that could be used to obtain the genetic material of both hosts and viruses.

Most importantly, environmental monitoring should be complemented by effective carcass collection and inspection, and improved poultry farm biosecurity to improve future preparedness and response.

( Farah Ishtiak is a scientist at the Tata Institute of Genetics and Society, Bangalore.)