I wouldn't worry about ticks or chiggers but you will have to be aware of beg bugs and fleas. Yes, fleas! There are copious cats and dogs along the way that you may decide to visit and pat (more cats than dogs--lots of dogs are locked up as guard dogs and you wouldn't get close to them). And, alas (for me anyway) you may find yourself with a hitchhiker from one of the albergues. Yeah, from the albergues. :shock:
But ticks or chiggers? I think you don't need to be worried about them.
From experience I think you need to be more careful of poison plants growing along the roads. My wife got a bad rash from a plant that the locals call "Hortiga", It got through her pant legs. The section below was protected by her socks and the section above by a knee brace. In-between she got a really bad rash.
Since it was a pretty wet winter/spring, there are a lot of weeds growing along the road