Translucent Post larval Disease (TPD) in Shrimp: An Emerging Challenge for Hatchery Health Management

Translucent Post-larval Disease (TPD) has recently been found as a significant challenge to shrimp aquaculture especially on early post-larval stages of Penaeus vannamei. It is characterised by glass like transparent organism, pale hepatopancreas, empty digestive tract, weak swimming and massive mortality that may reach 60-90% in a short duration. TPD was first reported in China in late 2019 and has spread swiftly to other areas of the world that are the biggest shrimp producers in Asia and other cases that were reported recently confirm that TPD is not limited only in China and is a major global biosecurity threat. TPD is caused by hypervirulent strains of Vibrio parahaemolyticus, which do not produce AHPND related toxins but have new virulence factors referred to as Vibrio high virulence proteins especially vhvp-2. Waterborne transmission and management related risk factors are also used to spread the disease through rapid transmission in hatcheries. There is still no specific treatment, but nowadays early diagnosis is important to reduce its effects as well as the need to adhere to biosecurity and enhanced hatchery management practices.