Arizona—Dr. Lightner Finds the Cause of EMS

On May 1, 2013, the Global Aquaculture Alliance (GAA) reported that Dr. Donald Lightner, the famed shrimp pathologist at the University of Arizona, had found the cause of early mortality syndrome (EMS), a disease that is costing the shrimp farming industry a billion dollars a year.

Lightner’s team found that EMS is caused by a unique strain of a relatively common bacterium, Vibrio parahaemolyticus, that is infected by a virus known as a phage, which causes it to release a potent toxin. The bacterium is transmitted orally, colonizes the shrimp gastrointestinal tract and then produces a toxin that causes tissue destruction and dysfunction of the hepatopancreas, the shrimp’s digestive organ.

Research continues on the development of diagnostic tests for rapid detection of EMS that will enable improved management of hatcheries and ponds. It will also enable a better evaluation of the risks associated with importation of frozen shrimp or other products from countries affected by EMS.

Some countries have implemented policies that restrict the importation of frozen shrimp or other products from EMS-affected countries. Lightner said frozen shrimp likely pose a low risk for contamination of wild shrimp or the environment because EMS-infected shrimp are typically very small and do not enter international commerce. Also, his repeated attempts to transmit the disease using frozen tissue were unsuccessful.

In an effort to learn from past epidemics and improve future policy, the World Bank and the Responsible Aquaculture Foundation, a charitable education and training organization founded by the Global Aquaculture Alliance, initiated a case study on EMS in Vietnam in July 2012. Its purpose is to investigate the introduction, transmission and impacts of EMS, and recommend management measures for the public and private sectors.

Thanks to: www.shrimpnews.com