We're often bitten by those really small ticks during the summer in rural central Virginia. The small ones make such light footsteps that you don't necessarily feel them walking on you.
At the site of infection/bite there will be a dark 'bullseye' pattern on/under the skin. If this is not detected (and treated), it will advance next into a condition described as 'flu symptoms.' In the advanced/later stages it gets really serious and is frequently not detectable, arthritis, fatigue, depression and mental confusion are just some of the symptoms. (It will vary somewhat from person to person) I thought I had it at one time and am still not sure I don't.