Bhubaneswar, Feb 23 (IANS): The Odisha government has alerted all its district authorities after a swab sample collected from a migratory bird tested positive for bird flu, an official said here Saturday.

The samples of some migratory birds in Chilika Lake were sent to the High Security Animal Disease Laboratory in Bhopal Jan 20 after they were found having flu-like symptoms, said Satyabrata Sahu, state secretary of the fishery and animal resources department.

The veterinary staffs of all the districts have been ordered to monitor health of all the birds after swab from one bird tested positive. The test report reached Friday, Sahu said.

The 1,000 sq km Chilika Lake, about 100 km from here, is spread over the districts of Puri, Khordha and Ganjam along the eastern coast and is home to some of the largest congregations of migratory birds in the country.

Every year, about a million birds from places as far as Siberia, Iran, Iraq and Afghanistan come to the lake in October and return in March.

This year over eight lakh migratory birds had visited the lake.

"There is no need to panic as 90 percent of the migratory birds have already returned back from the lake," Sahu told IANS.