The sudden death of nearly 1,500 crows in Chennai, Tamil Nadu, confirmed as bird flu, has once again brought global attention to the growing threat posed by avian influenza viruses. At the centre of concern is Highly Pathogenic Avian Influenza (HPAI) H5N1, a strain known for causing mass mortality in birds and sporadic but often severe infections in humans.

H5N1 has circulated globally for years and is no longer considered a localised outbreak risk. India has reported repeated infections across multiple states, including Tamil Nadu, Kerala, Maharashtra, Andhra Pradesh, Telangana and Jharkhand, primarily affecting poultry but increasingly spilling over into wildlife. Similar outbreaks have been recorded worldwide, devastating bird populations across continents.

According to World Health Organisation data, between 2003 and 2025, nearly 1,000 human cases of avian influenza were reported across 25 countries, with a fatality rate of approximately 48 percent. Most human infections have been linked to close contact with infected animals, especially poultry, though recent cases among dairy farm workers have raised new concerns.

While sustained human-to-human transmission has not been confirmed, experts are alarmed by infections in people without clear exposure to birds or wildlife, suggesting the virus may be adapting in unpredictable ways. Medical specialists warn that bird flu can cause illness far more severe than seasonal influenza, with symptoms ranging from high fever and respiratory distress to rapidly progressing pneumonia.

Health authorities stress that continued surveillance is critical. Although the WHO notes no confirmed human-to-human transmission of H5N1 since 2007, past clusters suggest limited transmission could not always be ruled out. The Chennai outbreak serves as a reminder that while bird flu remains primarily an animal disease, its implications for human health are increasingly difficult to ignore.