DO NOT leave rats alive to breed!!! For every one you see in daylight there are at least another six you can't see, and they breed at an incredible rate; add to this eighteen months of mild weather which has meant abundant food and almost continuous breeding...............They're a menace in health terms and they eat enormous amounts of grain and stuff, and contaminate it in the process.
The real cause for concern is, however, leptospirosis, a viral liver disease which a very dangerous and unpleasant thing to get at the best end of it and life threatening at the worst; even if you get over it you'll never be the same again and it's on the increase in a big way.
Rats dribble urine continuously as they go about and it gets on everything they go near, and that's where the lepto comes from. All the time it's wet, it's active, and all the time it's over four degrees C it's active and transfers readily through the tiniest nick in the skin, or by touching your mouth with hands or clothing that've been in contact. It's all over your dog's and your cat's feet and bodies but they're innoculated, but you're not and neither are your kids when they bring it in from the garden or the fields................
Get rid of the little sods on sight and stop stupidly anthropomorphising and causing problems for everyone else....
Red in tooth and claw!!!