In particular, here on the east coast we have something called "Lyme Disease" which is tick borne. And not just any tick, only deer ticks carry it and they are hardly bigger than a freckle. I live in a heavily wooded lot and I have had the misfortune of having it twice. So when you cross to the east side of the Mississippi start being careful for them, use the DEET as John suggests if you want to be extra cautious, I think they even make DEET infused socks you could use around the campground. And if you feel a tick that's dug in (it will be quite sore to the touch and a little rough bump like a small mole got torn free) look to see if a bullseye rash develops over the next couple of days. Even if a rash doesn't show, IF a tick gets bored in (it takes 24 hrs for it to transmit) go see a doc and get tested at the end of your trip. I don't think Lyme exists in England so if you started to develop symptoms when you got home they wouldn't know to look for it.