New medical research has also discovered the rats carry more disease- causing parasites than previously realised, and many of these can be transmitted to people by household pets.
Nearly a million homes in England are suffering from rat infestation, and there has been a 40 per cent rise in the number of homes infested in the last two decades. Much of it is said to stem from decaying sewers and drains.
A number of local authorities are now considering mounting a test case against privatised water companies under environmental and pest-control laws. It is claimed that while some of the companies have been making " fat-cat" payments to executives and directors, they have often drastically reduced funding for rat control.
Yorkshire Water, which has around 15,000 miles of sewers, wants to end its contract with the pest-control department of the local councils. Instead it plans to offer the contract to private companies .
Pest-control officers believe this is a recipe for major problems in the future. David Bird, environmental services manager of Sheffield council, said: "We are exploring the possibility of legal action over this. We feel such action can be brought under environmental and pest-control laws".
Yorkshire Water has denied that the move is is a cost-cutting exercise, and said the company would strive to maintain and improve the quality of service. In l995, the company reduced its sewer-baiting budget by one- third, although a small percentage of the money was later restored.
According to last night's Granada Television World in Action programme, the health risk is greater than previously recognised. Potentially fatal illnesses include Weil's disease, Q disease, toxic plasma, and hantavarius, which can cause liver and kidney failure.