Mass death of ducks at Thalavady and nearby areas has created panic among farmers in the region.
At least 4,000 ducks died in recent days, sources said here.
Animal Husbandry Department officials on Wednesday ruled out the possibility of bird flu in the poultry deaths.
Samples collected
"We have collected samples and conducted an examination at a laboratory. It has revealed the cause of death as a bacterial infection. The ducks were infected with Riemerella anatipestifer .
There is no need to panic. We have taken precautionary measures to prevent the disease from spreading," said Mary James, Alappuzha District Animal Husbandry Officer.
Last month, a large number of ducks succumbed to bacterial infection at Pavukkara, near Mannar.