Regional Prevalence and Molecular Detection of Enterocytozoon hepatopenaei in Coastal Shellfish from Korea

EHP causes hepatopancreatic microsporidiosis in shrimp, leading to growth retardation without notable mortality. To examine potential environmental carriers, farmed bivalves were collected near shrimp ponds in Korea and screened for EHP using nested PCR targeting the spore-wall-protein gene. DNA of EHP was mainly detected in gill and digestive tissues of oysters, scallops, mussels, and clams. Histopathology after 24 h immersion exposure confirmed spores within the intestinal epithelium of clams, indicating short-term invasion potential. These results suggest that bivalves can retain and mechanically transfer EHP spores through shared seawater between shrimp farms and surrounding areas. Considering the environmental persistence of EHP, continuous surveillance of local invertebrates is recommended to reduce the risk of EHP introduction and further spread in aquaculture systems.