This Virginia SeaGrant (PDF) document features details of a study regarding QPX (Quahog Parasite Unknown), a disease-causing parasites in hard shell clams. The 3-year study indicates that clam strains of Mercenaria mencernaria produced from brood (hatchery) stocks in South Carolina and Florida are more susceptible to QPX than those from Virginia, New Jersey, and Massachusetts. These results indicate that growers should consider the geographic origin of clam seed as an important component of their QPX disease avoidance and management strategies.