<abstract xmlns="http://www.w3.org/1999/xhtml"><p>Aquaculture of tilapia is a new research venture in India. With intensification in farming practices, tilapia are increasingly susceptible to bacterial infections. This article describes the isolation and identification of pathogenic bacteria from cultured monosex Nile tilapia, <italic>Oreochromis niloticus</italic> (L.), that experienced moderate to severe mortalities in West Bengal, India between September and August 2014 and histopathological alterations in various organs. Gram-positive diplococci, identified as <italic>Streptococcus agalactiae</italic> with Streptococcus identification kits and 16S rDNA sequencing analysis, were isolated from the brain, operculum, and kidney. Other bacteria from the kidney were identified as <italic>Aeromonas sobria</italic>, <italic>A. caviae, Klebsiella pneumoniae</italic> ssp. <italic>pneumoniae</italic>, <italic>Escherichia coli</italic>, and <italic>Enterobacter cloacae</italic>. <italic>Staphylococcus epidermis</italic> was isolated from opercular hemorrhages. Histological sections of the infected tilapia brain revealed meningoencephalitis and granulomatous lesions. Sections from other organs indicated congestion, hemorrhagic and hyperplastic cells, necrosis, vacuolation, hemosiderin deposition, hypertrophic nuclei, melanomacrophage aggregation, and ruptured veins. This report is the first description of <italic>S. agalactiae</italic> as a primary pathogen causing meningoencephalitis in cultured tilapia in India.</p></abstract>

Aquaculture of tilapia is a new research venture in India. With intensification in farming practices, tilapia are increasingly susceptible to bacterial infections. This article describes the isolation and identification of pathogenic bacteria from cultured monosex Nile tilapia, Oreochromis niloticus (L.), that experienced moderate to severe mortalities in West Bengal, India between September and August 2014 and histopathological alterations in various organs. Gram-positive diplococci, identified as Streptococcus agalactiae with Streptococcus identification kits and 16S rDNA sequencing analysis, were isolated from the brain, operculum, and kidney. Other bacteria from the kidney were identified as Aeromonas sobria, A. caviae, Klebsiella pneumoniae ssp. pneumoniae, Escherichia coli, and Enterobacter cloacae. Staphylococcus epidermis was isolated from opercular hemorrhages. Histological sections of the infected tilapia brain revealed meningoencephalitis and granulomatous lesions. Sections from other organs indicated congestion, hemorrhagic and hyperplastic cells, necrosis, vacuolation, hemosiderin deposition, hypertrophic nuclei, melanomacrophage aggregation, and ruptured veins. This report is the first description of S. agalactiae as a primary pathogen causing meningoencephalitis in cultured tilapia in India.

Meningoencephalitis in farmed monosex Nile tilapia (<italic>Oreochromis niloticus</italic> L.) caused by <italic>Streptococcus agalactiae</italic>

Department of Aquatic Animal Health, Faculty of Fishery Sciences

West Bengal University of Animal and Fishery Sciences

Fisheries & Aquatic Life

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Meningoencephalitis in farmed monosex Nile tilapia ( L.) caused by 

Aquaculture of tilapia is a new research venture in India. With intensification in farming practices, tilapia are increasingly susceptible to bacterial...

Meningoencephalitis in farmed monosex Nile tilapia (Oreochromis niloticus L.) caused by Streptococcus agalactiae

Published Online: Nov 28, 2017

Page range: 187 - 200

Received: Mar 13, 2016

Accepted: Aug 01, 2017

DOI: https://doi.org/10.1515/aopf-2017-0018

Keywords
Monosex tilapia, Meningoencephalitis, Granulomatous lesions

© 2017 Archives of Polish Fisheries

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Meningoencephalitis in farmed monosex Nile tilapia (Oreochromis niloticus L.) caused by Streptococcus agalactiae

Published Online: Nov 28, 2017

Page range: 187 - 200

Received: Mar 13, 2016

Accepted: Aug 01, 2017

DOI: https://doi.org/10.1515/aopf-2017-0018

KeywordsMonosex tilapia, Meningoencephalitis, Granulomatous lesions

© 2017 Archives of Polish Fisheries

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Keywords
Monosex tilapia, Meningoencephalitis, Granulomatous lesions