In a recent edition of Dorland's "American Illustrated Medical Dictionary"a trombidiosis, or trombidiiasis, has been defined as "infestation with Trombidium (Leptus) irritans." Throughout most of the United States the mite causing the condition is called the "chigger," and in the south the same term has also been applied to the sand flea (Pulex penetrans). Indeed, the same dictionary gives two definitions of the word chigger:
1. The Sarcopsylla (Dermatophilus, Tunga) penetrans, a sand flea of tropical regions: it often burrows in the hands and feet, causing great distress, and sometimes having even a fatal result.
2. A harvest mite, Leptus (Trombicula) irritans, of the southern United States, which sometimes becomes an annoying semiparasite.
Ewing,49 of the United States Bureau of Entomology, is perhaps the greatest authority on this subject, and he adheres exclusively to this second definition. He applies the term chigger mites to the acarids
PARKHURST HJ. TROMBIDIOSIS (INFESTATION WITH CHIGGERS). Arch Derm Syphilol. 1937;35(6):1011–1036. doi:10.1001/archderm.1937.01470240003001