The solution, SNIPERS!
http://www.ibtimes.co.uk/articles/437326/20130220/iran-rats-tehran-snipers-mutated.htm"They are now bigger and look different. These are changes that normally take millions of years of evolution. They have jumped from 60 grams to five kilos, and cats are now smaller than them."
To stop them storming of restaurants' backyards and scavenging public waste containers, the council has deployed ten snipers teams armed with infra-red sighted rifles.
Man this shit is fucked, lol, suddenly that time spend fighting giant rats in rpg's seems less silly, look at the size of that thing!