AHPN inferences based on behavior of Vibrio bacteria
Vibrio parahaemolyticus, the pathogen associated with acute hepatopancreatic necrosis (AHPN), has both toxic and benign strains. It inhabits the stomachs of shrimp in a biofilm, which protects it from antibiotics and other treatments. As with V. cholera, V. parahaemolyticus tolerates a range of salinities, pH and temperatures. Both species readily piggyback on marine plankton and may be spread by ocean currents. Virulent V. parahaemolyticus has also been spread by infected broodstock and postlarvae. The etiologic agent of AHPN occupies many niches.
Vibrio is a genus of Gram-negative bacteria that inhabit most aquatic ecosystems, including freshwater. As of late 2013, there are at least 98 recognized species, with many more candidates. Vibrios serve critical functions in the recycling of nutrients, including polymeric n-acetylglucosamine, a molecule commonly known as chitin, the primary structural component of the exoskeletons of shrimp and other arthropods.
Most vibrios are benign. Many have the ability to degrade chitin by the production of chitinases and readily attach to chitinous invertebrates. They are also often associated with algal and zooplankton species, which provide important means of transport within aquatic environments and contribute to their ecological stability.