Date: 20/02/2023

Relevance: GS-3: Science and Technology- developments and their applications and effects in everyday life.

Key Phrases: Avian Influenza (H5N1), Bird Flu, Active and Passive Year-round Surveillance Network, Wastewater-based Epidemiology, Pathogen Surveillance, Genome Sequencing

Why in News?

• The world’s largest northern gannet colony at the Bass Rock, an island off the coast of North Berwick, Scotland has been recently decimated by avian influenza (H5N1) or bird flu which caused unprecedented loss of tens of thousands of birds in the U.K.

Avian Influenza:

• Avian influenza, or bird flu, is a highly contagious viral infection that primarily affects birds.
• Infrequently, the virus can infect mammals from birds, a phenomenon called spillover, and rarely can spread between mammals.
• There are several different subtypes of avian influenza viruses, ranging from low pathogenic to highly pathogenic types that can cause severe illness and death in birds.
• H5N1 is a highly pathogenic subtype of avian influenza that causes severe disease and death in birds.
• This subtype has caused several human infections through close contact with infected birds, or contaminated environments and is often fatal.
• Recent reports of H5N1 transmission between mammals, therefore, raise concerns about its potential to cause a human pandemic

Intra-Mammal Transmission Of H5n1:

• Recently, the intra-mammal transmission of H5N1 in captivity in mink farms was recorded, posing a bigger concern concerning zoonotic potential.
• More recently in February 2023, Peru reported cases of H5N1 avian influenza in sea lions and a dolphin, and a lion dying from H5N1 in a zoo.
• This raises concerns about the potential for H5N1 to cause a pandemic in humans if it were to spill over and become transmissible among humans.
• It is also possible that over time, the virus could evolve through mutations or recombinations with other influenza viruses to adapt to new hosts, leading to further outbreaks.

Past Outbreaks:

• The H5N1 avian influenza virus was first detected in 1996 on a goose farm in China.
• Subsequently, a major outbreak was reported in 1997 among poultry in Hong Kong, also leading to human infections of H5N1, which left 6 people dead and 18 infected.
• In 2004, H5N1 was reported in several countries in Asia, and further, a global outbreak continues to date.
• In 2013 and 2014, many countries in Europe and Asia reported H5N1 in poultry.
• Over the years the virus has caused outbreaks across the world, predominantly spread by migratory birds.
• To date, over 800 cases of human H5N1 infections have also been reported, with a high fatality of 53%.

Avian Flu Outbreak In India:

• In India, the latest major avian flu outbreak in 2020-2021 swept through many states causing mass mortality of wild birds which brought concerns on the lack of active surveillance to the forefront, and how wetland and waterfowl habitats at the interface of poultry need to be monitored.

Challenges For India:

• India is a major wintering ground for many waterfowl that rely on the central Asian Flyway.
• While the avian flu outbreaks coincide with the peak migratory season leading to post-outbreak surveillance and culling, there are also reports of outbreaks in the off-season suggesting endemic transmission within the poultry sector.
• India is the fastest-growing egg producer in the world, but unlike in Europe, poultry birds here are not vaccinated against the flu.
• Furthermore, farms with a diversity of animals or in the vicinity of nearby wetlands increase the potential for the viruses to undergo reassortment that can potentially generate more virulent strains H5N1 or H7N9 — which could then infect humans.
• Despite this potential, there is no active surveillance in the poultry sector.
• There may be no efficient human-to-human transmission mechanism yet, however, the risk cannot be ruled out as the virus continues to evolve.
• We need an active and passive year-round surveillance network under One Health which connects monitoring of human and animals in a shared environment.

Wastewater-Based Epidemiology Or Pathogen Surveillance:

• 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.
• While environmental surveillance is not a new concept and has been used widely for monitoring several pathogens, it offers an excellent tool.
• Recurrent infections of animal hosts with the virus have posed a persistent threat.
• A virus surveillance network in place across multiple sites is crucial for improving our understanding of the diversity, and seasonal and geographical distributions of the virus in environments associated with poultry and wild birds.
• The surveillance needs to target the locations where spillover is most likely.
• Domestic ducks are recognized as an important reservoir for H5N1.
• Environmental surveillance is an important area that can enhance the information on the prevalence diversity of avian influenza viruses in free-ranging domestic flocks or under confinement conditions where feces or other effluent are deposited into the environment.

Way Ahead:

• Preventing H5N1 spillovers and outbreaks requires a combination of measures including
  • Vaccination of poultry
  • Safe disposal of dead birds
  • Quarantine and culling of affected animals
  • Wearing personal protective equipment when handling birds
  • Improved surveillance and monitoring of H5N1 in birds and other animals
• Human vaccines against H5N1 avian influenza have been designed to protect against the most severe forms of the disease.
• However, the highly mutable nature of the H5N1 virus could potentially decrease vaccine efficacy over time.
• Therefore, molecular surveillance of avian influenza and its subtypes is essential in understanding and responding to outbreaks.
• Genome sequencing can be employed to monitor mutations in the virus, and the emergence of new subtypes, and keep a close watch on mutations and virulence factors that may increase the ability to infect humans.
• This can inform public health decisions and guide the deployment of more effective control measures.

Conclusion:

• Although the risk of H5N1 infecting and spreading among humans has been evaluated as low, disease and genomic surveillance as an integrated approach to controlling avian influenza are needed to keep a close watch on the outbreak.
• As we learned from the COVID-19 outbreak, monitoring the evolution of the shapeshifting virus can add to the preparedness against another potential pandemic.
• Currently, virus surveillance is reactive and relies on sampling dead birds.
• Environmental surveillance would be a great non-invasive tool that can be done without disturbing the birds and can be used to obtain both host and viral genetic material.
• Most importantly, environmental surveillance should be complemented with effective carcass collection and testing, and better biosecurity on poultry farms to improve preparedness and response in the future.

Source: The Hindu

Mains Question:

Q. Mention challenges in dealing with the spread of the H5N1 virus and suggest measures to improve preparedness and response in the future. (250 words).