In 2010, Early Mortality Syndrome (EMS), a new shrimp disease, appeared on shrimp farms in southern China and on China’s Hainan Island. By early 2011, it spread to Vietnam and Malaysia.
The disease appears within 20 to 30 days after stocking. Giant tiger shrimp, Penaeus monodon, and Western white shrimp, P. vannamei, are affected. Diseased shrimp become lethargic, stop eating and mortalities approach 100% in severely affected ponds. The hepatopancreas shrinks and has whitish and black streaks. Other signs include a soft, generally darker shell and mottling of the carapace.
In samples of shrimp preserved for histology, the effects of EMS appear to be limited to the hepatopancreas. The degenerative pathology of the hepatopancreas suggests a toxic etiology. Similar lesions have been reported in the hepatopancreases of shrimp exposed to aflatoxin B1 (a toxin produced by many species of the Aspergillus fungus) and benomyl (a mitosis inhibitor).
Studies to determine the cause of EMS have not been successful. Researchers have ruled out commercial feeds used on shrimp farms where EMS occurred and a crustacide commonly used in the region to kill whitespot vectors. Frozen samples of shrimp with EMS did not infect other shrimp. To date, the researchers have not been able to experimentally induced lesions of the hepatopancreas consistent with those observed in shrimp with EMS.
Source: The Global Aquaculture Advocate (The Global Magazine for Farmed Seafood). Editor, Darryl Jory ([email protected]). Early Mortality Syndrome Affects Shrimp in Asia. Donald V. Lightner ([email protected], OIE Reference Laboratory for Shrimp Diseases, Department of Veterinary Science and Microbiology, University of Arizona, Tucson, Arizona 85721, USA), R.M. Redman, C.R. Pantoja, B.L. Noble and Loc Tran (Department of Veterinary Science and Microbiology, University of Arizona). Volume 15, Issue 1, Page 40, January/February 2012.
Arizona–University of Arizona’s Dr. Donald Lightner Describes New Shrimp Disease
January 9, 2012 By