What diseases do pet squirrels carry?

Answer 1

While it's a well-known fact that squirrels carry rabies and rodent plague, by far the most DANGEROUS thing they do is to carry Lyme positive ticks into your yard, to be carried into your house by your pets. You too, can pick up these ticks when you handle plants where the ticks have crawled off of the squirrels.

Squirrels can be cute to admire from a distance, but it is now unwise to do anything to encourage them to visit your yard, unfortunately. Lyme is not in our radar because we didn't always have spirochetes in the ticks. That's a different story. It's said to have begun in a Plum Island lab off the coast of Old Lyme, Connecticut.

Squirrels are subject to rabies but they do not commonly carry rabies, and if you live in the city its highly unlikely that the squirrels have rabies because they aren't exposed to animals that do carry such as raccoons.