From what I've gathered the ticks are infected with a number of nasties which they might
vomit into you if they feel like. A bit like mosquitoes passing on the malarial
parasite I believe.
The ticks themselves 'quest' by lurking on long grass and other foliage and wait patiently
for some warm-blooded victim to wander past - they will then hitch a ride and crawl
around until they find a nice spot to dine.
It's not just Lyme disease (Borreliosis) but there are a number of other "things that can get
you" - although it is pretty unlikely. The chances of being bitten by a tick appear to be
reduced by wearing long sleeves / tucking trousers into socks, that sort of thing. The
chances of being infected with anything (and not all ticks are carrying anything) are also
reduced by checking regularly - some sites say once every day, some say more often -
for ticks and removing them.
People here have recommended the O'tom tick remover which you can get from
http://www.bada-uk.org/index.html
which is a great site that will tell you far more than you ever wanted to know about ticks.
Ticks are easy to miss when they first attach - they're not terribly large by the looks of
things - but they soon get a lot bigger once they start their meal. The goal appears to be
to get them off before they get much bigger (the longer they are on the greater the
potential risk of them transferring the nasties) and you might not manage this with just
a visual inspection.
I have also seen mention of using DEET stuff to prevent bites.
I'm afraid I don't know much about how they relate to human-animal interactions - it's all
a bit new to me and I'm regurgitating information rather than actually having my own
independent knowledge of it. There are a few threads here that are definitely worth
reading.
If you feel inclined, you could keep hold of any tick you find in a container labelled with the
date on which you find it - although I think I'd probaby want to burn it myself hehe. I think
the idea behind this is in case you feel unwell afterwards and the tick might 'help with
enquiries' - from what I read at the BADA site, getting a diagnosis isn't straightforward.