Journal of Marine Biology

White Spot Syndrome Virus (WSSV) is regarded as one of the most important viral and economically devastating agents in the shrimp aquaculture industry. This study aimed to evaluate the severity of lesions associated with WSSV infection across different tissues of Litopenaeus vannamei. To this end, infected shrimp were sampled, and following tissue sectioning and hematoxylin–eosin staining, microscopic examinations were performed. The Severity of Infection Index was assessed on a 0–4 grading scale. The results indicated that the highest levels of infection were observed in gill tissue (ROI = 78.9%) and lymphoid tissue (ROI = 3.67%), whereas the hepatopancreas and muscle tissues exhibited the lowest lesion severity. These findings underscore the central role of gill tissue in the clinical manifestation of the disease and highlight its importance for health monitoring in farmed shrimp. The application of a lesion severity index may serve as an effective tool for assessing pathological status and improving health management practices in shrimp aquaculture facilities.