Scots ‘super rats’ are immune to poison

Experts studied their tails and it showed the rats, trapped in Glencaple, Sanquhar and Kelton in Dumfriesshire, have developed “100 per cent immunity” to known poisons.

Scientists ran tests to determine how effective rodenticides and other household chemicals were in tackling the pests.

But every one tested at Huddersfield University was “resistant to poison”.

Local exterminator John Lynch, of All Out Pest Control in Auldgirth, said: “It comes down to what rodenticide people use – what strength it is and what’s in it. If someone uses the same one to kill different generations of rat then it can lead to a resistance.”

Experts say the danger of growth in the rat population is a rise in the risk of diseases they carry.

In particular they spread Weil’s disease, also known as leptospirosis, a bacterial infection that can prove fatal.

In 90 per cent of cases it causes mild flu-like symptoms, including headache, chills and muscle pain.

But where the infection takes hold of the body and is more severe, it can cause organ failure and internal bleeding. The disease is spread in water contaminated with rats’ urine.

Professor Dr Dougie Clarke of Huddersfield University said: “People should be concerned. Rodenticides will kill off the normal rats but the resistant ones will remain.

“It’s a sort of time bomb of resistance building up over generations of rats.”

A spokesman for Dumfries and Galloway Council said: “The council’s pest control service is seeing little evidence of resistance in its day-to-day operations, but is closely monitoring the situation for any change.”