It was confirmed to the district administration by the state government through a letter on Thursday, Jalpaiguri District Magistrate, R Ranjit told The Indian Express.

"Samples sent from Saheber Tamar and Shyampukuria in the Sadar block have been confirmed as infected with bird flu. Random samples were taken after the unnatural deaths of around 200 birds and sent for testing. Following the confirmation, culling operations will begin tomorrow within 5 km radius of both the affected areas. According to our estimates, 50,000 birds are to be culled," said Jalpaiguri District Magistrate, R Ranjit.

After the outbreak of the virus in mid-January, the government had claimed to have completed culling and mopping-up operations in February. March, however, saw the re-emergence of the virus in the already-affected Murshidabad and Malda districts.

The state Animal Resources Development Ministry has been jolted into groping for answers for the re-emergence of the disease in March. On March 7, samples from two blocks in Murshidabad were tested positive, followed by an outbreak in Malda two weeks later. While the state government had culled over 3.5 million farm birds -- mostly chicken -- during the initial outbreak that affected 14 districts, nearly 70,000 birds have been culled since March 10 in Murshidabad and Malda.

Since then, Animal Resources Development Minister of the state Anisur Rahaman has been working overtime to reassure the public that it is safe to consume chicken with the prescribed safeguards. He has organised several "chicken parties" in which he has consumed chicken dishes. With the panchayat elections tentatively scheduled for May, the ruling CPM government is stretching itself to reassure poultry farmers across the state as thousands of them have lost their poultry birds to the culling exercise. Rahaman, however, could well read a report released by the Food and Agriculture Organisation (FAO) today.

Initiated and coordinated by senior veterinary officer FAO, Jan Slingenbergh, the research uses a modelling technique to establish how different factors -- including ducks, geese, chickens, human population size, rice cultivation and local geography -- contributed to the spread of the virus. It notes "ducks, people and extent of rice cultivation rather than chicken are the major factors for the outbreak of H5N1 in Thailand and Vietnam. These are probably effecting the persistence of the virus in other countries of the region such as Cambodia and Laos."

The FAO report, "Mapping H5N1 Highly Pathogenic Avian Influenza Risk in Southeast Asia: Ducks, Rice and People", is published in the latest issue of the Proceedings of the National Academy of Sciences of the United States (PNAS).

A group of experts from FAO and associated research centres studied the outbreak of H5N1 in Thailand and Vietnam between early 2004 and late 2005.