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Puerto Montt, Chile

Bastardo A.,University of Santiago de Compostela | Bohle H.,ADL Diagnostic Chile Ltd | Ravelo C.,Estacion de Investigaciones Hidrobiologicas de Guayana | Toranzo A.E.,University of Santiago de Compostela | Romalde J.L.,University of Santiago de Compostela
Diseases of Aquatic Organisms | Year: 2011

We investigated 11 strains of Yersinia ruckeri, the causative agent of enteric redmouth disease (ERM), that had been isolated from Atlantic salmon Salmo salar L. farmed in Chile and previously vaccinated against ERM. Phylogenetic analysis of the 16S rRNA gene sequences confirmed the identification of the salmon isolates as Y. ruckeri. A comparative analysis of the biochemical characteristics was made by means of traditional and commercial miniaturised methods. All studied isolates were motile and Tween 80 positive, and were identified as biotype 1. In addition, drug susceptibility tests determined high sensitivity to sulphamethoxazole/trimethroprim, oxytetracycline, ampicillin and enrofloxacin in all isolates. Serological assays showed the presence of O1a, O1b and O2b serotypes, with a predominance of the O1b serotype in 9 strains. Analysis of the lipopolysaccharide profiles and the correspondent immunoblot confirmed these results. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) of the outer membrane proteins revealed that all Chilean strains had profiles with a molecular weight range between 34 and 55 kDa, with 3 distinct groups based on differences in the major bands. Genotyping analyses by enterobacterial repetitive intergenic consensus (ERIC-) and repetitive extragenic palindromic (REP-)PCR techniques clearly indicated intraspecific genetic diversity among Chilean Y. ruckeri strains. © Inter-Research 2011. Source

Rozas M.,ADL Diagnostic Chile Ltd | Rozas M.,Austral University of Chile | Bohle H.,ADL Diagnostic Chile Ltd | Grothusen H.,ADL Diagnostic Chile Ltd | Bustos P.,ADL Diagnostic Chile Ltd
Bulletin of the European Association of Fish Pathologists | Year: 2012

The recent report of amoebic gill disease (AGD) and of Neoparamoeba perurans in Chile has made it necessary to develop practical tools that will be useful for carrying out epidemiological studies. AGD diagnosis was confirmed with a PCR specific to N. perurans. The prevalence of AGD in Atlantic salmon was 55.7% (29/52 farms) and the epidemic curve was observed between May 2007 and June 2008 closely related with low rainfall and high salinity (≥ 32%o). Fish weighing more than 300 g reared in Los Lagos Region during summer and autumn season showed 3.7 (p=0.0004), 4.2 (p=0.0178) and 6.2 (p=0.0031) times greater risk to be AGD positive, respectively. The reduction of Atlantic salmon biomass reared in Chile closely related with ISA crisis could considerably have increased the infection pressure of N. perurans to rainbow trout (63.2%, 12/19 farms) and coho salmon (90.9%, 10/11 farms). Source

Rozas M.,Austral University of Chile | Bohle H.,ADL Diagnostic Chile Ltd | Sandoval A.,ADL Diagnostic Chile Ltd | Ildefonso R.,ADL Diagnostic Chile Ltd | And 2 more authors.
Journal of Parasitology | Year: 2012

Between April and June 2009, 1,075 feral rainbow trout from 10 different lakes involved with aquaculture activities in Los Lagos Region, Chile, were inspected for Diphyllobothrium species. All viscera and muscles of the fish were examined using stereomicroscopy; pyloric cecae and stomachs infected with plerocercoids were checked by histology and scanning electron microscopy. Plerocercoids of Diphyllobothrium dendriticum were confirmed by PCR and sequencing of COI and 18S rRNA + ITS1 + 5.8S rRNA + ITS2 genes for the first time in Chile. Overall prevalence of plerocercoids of D. dendriticum was 9.2% (99/1,075) in Los Lagos Region and 17.4% (99/570) for Chiloe Island. Plerocercoids were not detected in the continental lakes of the Los Lagos Region (Chapo, Rupanco, and Llanquihue). Tarahuín Lake exhibited a prevalence of 50.9% (81/159), Cucao Lake 5.1% (4/79), Natri Lake 4.7% (5/107), Huillinco Lake 3.6% (5/138), and San Antonio Lake 66.7% (4/6). Abundance was 1.1 plerocercoid larvae per fish (1,169 larvae/1,075 fish). All the plerocercoids were found encysted in the viscera of the fish. Plerocercoids were 10.9 ± 3 (7-16) mm long by 0.4 ± 0.2 (0.2-0.6) mm wide. The scolex was enlarged, with 2 bothria and a frontal pit. The body was covered with short capilliform filitriches, 4-6 mm long. The Chilean COI and 18SrRNA + ITS1 + 5.8SrRNA + ITS2 gene sequences indicated 96.34-96.52% and 99% similarity with D. dendriticum sequences, respectively. Diphyllobothrium dendriticum is reported for the first time in freshwater ecosystems as far as 43°S on Chiloe Island. These findings and previous reports of plerocercoids of Diphyllobothrium spp. in farmed rainbow trout at Tarahuín Lake support the putative life cycle of this parasite in lakes of southern Chile where there are aquaculture activities. © American Society of Parasitologists 2012. Source

Rozas M.,ADL Diagnostic Chile Ltd | Bohle H.,ADL Diagnostic Chile Ltd | Ildefonso R.,ADL Diagnostic Chile Ltd | Bustos P.,ADL Diagnostic Chile Ltd
Bulletin of the European Association of Fish Pathologists | Year: 2011

The recent description of Amoebic Gill Disease (AGD) and Neoparamoeba perurans in Atlantic salmon (Salmo salar) farmed in Chile has necessitated the development of more reliable and sensitive diagnostic tests. Final diagnosis of infection is normally confirmed by histology. However, the correlation between gross gill lesions and histological lesions is generally unclear. In the current study, moderate concordance level (k=0.5319) between gross pathology and histology was observed. The sensitivity and specificity of gross pathology was 77.91% and 71.05%, respectively. Neoparamoeba spp. are considered morphologically indistinguishable therefore by using histopathology limits the capacity to characterise the causative agent and it can be time consuming. We developed a PCR assay to amplify the N. perurans 18S rRNA gene from gill clinical samples of AGD-affected fish. High concordance level (k=0.95) between PCR and histological examination was observed. The sensitivity and specificity of PCR assay was 94.64% and 97.06%, respectively. The PCR-based assay provides a rapid tool that will be useful to the diagnostic routine for AGD in Chile. Source

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