Fleas burrowing in your toenails. Life is weird....
Chiggers are the skin lesions produced by the female flea of the species Tunga penetrans, mainly found in Central and tropical South America, as well as tropical Africa and India. Although the pig is the natural host for the flea, walking around barefoot in endemic areas can give a flea the wrong idea and will burrow in the victim's feets skin, often localized next to a toe nail.
The disease can be diagnosed by the appearance of itchy, painful and irritating nodules on the skin. When opened, the bloated, eggfilled body of the female flea can be seen. The insect should then be removed carefully via microsurgery, but sepsis or tetanus are a common ensueing problem.
As usual, the best advice is protective clothing, so a pair of shoes will avoid flea eggs in your toes, oh noder.
Dion R. Bell, Tropical Medicine, 4th Edition, Blackwell Sciences, 2000