Senior Environmental Scientist (Specialist) California Department of Fish and Wildlife Gold River, California
In 2013, sarcoptic mange, caused by Sarcoptes scabiei mites, was identified in a population of endangered San Joaquin kit fox (Vulpes macrotis mutica) in Bakersfield, California. In 2019, a smaller outbreak was observed in kit foxes in Taft, California. To determine if the Taft outbreak occurred as spillover from the Bakersfield outbreak and whether epidemic control efforts should involve not only kit foxes but also dogs (Canis lupus familiaris), coyotes (Canis latrans), and red foxes (Vulpes vulpes), we evaluated genotypes and gene flow among mites collected from each species. We used 10 Sarcoptes microsatellite markers (SARM) to perform molecular typing of 445 S. scabiei mites collected from 22 infested kit foxes, two dogs, five coyotes, and five red foxes from Bakersfield, Taft, and other cities. We identified 60 alleles across all SARM loci and found kit fox- and red fox-derived mites were highly monomorphic, while genetic variability was greatest in Bakersfield coyote- and dog derived mites. AMOVA analysis documented distinct mite populations unique to hosts with an overall FST of 0.467. The lowest FST was between Bakersfield and Taft kit fox-derived mites (FST = 0.038), and the largest genetic difference was between Ventura coyote-and Taft kit fox-derived mites (FST = 0.843). These results show a relationship between the Bakersfield and Taft kit fox mange outbreak, and demonstrate some Sarcoptes host specificity, suggesting that, although an inter-species spillover event likely initiated the kit fox mange outbreak, mite transmission is now primarily intraspecific.
