H5N1 Avian Influenza Confirmed at Vandalur Zoo

H5N1 avian influenza was confirmed in water birds at Arignar Anna Zoological Park, also known as Vandalur Zoo, in Chennai, Tamil Nadu. The National Institute of High Security Animal Diseases (NIHSAD), Bhopal, confirmed the infection on 2 October 2026. Seven water birds died between 3 and 9 October.

Avian Influenza and H5N1

Avian influenza is an infectious disease caused by influenza A viruses that primarily affect birds. The H and N in the designation H5N1 refer to the virus surface proteins haemagglutinin and neuraminidase; the numerals identify their subtypes. H5N1 is one subtype of avian influenza A virus. Wild water birds can carry avian influenza viruses, and infection may spread among birds through contaminated secretions or environments.

Bird Mortality at Vandalur Zoo

The seven deceased birds comprised four painted storks, one grey pelican, one grey heron and one oriental darter. The birds were housed in the zoo’s Vedanthangal enclosure. Zoo officials cordoned off the affected area after the first bird died on 3 October. No further bird deaths or signs of illness had been reported since 9 October, and the zoo director described the outbreak as likely over.

Biosecurity and Preventive Measures

The zoo closed to visitors on 22 and 23 October 2026 to allow intensive sanitisation, reinforce biosecurity and monitor the affected area. Measures included disinfection, sanitisation and restricted access to the affected zone. Water birds were given oral antibiotics, herbal antiviral medicines, immunostimulants and liver supplements. Biosecurity measures in animal facilities include controlling movement between enclosures and preventing the transfer of infection by people, equipment or contaminated materials.

Important Facts for Exams

• H5N1 is an influenza A virus subtype named for its haemagglutinin 5 and neuraminidase 1 proteins.
• NIHSAD is located in Bhopal and confirmed the infection at Vandalur Zoo.
• Arignar Anna Zoological Park is located at Vandalur in Chennai, Tamil Nadu.
• Painted storks, grey pelicans, grey herons and oriental darters were among the birds that died.

Vandalur Zoo is also known as Arignar Anna Zoological Park. H5N1 confirmation led to a two-day visitor closure on 22 and 23 October 2026.