Larvae migrans -- 'dog hookworm'. They come from dogs, live in the sand, enter humans or animals via the skin,cause an itchy rash that is characterized by a track as the worm travels under the skin, are microscopic, and are easily treated.
it is SELF-LIMITING... not easily treated. In fact, most references say no treatment really works.
links :
http://www.emedicine.com/derm/topic91.htmhttp://www.dermnetnz.org/arthropods/larva-migrans.htmlhttp://en.wikipedia.org/wiki/Cutaneous_larva_migrans