Molecular detection of Enterocytozoon hepatopenaei and Vibrio parahaemolyticus-associated acute hepatopancreatic necrosis disease in Southeast Asian Penaeus vannamei shrimp imported into Korea

Sixty batches of white leg shrimp (Penaeus vannamei, 40-50 shrimp per batch) imported from multiple countries, including Vietnam, Indonesia, Malaysia, and Peru were collected from fishery markets in South Korea. Five shrimp were randomly selected from each batch, the hepatopancreases of shrimp were collected, and samples from each batch were pooled and analyzed via PCR. Examination by qPCR indicated that the shrimp were infected by two emerging pathogens, Enterocytozoon hepatopenaei (EHP) and Vibrio parahaemolyticus carrying pirA and pirB toxins, which are associated with acute hepatopancreatic necrosis disease (Vp(AHPND)). Specifically, EHP was detected in the shrimp imported from Vietnam and Indonesia (17/60 samples, 28%) and Vp(AHPND) was detected in the shrimp imported from Vietnam (1/60, 2%). One sample highly infected with EHP (C-t = 20.86 +/- 1.47, corresponding to the copy number of 8.5 x 10(5)-5.2 x 10(6)) was also infected with Vp(AHPND) (C-t = 29.36 +/- 0.25, corresponding to the copy number of 2.5 x 10(3)-3.4 x 10(3)). These results indicate that EHP and Vp(AHPND), which are not currently listed as quarantine-required shrimp pathogens in Korea, can be introduced to Korea through shrimp importing activities and may pose a potential threat to Korean shrimp culture industry. Greater awareness regarding importing of diseased shrimps, and subsequent enforcement of quarantine policies relating to these pathogens are required to ensure that South Korea remains EHP- and Vp(AHPND)-free.