Advanced Pathogen Monitoring in Penaeus vannamei from Three Latin American Regions: Passive Surveillance Part 2
Pablo Intriago1,2, Bolivar Montiel2, Mauricio Valarezo2
1South Florida Farming Corp., 13811 Old Sheridan St, Southwest Ranches, FL 33330, USA.
Abstract:
This study presents the second phase of a year-long investigation comparing multiple PCR analyses and histological examinations to confirm the presence of characteristic lesions of each pathogen 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 Penaeus 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 lesions 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. Histopathological analysis indicated that shrimp typically presented coinfections, such as WzSV8, Decapod hepanhamaparvovirus (DHPV), chronic midgut inflammation, and tubule distension/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.
Insights
This study found bacterial infections dominated shrimp pathology across Latin America, often alongside Wenzhou shrimp virus 8 (WzSV8) and Decapod hepanhamaparvovirus (DHPV) coinfections. These findings highlight complex disease interactions in wild and farmed shrimp populations.
Area of Science:
- Aquatic animal health
- Veterinary pathology
- Molecular diagnostics
Background:
- PCR and histological analyses are crucial for identifying shrimp pathogens.
- Previous studies focused on wild Penaeus vannamei, necessitating broader species and geographic scope.
- Understanding pathogen prevalence and co-infection dynamics is vital for shrimp aquaculture sustainability.
Purpose of the Study:
- To compare PCR and histological findings for over 20 DNA/RNA viruses, bacteria, and microsporidia in Latin American shrimp.
- To investigate pathogen presence in wild Penaeus stylirostris and Penaeus monodon, alongside Penaeus vannamei.
- To assess the correlation between PCR results, viable pathogens, and characteristic histopathological lesions.
Main Methods:
- Year-long investigation involving multiple PCR assays and histological examinations.
- Sampling of wild Penaeus vannamei, Penaeus stylirostris, and Penaeus monodon from three Latin American regions.
- Targeted detection of over 20 viral, bacterial, and microsporidian agents.
Main Results:
- Wenzhou shrimp virus 8 (WzSV8) was prevalent in both wild and farmed shrimp across all regions.
- Common coinfections included WzSV8, Decapod hepanhamaparvovirus (DHPV), and signs consistent with bacterial toxin exposure.
- Bacterial infections were the predominant pathology observed, with bacterial muscle necrosis noted in some areas.
- WzSV8 and DHPV were postulated to infect hepatopancreatic, cecal, and intestinal cells.
Conclusions:
- Bacterial infections represent the primary pathological concern in the studied shrimp populations.
- Coinfections involving WzSV8 and DHPV are common and contribute to disease complexity.
- The study underscores the importance of integrating molecular and histopathological data for accurate shrimp disease diagnosis.
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