Pathogen-host interactions were investigated with a simple 'host-pathogen-interaction' system, using as tentative criteria of interaction: increase in viral prevalence, increase in infection intensity, increase in mortality, and enhanced cyptopathic effects in exposed-infected shrimp as compared to control-infected shrimp. A large group of shrimp, 23.3 percent of which had light patent Baculovirus infections, was divided equally into two groups. One group was exposed to the chemical stressor Aroclor 1254 at 0.7 parts per billion for 35 days in flowing seawater. The other group was maintained as control in flowing seawater. Viral prevalence in exposed shrimp samples increased with time at a significantly greater rate than in control shrimp. Viral prevalence in Aroclor-exposed shrimp survivors was 75 percent after 35 days, whereas only 45.7 percent of control shrimp had patent viral infections. This finding suggests an interaction among the chemical stressor (Aroclor 1254), host, and virus. Nature or mechanism of the interaction has not been defined, but the shrimp-virus system shows promise for future bioassays to determine influence of low concentrations of pollutants on natural pathogen-host interactions.