CHANGSHA -- Central China's Hunan Province said it has taken effective measures to prevent epidemics after about 2 billion rats chomped their way through cropland around the Dongting Lake, the country's second largest freshwater lake.

"It's not possible for rodent-borne diseases to break out in the lake area," said Chen Xiaochun, vice director of the provincial health department.

Local health authorities have been watching closely over the rodent situation after the rats fled their flooded island homes and invaded 22 counties around the Dongting Lake last week, he told a press conference on Wednesday.

Results of their observation are reported daily to the provincial health department and the public, he said.

Meanwhile, local health and disease prevention and control authorities have intensified management of raticide and pesticide, for fear they might contaminate food and water, Chen added.

No human infection of any rat-borne disease has been reported in the central Chinese province since 1944.

The provincial government also ruled out widespread suspicions that rats flooded the area because one of their natural enemies -- snakes -- had been served at dinner tables.

"The Dongting Lake area is not an ideal habitat for snakes," said Deng Sanlong, a top forestry official in the province, "and the only two species that inhabitate the region feed largely on fish and frogs."

He said the top enemy of the rats are hawks that spend winter in the wetland around the lake but fly away in spring.

China's Ministry of Agriculture and the Hunan provincial government have allocated 900,000 yuan in total to eradicate the rats.