Hi, What are the symptoms of a human parastic infection on the tongue? For example, the patient has had a half-an-inch wide white mouth ulcer near the tip of his tongue, which has caused him much irritation and occasional pain for most of the last three years. It has never really gone away, but has not spread to any other part of the tongue or mouth. Yeast pills, acyclovir , and mouth washes have not had any affect on it. Nor has peroxide , which seems to make it all the more irritated. Since it has been on his tongue for over three years now, baffling doctors (except for the latest physician who did a biopsy and is awaiting the results) do you think it could be some sort of parastic infection. Or does it seem more like the precursor to, say. mouth cancer or such? Any info would be greatly appreciated.