Abstract:In order to clarify the shrimp disease occurred currently in the shrimp farms, shrimp pathogens including vibrio, Enterocytozoon hepatopenaei (EHP) and four viral pathogens(WSSV、IMNV、CMNV and IHHNV) were detected using molecular biological detect methods under a regular sampling pattern, meanwhile the concentration of ammonia nitrogen and nitrogenous nitrogen in water body were also detected. The results showed that the main pathogens in the shrimp farm comprised various pathogenic vibrio and EHP. However the shrimp virus WSSV、IMNV、CMNV and IHHNV were not detected. The vibrio species isolated and identified reached 16 totally, and the main species were Vibrio parahaemolyticus, V. alginolyticus, V. owensii, V. vulnificus, V. harveyi. Furthermore the V. parahaemolyticus that could cause acute hepatopancreatic necrosis disease (VAHPND) was found out. The concentration of ammonia nitrogen and nitrate nitrogen in the indoor pond reaching (3.5±2.0) mg/L and (8.2±0.7) mg/L, were significantly higher than that in the outdoor pond respectively (P < 0.05) in the medium-term (July 24) of crop cycle. The intensity of infection of VAHPND and EHP show a growing trend in the culture period. In the seven ponds monitored, the ponds indoor had a higher incidence rate (100%), while the ponds outdoor had a lower incidence rate (25%). The results indicated that shrimp disease onset in the pond indoor might be caused by the infection of various vibrio and EHP, also the higher stocking density, higher concentration of the ammonia nitrogen and nitrate nitrogen in the water body played a synergy role in outbreak of shrimp disease. The results of this study could provide theoretical support and scientific data for the prevention and control of shrimp diseases.
