Intriago, Pablo, Montiel, Bolivar, Valarezo, Mauricio, Romero, Xavier, Arteaga, Kelly, Cercado, Nicole, Burgos, Milena, Shinn, Andrew P., Montenegro, Alejandra, Medina, Andrés, and Gallardo, Jennifer (2024) Las Bolitas Syndrome in Penaeus vannamei Hatcheries in Latin America. Microorganisms, 12. 1186.

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Abstract

In September 2023, several hatcheries in Latin America experienced significant mortality rates, up to 90%, in zoea stage 2 of Penaeus vannamei. Observations of fresh mounts revealed structures resembling lipid droplets, similar to those seen in a condition known as “las bolitas syndrome”. Routine histopathological examinations identified detached cells and tissues in the digestive tracts of affected zoea, contrasting with the typical algal cell contents seen in healthy zoea. Polymerase chain reaction (PCR) testing for over 20 known shrimp pathogens indicated minimal differences between diseased and healthy batches. Both groups tested negative for acute hepatopancreatic necrosis disease (AHPND) but positive for Vibrio species and Rickettsia-like bacteria in the diseased samples. Histological analyses of the affected zoea revealed characteristic tissue degeneration in the hepatopancreas, forming spheres that eventually migrated into the upper gut, midgut, and midgut caeca, a pathology identified as bolitas syndrome (BS). Microbiological assessments revealed Vibrio species at concentrations of 106 CFU zoea/g in affected zoea, approximately two orders of magnitude higher than in healthy zoea. Bacterial isolation from both healthy and BS-affected zoea on thiosulphate–citrate–bile salts–sucrose (TCBS) agar and CHROMagar™ (Paris, France), followed by identification using API 20E, identified six strains of Vibrio alginolyticus. Despite similarities to “las bolitas syndrome” in fresh mounts, distinct histopathological differences were noted, particularly the presence of sloughed cells in the intestines and variations in hepatopancreatic lobes. This study highlights the critical need for further research to fully understand the etiology and pathology of bolitas syndrome in zoea stage 2 of P. vannamei to develop effective mitigation strategies for hatchery operations.

Item ID:	85813
Item Type:	Article (Research - C1)
ISSN:	2076-2607
Copyright Information:	© 2024 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
Date Deposited:	12 Jun 2025 02:02
FoR Codes:	30 AGRICULTURAL, VETERINARY AND FOOD SCIENCES > 3005 Fisheries sciences > 300503 Fish pests and diseases @ 50% 31 BIOLOGICAL SCIENCES > 3107 Microbiology > 310701 Bacteriology @ 50%
SEO Codes:	10 ANIMAL PRODUCTION AND ANIMAL PRIMARY PRODUCTS > 1002 Fisheries - aquaculture > 100205 Aquaculture prawns @ 100%
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