Passive surveillance for shrimp pathogens in Penaeus vannamei submitted from 3 regions of Latin America

Abstract

Multiple PCR analyses were conducted to broaden the search spectrum for shrimp pathogens, revealing some pathogens without histological lesions. This underscores the importance of selecting appropriate primers for obtaining reliable results. Notably, there was significant variability among primers, emphasizing the need for seasonal and regional assessment to optimize primer selection. It's crucial to understand that a positive PCR test result alone doesn't confirm the presence of a viable pathogen or a disease state. Therefore, histological analysis was employed to confirm the presence of characteristic lesions for each pathogen. Overall, most shrimp exhibited coinfections, including WzSV8, DHPV, chronic midgut inflammation, and tubule distension/epithelial atrophy consistent with AHPND. Additionally, non-EHP-microsporidia, striated muscle necrosis in the abdomen, and gregarines in the hindgut caecum were observed. The presence of spheroids in the lymphoid organ might indicate host responses to often unidentified causes.