KOLKATA, India (AFP) - Five people have been quarantined in eastern India with "clinical symptoms" of deadly avian flu following the country´s worst ever outbreak of the virus, reports said Tuesday.

All are residents of West Bengal state and are suffering from fever, cough, sore throat and muscle ache after handling affected poultry, the Times of India reported.

If the tests are positive, this will be the first case of human infection due to the deadly H5N1 strain in India, home to 1.1 billion people and hit by bird flu among poultry three times since 2006.

The five have been given antivirals as authorities await results of blood tests, the report said.

People typically catch the disease by coming into direct contact with infected poultry, but experts fear a flu pandemic if the H5N1 mutates into a form easily transmissible between humans.

Eight districts in West Bengal have been hit by the virus, with authorities reporting over 100,000 bird deaths and teams trying to cull 700,000 chickens and ducks.

But villagers have also been seen eating chickens killed by bird flu, or otherwise selling the meat at cheap prices.

Migratory birds have been largely blamed for the global spread of the disease, which has killed more than 200 people worldwide since 2003.