It is likely that some of the Gators in My back yard will test positive for West Nile Virus.
I believe that tribalism is a natural defense against the spread of disease, lacking that instinct, or ignoring it, may be costly.
It seems likely but, unfortunatly, fleas and rats don't have tribes or the Black Plague wouldn't have made it to Europe. If your chickens start dropping dead, it is probably not a good idea to feed them to the gators.
Better stock up on gator repellent!
If you somehow get a few gator bites, probably West Nile Virus is the least of your concerns. ;)