MUTANT "super rats" that are resistant to common poison are widespread in Gloucestershire, new research has found.
Around 75 per cent of rats in the county have a mutated gene which makes them immune to commonly sold poison compounds, such as Bromadiolone and Difenacoum, according to scientists at Huddersfield University.
Dr Dougie Clarke, head of biological sciences at the university, said the resistance to the poisons started as a natural mutation in around one per cent of rats around 50 years ago. It has gradually spread through breeding.
He said: "You can give these rats the poisons forever and they will never succumb, so they are a type of super rat.
"It's not the dosage that's the problem, it's these compounds specifically.
"If you use a different compound, these super rats could be wiped out within a week."
The scientists took a sample of 10 rats from Cheltenham and Gloucester to conduct their research, which is still ongoing.
Bromadiolone and Difenacoum are found in popular rat killer products made by pest control companies such as Rentokil and The Big Cheese, and are sold in DIY stores and online.
Although the research was not yet complete, the scientists said that all rats in Gloucestershire could be immune to these poisons within 10 years.
Their study will later survey 25 councils across England and test samples from around 600 rats in total. So far, around 300 samples have been tested.
Graham King, who is a pest control technician for Pestforce Gloucestershire, said he had seen success using Bromadiolone and Difenacoum.
He said: "I have had no problem at all in Cheltenham or Gloucester using these poisons. "The stuff I use is for professional use only, and I get it from registered companies. You can't just buy it in a DIY store."
Earlier this month workmen had to dig up pavements in the Battledown estate in Cheltenham after residents complained that their homes were infested with rodents.
Taylor Wimpey, which developed the estate, raised the paving to investigate how the rats were accessing the homes.
This was after a surveyor found that poorly laid drains had allowed the rats to crawl into one home.
Taylor Wimpey sent in the workmen following an investigation by the Echo and BBC consumer show Watchdog.
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