Frequency distribution of coyote serum samples that had positive titers in indirect immunofluorescence antibody assay for spotted fever group rickettsia. Samples were taken in April and May of 2016 and 2017. The natural drop in frequency of positive results above the endpoint titer (128) was used to establish the adjusted cutoff titer of 256. The dark-gray bars indicate positive titers above the adjusted cutoff. Titers are expressed as the reciprocal of the highest dilution factor that produced a positive result.