April 20, 2024

Lukmaan IAS

A Blog for IAS Examination




THE CONTEXT: Since its emergence in 2020, the highly pathogenic H5N1 bird flu virus has posed a significant threat to both avian and mammalian species worldwide.


  • The virus has led to mass mortality events among various bird populations and has also affected mammals, particularly marine species, raising concerns about its potential impact on biodiversity and ecosystem health.

Spread and Impact of H5N1 Virus

  • The H5N1 bird flu virus has spread rapidly across the globe, infecting birds in over 80 countries by December 2023.
  • Originating from China in 1996, the virus has evolved into a highly pathogenic form, causing significant mortality among domestic poultry and wild bird populations.
  • In recent years, the virus has also crossed species barriers, affecting mammals such as seals, sea lions, and even mainland Antarctica, signaling an unprecedented threat to wildlife.

Impact on Birds

  • Wild bird populations have borne the brunt of the H5N1 outbreak, with reports of mass mortality events among various species.
  • Particularly affected are waterfowl like ducks and geese, as well as seabirds such as gulls and terns.
  • Notably, endangered species like the California condor have also suffered losses, raising concerns about the conservation status of already vulnerable populations.

Impact on Mammals

  • The spread of H5N1 to mammals poses significant risks to both marine and terrestrial species.
  • Marine mammals, including sea lions, dolphins, and seals, have experienced devastating mortality rates, with tens of thousands of deaths reported in regions like Chile, Peru, and the United States.
  • The infection has also affected terrestrial mammals, including foxes, pumas, skunks, and bears, highlighting the broad reach of the virus across different ecosystems.

Unique Vulnerability of Marine Mammals

  • Among mammals, marine species are particularly vulnerable to H5N1 infection due to their close proximity in densely populated coastal areas and their dependence on healthy marine ecosystems for survival.
  • The mass mortality events observed among sea lions, dolphins, and seals underscore the severity of the threat posed by the virus to marine biodiversity and ecosystem functioning.

Factors Driving Spread

  • While the exact factors driving the large-scale spread of H5N1 remain under investigation, scientists have suggested that climate change may play a role.
  • Rising global temperatures alter bird behavior and distribution patterns, facilitating the spread of the virus across different regions.
  • Additionally, warmer sea temperatures can weaken marine mammals, making them more susceptible to diseases like H5N1.

Human Health Risks

  • While humans rarely contract bird flu, there is a risk of transmission, particularly among individuals working in close proximity to infected birds in poultry farms.
  • Although human cases are relatively rare, the potential for zoonotic transmission underscores the importance of vigilant surveillance and biosecurity measures to prevent outbreaks among both animals and humans.

Bird flu and H5N1:

  • Bird flu, also known as avian flu, refers to an infectious viral illness that mainly infects and spreads among poultry and some wild birds.
  • There are different strains of bird flu virus, which have been circulating for a very long time among at least 100 bird species, including wild waterfowl, such as ducks and geese, without much harming them.
  • From time to time, a form of the flu virus jumps from wild birds to poultry farms, and replicates in cramped warehouses of farmed birds.
  • It then quickly evolves into a highly pathogenic flu virus that causes a larger wave of illness and death than usual among birds.
  • The currently circulating type of H5N1 is one such highly pathogenic flu virus.
  • It has “descended from a virus that caused an outbreak on a goose farm in Guangdong, China, in 1996.
  • That virus — one of a type of virus known as H5N1 — was highly pathogenic and killed more than 40 per cent of the farm birds it infected.
  • The new version of H5N1 first emerged in Europe in 2020 and then rapidly reached Europe, Africa, and Asia.
  • By late 2021, it had spread to North America and in the fall of 2022, it appeared in South America.
  • In February 2024, the virus stormed through mainland Antarctica.

SOURCE: https://indianexpress.com/article/explained/explained-global/h5n1-bird-flu-mammals-9236846/

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