There are many different types of parasites, most of which are not common in the United States. One of the most common in the here is intestinal worms. There are different types of these types of parasites. Some cause anal itching while other cause weight loss
and vitamin deficiencies. The only type of worm infection I have seen in an otherwise healthy person was in a young boy who had itching around the anus at night. Another type of parasite that we see is Giardia. This is a parasite that lives in Mountain streams, but also contaminates foods in third world countries and causes diarrhea
. Other parasites can infect the brain, lungs, liver, or any pretty much any other organ.
Most parasitic infections do not cause only a rash, so I would guess that the symptoms you have described are probably not due to a parasitic infection. The parasites that live in us that we don't know about are uncommon.
If you are experiencing weight loss, diarrhea, intermittent fevers, or have done some exotic traveling recently, then I think you should be evaluated. Since it sounds like this is not the case, I suggest that you bring this issue up at your next visit with the primary care physician
. You can discuss measures to protect yourself against these infections.