In recent news, there has been growing concern over the H5N1 subtype of avian influenza, or bird flu, which has shown potential transmission between mammals. Researchers are probing a suspected spillover event after witnessing the death of over 700 seals along the coast of the Caspian Sea. This incident happened following the discovery of an H5N1 variant in wild birds inhabiting the same region.
Understanding Avian Influenza (H5N1)
Avian influenza is a disease caused by Type A avian influenza viruses. While these viruses typically infect birds, they can sporadically cross species barriers and infect mammals – an occurrence known as a spillover. Particularly, the H5N1 subtype of avian influenza has shown potential to infect other mammals such as minks, ferrets, seals, domestic cats, etc., through contact with infected birds, their faeces, or carcasses.
Symptoms of H5N1 in Humans
Upon infection, human symptoms can range from mild to severe influenza-like illnesses. These include fever, cough, sore throat, muscle aches, nausea, abdominal pain, diarrhoea, and vomiting. In some cases, people may also develop severe respiratory illnesses, such as difficulty breathing, pneumonia, acute respiratory distress, and viral pneumonia, or even experience altered mental status and seizures.
Avian Influenza Situation in India
In 2019, India was declared free from Avian Influenza (H5N1) by the World Organization for Animal Health (OIE). However, outbreaks of avian influenza H5N1 and H5N8 emerged in poultry across 15 Indian states in December 2020 and early 2021.
Treatment for H5N1 Infection
Certain antiviral drugs have shown potential in reducing the duration of viral replication and increasing survival chances. However, further clinical studies are required to confirm these findings.
Impact and Concerns of H5N1 Outbreaks
Outbreaks of H5N1 influenza not only cause considerable economic damage by affecting the poultry industry but also pose threats to food and vaccine security. These outbreaks also bring attention to issues related to animal welfare and environmental health.
Classification of Influenza Viruses
There are four types of influenza viruses known: Influenza A, B, C, and D. Influenza A and B are the ones mostly responsible for seasonal epidemic infections. Influenza C has been found primarily in humans, dogs, and pigs while Influenza D is mainly found in cattle, although it has not yet been known to cause illnesses in humans.
All About Avian Influenza Type A Viruses
Type A viruses are categorised based on two proteins present on their surface – Hemagglutinin (HA) and Neuraminidase (NA). There are roughly 18 HA subtypes and 11 NA subtypes, leading to numerous possible combinations—H5N1, H7N2, H9N6, H17N10, H18N11, etc. All known subtypes of influenza A viruses can infect birds. However, the H17N10 and H18N11 subtypes have only been detected in bats.
For those preparing for the UPSC Civil Services Examination, it’s useful to know that the H1N1 virus, which causes Swine Flu, was a focus area in the 2015 examination.