Integration of histopathology and molecular tools in shrimp health surveillance: A case study from Colombia

The present study assessed the added diagnostic value of histopathology in complementing molecular detection of World Organization for Animal Health-listed viral pathogens during Colombia's national shrimp health surveillance program.

Pooled samples of pleopods from 1,470 whiteleg shrimp Penaeus vannamei (5 animals/pool for a total of 294 pooled samples) were screened for white spot syndrome virus, Taura syndrome virus, and yellow head virus using standardized PCR/reverse transcription PCR assays in accordance with Instituto Colombiano Agropecuario protocols. A subset of 81 shrimp was taken for whole-body histopathology analysis following standardized protocols and a semiquantitative G0-G4 lesion grading scale. Lesions were classified by organ system, and histopathological findings were compared to molecular results.

All PCR assays were negative, with internal and external controls performing as expected. Using histopathology, lesions were identified in 77% of the shrimp examined, and lesions were primarily mild. Frequent findings included integumentary and gill colonization by Zoothamnium spp.; hepatopancreatic tubular necrosis with hemocytic granuloma-like reactions compatible with bacterial infection; intranuclear inclusion-like bodies, possibly of parvoviral origin; and focal myofiber necrosis, with organisms consistent with microsporidia. Autolysis was common but did not preclude lesion interpretation.

Histopathology provided diagnostic information that was not captured by targeted molecular assays, revealing subclinical, opportunistic, and nonviral processes relevant to shrimp health. Incorporating histopathology into routine surveillance programs enhances pathogen detection and strengthens health assessments to certify disease-free status of shrimp production systems, as recommended by the World Organization for Animal Health.