Shrimp acute hepatopancreatic necrosis disease (AHPND) is caused by virulent strains of Vibrio parahaemolyticus and related Vibrio species. AHPND-associated mortalities occur early in the production cycle, usually within 30 to 35 days of stocking, and because of this AHPND was initially referred to as early mortality syndrome (OIE, 2019).

There are a number of causal agents recognised for oyster diseases. Examples of major oyster diseases and their causal protozoan agents are: bonamiosis (Bonamia exitiosa, B. ostreae); marteiliosis (Marteilia refringens); perkinsosis (Perkinsus marinus, P. olseni). These oyster diseases are notifiable OIE-listed diseases and occur worldwide (OIE, 2019).