Human Skin Parasites
A variety of invertebrates bite or feed on or in the human skin, including flies, fleas, bedbugs, lice, mites and ticks. [ link to the sites below ]
Download information on ticks: .pdf
With a few exceptions, including larvae of a few flies, scabies mites and hard ticks, all these parasites bite, feed quickly, and leave. All of these skin parasites leave tell tale signs, including itchy, round, red papules (swellings). The majority of the bites last about two weeks if left alone. If scratched (something that is hard to resist) the itchiness and swellings could last up to two months. In addition, human fingernails are loaded with bacteria and scratching often leads to infections.
If symptoms of itching and crawling sensations in the skin persist and no evidence of parasites can be found, then Delusional Parasitosis or Ekbom's Syndrome must be considered. A variety of causes have been suggested for these sensations, including parasitism by Collembola and Strepsiptera or the presence of organisms called Morgellons. "Morgellons" is a term used to describe what are purported to be fiber-like parasites of the skin, but after decades of detailed study there is no evidence of an unknown organism fitting this description. There is also no evidence that Collembola or Strepsiptera are biologically capable of parasitizing humans. However, there are quite a number of physiological, hormonal and neurological syndromes that will cause these symptoms.
Information in this site specifically addresses parasites found in North America. The reason for the distinction is that there are other skin parasites, particularly in tropical regions that are not discussed here.