Advanced Pathogen Monitoring in Penaeus vannamei from Three Latin American Regions: Passive Surveillance Part 2

This study presents the second phase of a year-long investigation comparing multiple PCR anal-yses and histological examinations to confirm the presence of characteristic lesions for each path-ogen in three different regions of Latin America. More than 20 agents, including DNA and RNA viruses, bacteria and microsporidia, have been targeted. In addition to wild P. vannamei, which was studied previously, samples of wild P. stylirostris and P. monodon were included. Notably, a positive PCR test result alone does not confirm the presence of a viable pathogen or a disease state. Similarly, positive PCR results do not necessarily correlate with the presence of histological le-sions characteristic of the targeted pathogen. Wenzhou shrimp virus 8 (WzSV8) was found to be widespread among shrimp in all regions, including both farm-raised and wild populations. Histo-pathological analysis indicated that shrimp typically presented coinfections, such as WzSV8, dec-apod hepanhamaparvovirus (DHPV), chronic midgut inflammation, and tubule disten-sion/epithelial atrophy, consistent with the toxicity of Pir A/B or another bacterial toxin. Bacterial muscle necrosis was also found in some regions. In general, bacterial infection was the dominant pathology in all three regions during the year. We also postulate that both WzSV8 and DHPV can infect not only hepatopancreatic cells but also cells in the ceca and intestine.