DETECTION OF THE CAUSATIVE BACTERIUM OF VIBRIOSIS IN KURUMA PRAWN, PENAEUS-JAPONICUS

A one-year field survey on the presence of Vibrio sp. PJ, the causative agent of vibriosis in kuruma prawn (Penaeus japonicus), was carried out in prawn farms in Hiroshima and Yamaguchi Prefectures by a conventional bacterial culture method. The result revealed that the pathogen has already been widely distributed in the prawn culture environment. The population of the pathogen increased both in prawns and in their environment with a rise in water temperature. Indirect fluorescent antibody technique (IFAT) was applied to smear specimens of the lymphoid organ of both experimentally and naturally infected kuruma prawns. This method was found effective as a rapid and reliable diagnostic method for the present disease, though the sensitivity was slightly lower than that of the culture method.