A 70-member disaster management team is at Sambhar Lake.

A preliminary forensic report has indicated that the mysterious death of more than 4,800 migratory birds at the country’s largest inland water saltwater lake near Jaipur was caused by botulism, a serious and fatal illness that affects the nerves, officials said on Friday.

A 70-member disaster management team is at Sambhar Lake, a key wintering area for tens of thousands of migratory birds, to dispose the carcasses so that botulism does not spread to other birds. Also, a dozen teams from the Animal Husbandry Department are closely monitoring the situation.

Initially, it was suspected that the birds died due to avian flu but the report from a laboratory in Bhopal has ruled this out.

“Veterinary experts from Rajasthan University of Veterinary & Animal Sciences, Bikaner, have indicated that the deaths occurred due to botulism,” principal secretary (forest) Sreya Guha told PTI.

Jaipur District Collector Jagroop Singh Yadav said another report on the heavy metal toxicity in the lake is awaited from a laboratory in Coimbatore.

Mr. Yadav said Bikaner university experts have said the birds died to botulism.

“The birds died due to infection spread after feeding on maggots-infested carcasses. This causes paralysis in birds. The symptoms indicate that the cause of death was botulism,” he said.

On Wednesday, Rajasthan Chief Minister Ashok Gehlot said the death of birds near the lake was worrying and protecting the flora and fauna remains one of the priorities of his government.

On Sunday, thousands of birds, including Northern Shoveler, Ruddy Shelduck, Plovers, Avocets, were found were found dead in the 5-7 km area around Sambhar Lake.

This was the second such incident in the state within a week.

On November 7, 37 demoiselle cranes were found dead in Jodhpur’s Khinchan area. An investigation is on in that case as well.