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Hordes of rats and mice are moving into new towns and villages built for people displaced by the Three Gorges dam, raising fears of disease epidemics in the resettlement zones, the Hubei Daily (Hubei Ribao) reports.

As officials in Zigui county near the dam site prepare to use almost 22 tonnes of rat poison in a cleanup campaign, they have been alarmed to see that hungry rodents are migrating in droves from the abandoned settlements to the new ones in search of food. People who have been resettled in the reservoir area are also distressed to discover that large rodents have followed them to their new homes, the newspaper said in its Aug. 9 report.

Officials are particularly concerned about the danger of an epidemic of leptospirosis, an acute infectious disease that can cause kidney failure and meningitis. Humans contract the disease through contact with water, wet soil or vegetation that is contaminated with the urine of infected animals, with rats being considered the most significant threat.

Mei Changqing, director of Zigui’s epidemic-prevention bureau, said a serious leptospirosis outbreak that followed the construction of a dam on a Yangtze tributary two decades ago holds an important lesson for the builders of the Three Gorges project.

He said that in the case of the earlier dam, which he did not name, no effort was made to exterminate rats and mice before the reservoir was filled, and the sudden concentration of rodents in settlements on higher ground was responsible for a deadly epidemic.

If the Three Gorges dam area is not completely cleared of rodents before its reservoir is filled to the 135-metre level next June, “there will be no end of trouble ahead,” the disease-control official warned.

Prof. Lu Shengye, a public-health expert at Wuhan’s Huazhong University of Science and Technology, has also raised concerns about reservoir-related epidemics in an article in China Three Gorges Construction, an acadmic journal published by the Three Gorges Project Corp.

Writing in the May 2002 issue, Prof. Lu says a leptospirosis outbreak occurred after the Geheyan dam was built a decade ago on the Qing River, a Yangtze tributary. Rats contaminated rice fields near new settlements built as part of the Geheyan project, causing an epidemic that killed an unspecified number of people, he writes.

Experts from around the country met in Chongqing recently and decided to use a new rat poison in the Three Gorges reservoir cleanup campaign that is said to kill rodents painlessly within a week, but is deemed harmless to humans, the Hubei Daily said. To ensure the poison does not contaminate the water of the future reservoir, workers will be dispatched throughout the area to collect the rodent corpses and burn them.

Teams of workers are now receiving technical training in Zigui in preparation for the rodent-extermination campaign that is to be launched soon, the newspaper reported. An estimated 100 tonnes of poison will be needed to get the job done throughout the Three Gorges area, it said.