There are only few laboratories in the USA, that we know of, which are competent to diagnose the presence of some parasites in the feces and in the intestines. BUT, not the presence of all species of parasites. Recognizing microscopic parasitic eggs in the feces is much harder job then finding bacteria, yeast or virus. "Good" labs are:
Meridian Valley Labs.
24030 132nd Ave. SE
Kent, Washington 98042
Great Smokies Labs.
18 A Regent Park Blvd.
Asheville, North Carolina 28806
You might also find a competent physician in your area by contacting these labs for that information.
It is generally cheaper and easier to do a herbal or Coenzyme Q10 parasites cleanse, then to diagnose the presence of parasites in the feces.
If you do have worms, parasites cleanse may get them out, and if parasites are large enough, you will see them with your eyes.
Don't bother sending specimens to local laboratories, they are often useless.