This study was done to detect the epidemiology of the white spot syndrome virus and how to diagnose it by molecular tools. 200 cultured Litopenaus vannamei samples were collected seasonally and randomly from different localities in Egypt such as Damietta and Port Said governorates. Infected shrimp exhibited white spot lesions on the carapace and the external surface. Some cases revealed a generalized pink body color and red coloration of appendages (telson). The overall incidence of white spot disease among collected Litopenaeus vannamei was 11.5% and the seasonal prevalence was 0, 0, 6, and 40% in winter, spring, summer, and autumn respectively. Molecular diagnosis by conventional PCR with primers particularly for WSSV VP28 revealed an expected amplified result at 677 bp fragments using agarose gel electrophoresis. Confirmation of diagnosis was done by histopathological studies, which demonstrated nuclear basophilic inclusion bodies in the subcuticular cells and vacuolation, degeneration with disarrangement in the hepatopancreas of infected shrimp.  The current findings call for creating WSSV prevention strategies in white-leg shrimp, especially in seasons with moderate temperatures.