A rat infestation at home can put your family at risk of unwanted health conditions. Rats are associated with a number of life-threatening diseases such as lassa fever, hantavirus and leptospirosis.

Getting rid of these pests is not easy because rats are intelligent and they always seem to find ways to evade baits so imagine what it is like to deal with giant rats that are immune to supposedly feasible methods of killing them.

Unfortunately, such giant rats are no work of fiction. They exist and are now causing problems in Liverpool. Pest controllers said that they're seeing bigger rats for the past few months and describe them as super rats because they're as big as small cats.

There are also plausible explanations for the rodents' size. The mutant rats have apparently grown so big because it is easy for them to find food. The rat-catchers said that more foods are now left on the streets and rats consume these.

"Access to food is so easy for them," said Sean Whelan of Whelan Pest Prevention. "They're like humans, they eat and eat and get bigger and bigger."

One of the captured rodents is almost two-feet long and experts believe these giant rats feed on fast food and household wastes.

More alarmingly, the mutant rats are also becoming resistant to the baits that were commonly used to kill them. The Bromadiolone-based rodent killer as well as the blood-thinning drug warfarin-based poison that was widely used from 1960's to 1970's no longer work on these giant rats. Pest controllers say they're already planning to use stronger poisons albeit this would require a green light from the Health and Safety Executive.

"They're becoming very resistant to bait in Liverpool," Whelan said. "Soon we'll have to be putting third generation bait down which we will need to get legislation for."

The pest controllers can attest to the growing rat infestation as well. They said that they're supposed to receive fewer call-outs for rats because it's summertime and the weather is warm but they're not. The number of rat-based reports that Whelan's company received in the last year has also increased by 15 percent.