Haplosporidium nelsoni (MSX) and Perkinsus marinus (dermo) co-occur in Crassostrea virginica, overlapping in seasonal patterns of infection and sharing host tissue space. We examined the prevalence and intensity of these two common microparasites over time to better understand multi-pathogen interactions and patterns of co-infection. Diagnostic data f rom 2007-2020 for individual oysters across the Virginia portion of the Chesapeake Bay were analyzed to determine whether any correlations occur between parasite prevalence and intensity. We found a weak positive association between advanced infections of dermo and higher intensity MSX infections in individual oysters in the Chesapeake Bay, but an opposite trend in co-infected oysters from the seaside Eastern Shore. Analyses of sample prevalences of both parasites from 1989-2019 revealed a positive correlation between MSX and dermo prevalences . Collectively, these data do not point to strong contemporary interactions between the two pathogens infecting oyster hosts. Interestingly, however, the sample prevalence analyses revealed eight outlying data points , all of which were high MSX-low dermo prevalence samples from before 2007 (marked by triangles in Fig. 1) . Notably, these were all from reefs of low oyster abundance, a suggestion that MSX may have benefitted at times from the decrease in dermo caused by low host density unfavorable to directly transmissible P. marinus . While contemporary interactions between the two pathogens would appear to be modest at best, these data do suggest that the intensification of dermo since the 1980s may have historically suppressed MSX infections, and that this multiparasite-host system may have reached something of a stable state after earlier decades of more intense interaction and coevolution.