The Collaborative International Dictionary of English v.0.48:

Chigoe \Chig"oe\, Chigre \Chig"re\, n. [Cf. F. chigue, perh. fr.
   Catalan chic small, Sp. chico; or of Peruvian origin.]
   (Zool.)
   A species of flea (Tunga penetrans, formerly Pulex
   penetrans), common in the West Indies and South America,
   which often attacks the feet or any exposed part of the human
   body, and burrowing beneath the skin produces great
   irritation. When the female is allowed to remain and breed,
   troublesome sores result, which are sometimes dangerous. See
   Jigger. [Written also chegre, chegoe, chique,
   chigger, jigger.]
   [1913 Webster]

   Note: The name is sometimes erroneously given to certain
         mites or ticks having similar habits.
         [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

chigger \chigger\ n.
   1. a small tropical flea (Tunga penetrans, formerly Pulex
      penetrans); same as chigoe. [Also spelled chigre.]

   Syn: chigoe, chigoe flea, Tunga penetrans.
        [WordNet 1.5]

   2. a larval mite of the family Trombiculidae that sucks the
      blood of vertebrates including human beings, causing
      intense irritation, and serving to transmit several
      infectious diseases.

   Syn: harvest mite, jigger, redbug.
        [WordNet 1.5]