RESPONSES OF RED FOXES TO FIRST AND 2ND INFECTION WITH SARCOPTES-SCABIEI

The clinical response of red foxes (Vulpes vulpes) to the mange mite, Sarcoptes scabiei, was characterized by infection of five, 4-mo-old re d foxes with S. scabiei originally isolated from a wild red fox. The i nfected foxes and three uninfected control foxes were monitored with w eekly complete blood counts and biweekly serum chemistry profiles, hyp ersensitivity tests, and evaluation of skin biopsies. After 7 wk, the fetes were treated and hela free of infection fur 2 mo. Six foxes, thr ee previously infected and three with no history of exposure, were the n infected with die same isolate of S. scabiei and followed for anothe r 7 wk; two additional previously infected foxes were held as treatmen t controls, and two foxes with no history of exposure as naive control s, All infected foxes developed significant immediate (Type I) hyperse nsitivity reactions to a S. scabiei mite extract within 2 wk of exposu re and maintained this reaction as long as 4 mo after clearance of mit es. Pronounced mast cell hyperplasia and infiltration with eosinophils were the earliest inflammatory cell responses noted in biopsy samples from infected foxes and were maintained throughout infection. Infecte d foxes also showed significant increases in white blood cell counts, due primarily tu increases in numbers of circulating neutrophils and e osinophils. Clinical response, severity of disease, and relative numbe rs of mites per cm(2) of skin of previously infected foxes and foxes u ndergoing their first infection did not differ. These results show tha t red foxes develop strong immediate hypersensitivity reactions to S. scabiei but, under our experimental conditions, did not exhibit resist ance to reinfection.