Guwahati: The People for Ethical Treatment to Animals (PETA) says that bird flu in Assam was due to farm filth. In a strongly-worded report they said, they had arrived at the conclusion after a secret survey was made on 40 farms in Assam, besides information from the Government departments. ''Leading health experts, including those at the UN, blame unhygienic conditions for the spread of the deadly H5N1 strain of bird flu. The report documents the scalding, starvation and mutilation of birds as well as the potential for the spread of disease from chickens to humans,'' said Nikunj Sarma, Programme coordinator of PETA who conducted the survey.