Acaridae Incognito: The Case Of The Mighty Mite

Mites, arthropods of 0.1 to 1.0 mm in length, are common ectoparasites of animals and humans. Sarcoptes scabiei is the most familiar of the blood-sucking parasitic mites infesting humans. A mite found in skin samples scraped from a patient's pruritic rash is commonly assumed to be S. scabiei with no further identification of species deemed necessary. Several parasitic mites from animal hosts and many species of free-living mites, however, can also infest households and cause symptoms in household members. Our report deals mainly with less familiar household mite infestations, particularly those due to the ubiqui-tous free-living mites. Because therapy varies greatly depending on which mite species is caus-ing the infestation, the physician should make every effort to identify the mite accurately, which, as this case report shows, can be exceedingly difficult. Case Report A 22-month-old girl was seen by her family phy-sician in Houston with a 3-week history of a pruritic rash. The girl continuously and energeti-cally scratched the rash throughout the day. At night, the pruritus caused considerable distress and loss of sleep to her and to her parents. The rash had begun on the lateral lower legs, then had spread to the arms and entire body. It had worsened steadily despite the application of 1 percent hydrocortisone cream and 2 percent miconazole nitrate. Other family members had no symptoms. On physical examination, patches of excoriated papules were densely scattered over the body, excluding the scalp, palms, and soles. The patient's mother had several papules associated with linear burrow-like lesions on the forearm. A scraping of the mother's lesion revealed what ap-peared to be a mite extremity. The diagnosis o