Mice are much more commonly infested than are rats. Consequently, hairless mice are not susceptible. Life cycles require roughly 3 weeks for completion. Transmission is via direct contact. Once a facility is infested, eradication of the parasites is achievable but labor-intensive.
Clinical signs vary in severity depending upon host factors and mite species.
C57BL and related strains are most susceptible to severe disease, due to overexuberant type 1 hypersensitivity reactions. Lesions are most common on the dorsum, primarily on the back of the neck and interscapular region. Pathologic changes include hyperkeratosis, erythema, mast cell infiltration, ulcerative dermatitis, splenic lymphoid and lymph node hyperplasia, and eventual secondary amyloidosis. These immunologic changes are consistent with a Th2-type response, with marked systemic consequences.