TY - JOUR
T1 - First identification of Francisella noatunensis subsp. orientalis causing mortality in mexican tilapia Oreochromis spp
AU - Ortega, Cesar
AU - Mancera, Gerardo
AU - Enríquez, Ricardo
AU - Vargas, Augusto
AU - Martínez, Simón
AU - Fajardo, Raúl
AU - Avendaño-Herrera, Ruben
AU - Navarrete, María José
AU - Romero, Alex
N1 - Publisher Copyright:
© Inter-Research 2016.
PY - 2016/8/9
Y1 - 2016/8/9
N2 - Francisellosis, an emerging disease in tilapia Oreochromis spp., is caused by the facultative, intracellular bacterium Francisella noatunensis subsp. orientalis, which is present in various countries where tilapia farming is commercially important. We confirmed the presence of francisellosis in Mexican tilapia cultures in association with an outbreak during the second semester of 2012. Broodstock fish presented a mortality rate of approximately 40%, and disease was characterized by histologically classified granulomas, or whitish nodules, in different organs, mainly the spleen and kidney. Through DNA obtained from infected tissue and pure cultures in a cysteine heart medium supplemented with hemoglobin, F. noatunensis subsp. orientalis was initially confirmed through the amplification and analysis of the 16S rRNA gene and the internal transcribed spacer region. Phylogenetic analysis of these genes demonstrated close similarity with previously reported F. noatunensis subsp. orientalis sequences obtained from nfected tilapia from various countries. The identification of this subspecies as the causative agent of the outbreak was confirmed using the iglC gene as a target sequence, which showed 99.5% identity to 2 F. noatunensis subsp. orientalis strains (Ethime-1 and Toba04). These findings represent the first documented occurrence of francisellosis in Mexican tilapia cultures, which highlights the importance of establishing preventative measures to minimize the spread of this disease within the Mexican aqua - culture industry.
AB - Francisellosis, an emerging disease in tilapia Oreochromis spp., is caused by the facultative, intracellular bacterium Francisella noatunensis subsp. orientalis, which is present in various countries where tilapia farming is commercially important. We confirmed the presence of francisellosis in Mexican tilapia cultures in association with an outbreak during the second semester of 2012. Broodstock fish presented a mortality rate of approximately 40%, and disease was characterized by histologically classified granulomas, or whitish nodules, in different organs, mainly the spleen and kidney. Through DNA obtained from infected tissue and pure cultures in a cysteine heart medium supplemented with hemoglobin, F. noatunensis subsp. orientalis was initially confirmed through the amplification and analysis of the 16S rRNA gene and the internal transcribed spacer region. Phylogenetic analysis of these genes demonstrated close similarity with previously reported F. noatunensis subsp. orientalis sequences obtained from nfected tilapia from various countries. The identification of this subspecies as the causative agent of the outbreak was confirmed using the iglC gene as a target sequence, which showed 99.5% identity to 2 F. noatunensis subsp. orientalis strains (Ethime-1 and Toba04). These findings represent the first documented occurrence of francisellosis in Mexican tilapia cultures, which highlights the importance of establishing preventative measures to minimize the spread of this disease within the Mexican aqua - culture industry.
KW - Francisellosis
KW - Freshwater aquaculture
KW - Mexico
KW - Tilapia
UR - http://www.scopus.com/inward/record.url?scp=84981336648&partnerID=8YFLogxK
U2 - 10.3354/dao02999
DO - 10.3354/dao02999
M3 - Article
AN - SCOPUS:84981336648
SN - 0177-5103
VL - 120
SP - 205
EP - 215
JO - Diseases of Aquatic Organisms
JF - Diseases of Aquatic Organisms
IS - 3
ER -