Thirteen stool suspensions with varying amounts of inhibitors were spiked with intact CoxB3 virus at a concentration adjusted to yield a Ct equivalent to that of the MS2. These spiked suspensions were re-extracted in parallel by all four methods. With few exceptions, the extent of inhibition of enterovirus rRT-PCR was similar to that for inhibition of MS2 rRT-PCR (Fig. 3) . The number of samples with $6 Ct inhibition in MS2 rRT-PCR, that also had .6 Ct inhibition of enterovirus rRT-PCR, was 10/10 (100%), 9/9 (100%), 6/7 (85.7%), and 4/4 (100%) for Protocols A, B, C, and D, respectively.