Mice have been swarming the western New South Wales country town of Gilgandra for several weeks, in what locals are saying is the worst mice plague in decades.Eyewitness video obtained by Reuters showed thousands of the rodents swarming around a local farm in Gilgandra.Farming communities have been hit the hardest by the uptick in mice, with supermarkets storing food in sealed containers and three patients at the local hospital being bitten, Australian media reported.Intensive baiting programs are being tried with little signs of reducing keeping the vermin numbers down, so locals are hoping for heavy rain to drown the mice in their burrows.According to local media, just a pair of mice can produce up to 500 offspring in a season on average.