Mutant “super rats” that have become immune to common poisons are spreading across Britain, scientists have warned.

Researchers from the University of Huddersfield tested rats in 17 counties and found rodents resistant to over-the-counter poisons such as Bromadiolone and Difenacoum in every single one. In more than 50 towns across the UK - from Reading to Sheffield to Dumfries and Galloway – they found rats who were 100 per cent resistant to common poisons.



Dr Dougie Clarke, who carried out the research, told ITV’s Tonight “people should be concerned”. “The fact we've tested 17 counties and every single one of them has got resistant rats was an amazing find to us. We didn't expect to have every single country having resistant rats.”



Rats carry diseases such as the bubonic plague and can damage homes and public property – and they have developed the immunity to pest control poisons over generations. As ecology Professor Steven Belmain explains: “We’re using the same group of chemicals over and over again, resistance will build up, so the UK, but also many other parts of the world, are suffering from this phenomenon”.



Although stronger, professional quality poisons are available to kill the rats they could also be damaging to other forms of wildlife or even domestic pets and they cannot be used outdoors without a license.



Dr Clarke warned that as well as implications for public health, super-rats will also increase the cost of pest control will escalate, saying: “Unless there's new legislation for the more toxic poisons and maybe for the more lax use of them, then it will have to be the more physical forms of killing the rats. The costs are going to escalate because of the monitoring and the picking off of the rats, and the dead bodies.”