Why in news?
Since 2020, a highly pathogenic type of bird flu, H5N1, has been spreading across the globe, posing an existential threat to birds and wildlife. The virus has infected birds in more than 80 countries (as of December 2023).
In January 2024, the Executive Director of Health at the Wildlife Conservation Society said that H5N1 has infected over 150 wild and domestic avian species around the globe as well as dozens of mammalian species.
What’s in today’s article?
Bird Flu
- About
- 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 without much harming them.
- Cause of concern
- 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.
H5N1 Bird flu
- About
- H5N1 is a type of influenza virus that causes a highly infectious, severe respiratory disease in birds called avian influenza (or "bird flu").
- Basically, it is a subtype of the influenza A virus.
- Influenza A viruses are classified by subtypes based on the properties of their surface proteins.
- There are 18 different hemagglutinin subtypes and 11 different neuraminidase subtypes (H1 through H18 and N1 through N11, respectively).
- For example, A(H1N1) and A(H3N2).
- Human cases of H5N1 avian influenza occur occasionally, but it is difficult to transmit the infection from person to person.
- When people become infected, the mortality rate is about 60%.
- Origin and circulation
- The currently circulating type of H5N1 has descended from a virus that caused an outbreak on a goose farm in Guangdong, China, in 1996.
- The new version of H5N1 first emerged in Europe in 2020 and then rapidly reached 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.
- Reasons behind the large-scale spread of H5N1
- The exact factors behind the large outbreaks of the bird flu are still largely unknown. Some scientists suggest that one reason could be climate change.
- According to studies, soaring global temperatures impact the behaviour of birds in such a way that it exacerbates the spread of the flu.
- These birds are forced to move into new territories and mix with species that they usually don’t interact with, which possibly boosts the chances for the virus to spread even further.
- Higher sea surface temperatures might also be at play.
- E.g., warmer sea temperatures near northern Chile have led to a fall in the forage fish population and that has made sea lions weaker and more susceptible to disease.
- Spread of H5N1 to people
- Almost all cases of H5N1 infection in people have been associated with close contact with infected live or dead birds, or H5N1-contaminated environments.
- The virus does not infect humans easily, and spread from person to person appears to be unusual.
- Cause of concern
- H5N1 infection in humans can cause severe disease and has a high mortality rate.
- If the H5N1 virus were to change and become easily transmissible from person to person while retaining its capacity to cause severe disease, the consequences for public health could be very serious.
