Mortality in pond-cultured shrimp Penaeus monodon in the Philippines associated with Vibrio harveyi and white spot syndrome virus

Abstract

Heavy mortalities were observed among pond-cultured Penaeus monodon in the provinces of Bohol, Misamis Occidental, Lanao del Norte and Zamboanga del Sur, Philippines. Vibrio harveyi was isolated purely from the hepatopancreas and lymphoid organs of affected shrimp and histopathological observations indicated a severe bacterial infection in the shrimp. Majority of the samples gave negative results in the one-step PCR for the detection of white spot syndrome virus (WSSV). However, nested PCR produced amplicons specific for WSSV DNA from most of the shrimp tested. These results suggest that shrimp were infected dually with V. harveyi and WSSV, but the major causative agent of the present mortalities was V. harveyi.