A local authority displays some captured mice at the cropland in Yueyang of central China's Hunan Province, July 10, 2007. An estimated 2 billion field mice are chomping their way hungrily through crops in 22 counties around the Dongting Lake in Hunan after their homes on islands in the lake were flooded. Local authorities in Yiyang, Yuanjiang, Junshan and Huarong are rushing to build walls and dig ditches to keep the mice away from flood-control dikes and cropland. (Xinhua Photo)

    CHANGSHA, July 11 (Xinhua) -- Authorities are on the alert for possible disease outbreaks after an estimated 2 billion rats chomped their way through crops in 22 counties around Dongting Lake in central China's Hunan Province.

    Li Junhua, spokesman for the Hunan Center for Disease Control and Prevention, said Wednesday work teams have been sent to three cities on Dongting Lake -- Yueyang, Yiyang and Changde -- to help prevent outbreaks of disease.

    Sixteen experts on the prevention of infectious diseases have gone to the area, including three from the Hunan Center for Disease Control and Prevention, nine from the Hunan Provincial Health Department, and the Beijing-based Chinese Center for Disease Control and Prevention.

    Li said there were no reports of disease caused by rats so far.

    The Hunan Provincial Health Department on Wednesday ordered local authorities to initiate a communication campaign, keep a close watch over the rodent situation and make daily disease reports.

    More than 2.25 million rats -- about 90 tons of rodent -- have been killed since June 21 in Yiyang, local authorities said.

    Cao Zhiping, head of the Yiyang office of plant protection and quarantine, said the dead rodents had been buried deep in the earth after being sterilized with quicklime and hence would not cause disease.

    In Lujiao town, Yueyang, dead rats were burnt and buried in high ground so that they could not be carried away by flood waters and contaminate the environment.

    The estimated 2 billion rats invaded 22 counties around Dongting Lake after their homes on islands in the lake were flooded.

    The rats burrowed through dikes and spread out into cropland, devouring crops along their route.

    Local authorities in Yiyang, Yuanjiang, Junshan and Huarong are rushing to build walls and dig ditches to keep the rats away from flood-control dikes and cropland.

    Poison has also been widely used to kill the rats but has already had side effects. In Binhu village of Lujiao town, about one thousand cats died after eating rats killed by poison.

    China's Ministry of Agriculture and the Hunan provincial government have altogether allocated 900,000 yuan to eradicate the rats, while in the Datonghu District of Yiyang City, 3 million yuan has been spent on killing rats, building walls and digging ditches.

    "The rat outbreak is more or less under control in the Dongting Lake area. The number of rats is dwindling," said Cheng Haibo, director of the Hunan Provincial Agriculture Department, at a press conference on Wednesday.