DHAKA (Reuters) - Bird flu has spread to three moredistricts of Bangladesh, the livestock department said onSunday, taking the number of affected districts to more thanhalf of the country's 64 districts.

The latest outbreaks were reported in southwesternGopalganj, northeastern Sylhet and northern Mymensinghdistrict, officials said.

The port city of Chittagong was put on high alert aftersome dead crows tested positive for the H5N1 virus, localofficials said.

Officials said the government was taking measures tocontain the spread of the disease, but ignorance among millionsof farmers across the impoverished country remained a stumblingblock.

Despite a government drive to burn or buy the dead birds,many farmers and backyard poultry breeders continue to ignorewarnings, officials said.

"More than 200,000 volunteers are visiting rural householdsand educating people to report dead or sick birds, safedisposal of poultry waste and other safe health practices,"said Mushtaque Ahmed, senior scientific officer at theInstitute of Epidemiology, Disease Control and Research.

Touching or eating sick poultry is the common way to becomeinfected by the bird flu virus that has killed more than 220people globally since late 2003.

So far no human infection has been reported in Bangladesh,though some 4 million people are involved in poultry farmingacross the country.

The neighboring Indian state of West Bengal has put 26people in isolation with bird flu symptoms after the mostserious outbreak of the disease in poultry.

(Reporting by Ruma Paul; Writing by Anis Ahmed; Editing bySanjeev Miglani)