Endemic pruritus in a family of four proved to be caused by the "bite and run" habits of the Cheyletiella yasguri mites that lived on the family dog. The mystery was solved only after the 6-year-old daughter experienced an explosive attack of pruritic papules after taking a nap in the dog's sleeping box. Virtually invisible ectoparasites remain a common cause of endemic pruritus within families. Since these patients show no acarologic, clinical, or laboratory evidence for the cause of their itch, a good rule remains, cherchez le chien.
Shelley ED, Shelley WB, Pula JF, McDonald SG. The Diagnostic Challenge of Nonburrowing Mite BitesCheyletiella yasguri. JAMA. 1984;251(20):2690–2691. doi:10.1001/jama.1984.03340440048027