The municipalities with the worst rat problems in the USA are also the municipalities with the greatest populations of community-vermin cats. Surprising? Not at all. Here's why:

The myth about cats being good rodent control has been disproved on every island where cats were imported to take care of the imported rodents. Hundreds of years later and there's nothing but a thriving population of cats and rodents.

The rodents reproduce in burrows and holes out of the reach of cats, where they are happy to reproduce forever to entertain cats the rest of their lives, and make your own lives miserable, on into infinity. On top of that, when cats infect rodents with cat's Toxoplasma gondii parasite, this hijacks the minds of rodents to make the rodents attracted to where cats urinate. http://scitizen.com/neuroscience/parasite-hijacks-the-mind-of-its-host_a-23-509.html

The plague is now being transmitted to humans in N. America directly from cats that have contracted it from rodents.