ISOLATION AND CHARACTERIZATION OF VIBRIO-DAMSELA INFECTIOUS FOR CULTURED SHRIMP IN TAIWAN

A Vibrio infection has been found to be associated with spontaneous mortality among cultured tiger shrimp (Penaeus monodon) in Taiwan. Affected shrimp display nonspecific signs, including poor growth rate, anorexia, rough shell, and milky musculature. Large numbers of short, curved bacterial rods were observed in the hepatopancreas, giving the infected tissue a pale and atrophic appearance. Melanized granulomatous ulcerations encapsulated by hemocytes and connective tissues in the hepatopancreas were seen by histopathological examination. Twelve isolates of Vibrio were isolated and examined for 47 characteristics based on their morphology, physiology, and biochemistry from March to October 1988. They were found to represent a homogeneous group of bacteria thought to belong to a single species. DNA relatedness to reference strain ATCC33539 confirmed that the isolates were V. damsela. Experimental infections in both anal intubation and intramuscular injection with V. damsela produced mortality in tiger shrimp, it was shown that 105 bacteria were aide to induce shrimp hepatopancreatitis and death using anal intubation. The hepatopancreatic tubules were necrotic, and cell debris was observed in the lumen. The melanized cells were also found around the foci and inflammatory sinuses were infiltrated with hemocytes. No death, however, existed in the group as a result of water-borne infection. This suggested that V. damsela was one of the etiological agents associated with shrimp mortality under stressed conditions. © 1993 Academic Press. All rights reserved.