I'm sure that they can die die from parasites if they were bad enough. Eventually it would prevent the dragon from absorbing the nutritents of their food, however I doubt yours have such a high count.
If you weight your dragons, you can order some Reptaid. It's a herbal supplement that has shown wonderful results on coccidia, along with respiratory infections, mouth rot, appitite boosters, and is very mild.
Here's the website if you'd like to read up on it
http://reptaid.com/
There is also a thread on it on this website. It's stickied, so it shouldn't be too hard to find.
I wouldn't reccomend letting your dragons go untreated for any length of time, and it's possible that they do not have parasites and it could be the rocket, however a fecal test will be the only way to find out for sure.
As I've said, you can order a fecal kit online for cheap, under 10 dollars I think, and you can also order the meds online, if you didn't want to do a vet trip. Though if you treat them with medication, you will need to make sure you have the right dosage for their levels of parasites.