Las Bolitas Syndrome in Penaeus vannamei Hatcheries in Latin America

• Published in: Microorganisms (Basel) Vol. 12; no. 6; p. 1186
• Main Authors: Intriago, Pablo, Montiel, Bolivar, Valarezo, Mauricio, Romero, Xavier, Arteaga, Kelly, Cercado, Nicole, Burgos, Milena, Shinn, Andrew P, Montenegro, Alejandra, Medina, Andrés, Gallardo, Jennifer
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 12.06.2024; MDPI
• Subjects: Algae; Bacteria; bacterial infection; Degeneration; Epidemics; Ethanol; Fish hatcheries; Hatcheries; Health aspects; Hepatopancreas; hepatopancreas infection; Intestine; las bolitas syndrome; Lipids; Midgut; Mortality; Necrosis; Pathology; Penaeus vannamei; Polymerase chain reaction; post-larvae; Seawater; Sucrose; Vibrio; zoea; Ecuador; Latin America; Asia; hepatopancreas infection; zoea; bacterial infection; post-larvae; las bolitas syndrome
• ISSN: 2076-2607; 2076-2607
• DOI: 10.3390/microorganisms12061186

In September 2023, several hatcheries in Latin America experienced significant mortality rates, up to 90%, in zoea stage 2 of . 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 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 species at concentrations of 10 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 . 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 to develop effective mitigation strategies for hatchery operations.