Ticks can lay dormant for months. In warmer weather they can stay on a blade of grass for an eternity waiting for a host to wander by. Usually a deep long freeze will kill them off, but from what you guys are saying, that didn't happen. The best prevention is just that PREVENTION. Use the sprays with premithin, make sure all cuffs are tight around your ankles and wrists, wear light colored clothing underneath to facilitate a check, check armpits, behind the knees, and your crotch. Ticks like warmth, and they will gravitate to those areas if not found.
If you have a tick that has clamped on, do not tug on it or pull it. Cover it with a layer of either vaseline or dishwashing detergent. LEt it sit for a bit. The tick cannot breathe and will release. Save the tick and get to doctor's ASAP. Same goes for a dog as well, although they now sell the tick removers, it's a bit of a chore if you have a dog that gets annoyed.
Doxycyline is a powerful drug, it is the go-to AB of choice when you need a full frontal attack on what germ is harming you. Drink lots of fluids and take some probiotics as this can wreak havoc on your stomach. Hope you get better soon.
I once appraoched my deer kill and it looked like it was covered with green/brown coffee beans. They were ticks that were engorged on the deer blood. Literally hundreds were on this animal. I left it for a while, giving them the time to jump off of their buffet before field dressing. As a side note, the skull plate still had some hair on it, so I placed it in a plastic bag. I forgot about it for a few weeks, and when I went to take the antlers out, there must have been some ticks on it and the ticks were still alive after weeks of being in a sealed plastic bag.
I don't know what positive purpose they serve, they carry disease is all that I am concerned with.