Bivalves are important members of coastal ecosystems where, through filter-feeding, they remove particulate nitrogen and other substances enhancing water quality, and can form “reefs” that provide habitats for a myriad of organisms. Oysters and clams are often challenged by protozoan parasites, including Perkinsus species. Perkinsus spp., causative of “Dermo” disease, can lead to mass mortalities of farmed and wild bivalve populations and hence have important detrimental ecological and economic consequences. Most of the studies aimed to understand and intervene against Dermo have centered in a game of two: protozoan parasite and bivalve host. We have found and isolated persistent viruses that propagate in the nucleus of trophozoites of both P. marinus TXsc ATCC# 50983 and P. olseni ALG-1 ATCC# 50984. The discovery of these 40-50 nm viruses adds a new dimension to the investigation and management of Dermo disease. In addition to transmission electron microscopy ultrastructural analysis we are performing genomic characterization including full genome sequencing. Perkinsus virulence factors fall within three non-mutually exclusive groups: (i) Cell propagation and differentiation; (ii) Protection against the bivalves immune response; (iii) Nutrient uptake from the bivalve host, via enzymatic break down of host tissues into transportable components. Interestingly, the role of viral infection has not yet been investigated as a virulence factor of Perkinsus spp. Recent studies have reported that viruses of protozoan parasites of vertebrate/human hosts, Trichomonas and Leishmania, are not infectious for, but have pathologic consequences to the protozoan’s hosts by enhancing the mucosal inflammatory reaction of the innate immune system to detrimental levels. Proving viral infection of Perkinsus spp. represents a paradigm shift in our thinking about Perkinsus spp. ecology and virulence toward their bivalve hosts. Furthermore, it opens the door to new approaches for management and intervention against the disease-causing agent.