The only analyses for 2007 were for September samples, when between-site differences in MSBB were evident (Fig.
There were no differences among strains for MSBB and MIBB (P > 0.
Comparisons of MSBB thresholds also revealed a strong location effect (Fig.
Closer examination of post-freshet dermo disease levels showed that log MSBB and log MIBB levels followed the salinity gradient and were distinctly different at all sites (P < 0.
Therefore, MSBB values below this threshold may reflect samples where the parasite may be present in many, or all, hosts, but where infections would remain undetected by standard methods, and prevalences would be scored as 0 (false negative).