People for Ethical Treatment of Animals (PETA), Mumbai, today linked bird flu in Tripura to unhygienic condition of chicken and egg farms. This comes at a time when the State Government has blamed Bangladesh for the spread of the H5N1 virus through unchecked poultry movement from across the border. PETA officials here said besides Tripura, they had issued general warning to every State in India early this year about filthy condition in poultry farms after conducting a random survey and cautioned that it could lead to spread of the flu virus.