Acute Hepatopancreatic Necrosis Disease (AHPND) is caused by Vibrio parahaemolyticus , Vibrio harveyi , and Vibrio campbellii carrying the AHPND plasmid (pVA ) and toxin genes. These pathogenic bacteria proliferate in aquaculture water or the shrimp’s digestive tract, producing PirA /B toxins that lead to hepatopancreatic necrosis and subsequent mortality.
Our previous experiments have shown that when the concentration of pathogenic V. parahaemolyticus in water reaches 104 cfu /ml, it does not cause immediate death in cultured shrimp, and no signs of AHPND are observed within two weeks. However, when the concentration of pathogenic V. parahaemolyticus in water reaches 106 cfu /ml, the mortality rate reaches 60% within a week. Feeding shrimp with pathogenic Vibrio-infused die shrimp (5x107 cfu /g) results in AHPND symptoms within 24 hours, and a 50% mortality rate within a week.
The results suggest that shrimp ingesting dead shrimp containing pathogenic Vibrio have an increased mortality rate and a faster onset of AHPND infection compared to those not directly ingesting them. This study preliminarily indicates that healthy shrimp ingesting infected dead shrimp in the environment is a significant factor in causing AHPND and accelerating disease onset. Reducing the intake of infected dead shrimp in the environment can lower the occurrence of infections.
Therefore, for the prevention and treatment of vibriosis, it is necessary to start from the following points:
3. Effectively reduce the concentration of Vibrio in shrimp bodies. Regular supplementation of intestinal probiotics to effectively reduce the concentration of Vibrio in shrimp bodies.