Meanwhile, chickens are dying at different poultry farms in Gazipur of unknown diseases.

Of the 4,000 newly found infected fowls in Sharishabari, 1,900 chickens were culled yesterday and the rest are to be culled today.

The government has so far surveyed 1,436 farms in the country, of which 11 farms in five districts--Dhaka, Narayanganj, Gazipur, Tangail and Jamalpur--had bird flu infected fowls. More than 50,000 birds have already been culled in those farms, sources said.

A three-member investigation team yesterday visited the farm of Bangladesh Biman at Savar where the first official case of avian influenza was detected.

Adviser to the Ministry of Livestock CS Karim during a briefing at his office yesterday told journalists that the bird flu problem is not very acute in the country.

”Bird flu spread in other countries like forest fire. But here we are finding it in some pockets," said the adviser. Replying to a query, the adviser said if necessary the government might ask for technological and financial help from the international community.

Our Tangail correspondent reports: Bird flu was detected at a farm owned by Abdul Jalil at Rautbari near the Jamuna river. Around 2,000 chickens and 4,000 eggs were destroyed in presence of upazila livestock department officials last night.

Upazila Livestock Officer Dr Akhil Chandra told journalists that they received a fax from Dhaka notifying them that the chickens of that farm had bird flu. Earlier, the department had sent samples to a Dhaka lab to find out why 20 layer chickens died in the farm.

A correspondent in Jamalpur reports: 1,900 chickens were culled yesterday evening at Bhai Bhai Poultry Farm in Dikrirbandor of Sharishabari upazila. Director General of Livestock Department Sunil Kumar visited Sharishabari yesterday and supervised the chicken culling, the report added.

The livestock department officials would be culling another 1,850 chickens today at Hazi Poultry Farm at Dalikandi union in Sharishabari.

Our Narayanganj correspondent reports: Narayanganj livestock department officials culled 2,300 chickens at Asad Poultry Farm in the district Monday night. A total of 2,400 chickens have so far been culled at two farms in Narayanganj.

Dead chickens of another farm at Kalyandi in the district have been sent to Bangladesh Livestock Research Institute (BLRI) to find out if they died of bird flu.

A three-member Epidemiology Investigation Committee comprising Dr Shahjahan, Dr Tulsidas Saha and veterinary surgeon Dr Mosaddeque Hossain visited Biman Poultry Complex at Ganokbari in Savar where the first bird flu case was officially detected, our Gazipur correspondent reports.

They tried to determine the reason and source of avian influenza in the country.

KM Hasibul Khaled, manager of the poultry farm, told the investigation team that they supplied 1,03,426 chicks to 58 farms at different places in the country from February 4 to March 3. The birds in those farms are under the risk of avian influenza infection.

Meanwhile, livestock department officials in Gazipur found another farm at Muradpur of Kaliakoir in Gazipur where 72 birds died in three days.

Dr Kafiluddin, district livestock officer, told The Daily Star last evening that he did not think it was a case of avian influenza infection even though he had sent samples to a lab to find out the reason for the chickens' death.

Meanwhile, chickens are dying due to unknown reasons at several poultry farms in Gazipur.

The Gazipur livestock officials formed a team to estimate the amount of loss at different farms in the district.