Browsing by Author "Zimin Veselkoff, Natalia"

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    50 years of cetacean strandings reveal a concerning rise in Chilean patagonia
    (2020) Alvarado-Rybak, Mario; Toro, Frederick; Escobar-Dodero, Joaquín; Kinsley, Amy C.; Sepúlveda, Maximiliano A.; Capella, Juan; Azat, Claudio; Cortés Hinojosa, Galaxia Andrea; Zimin Veselkoff, Natalia; Mardones, Fernando O.
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    Epidemiological Factors Associated With Caligus rogercresseyi Infection, Abundance, and Spatial Distribution in Southern Chile
    (FRONTIERS MEDIA SA, 2021) Lepe Lopez, Manuel; Escobar Dodero, Joaquin; Rubio, Daniel; Alvarez, Julio; Zimin Veselkoff, Natalia; Mardones, Fernando O.
    Sea lice (Caligus rogercresseyi) are external parasites that affect farmed salmonids in Chile, and the scale of their sanitary and economic impact cannot be overstated. Even though space-time patterns suppose parasite aggregation, specific locations related to different infestation levels, as well as their associated factors across the geographic range involved, had not been investigated as of the writing of the present article. The understanding of the effects and factors entailed by the presence of C. rogercresseyi may be deemed a key element of Integrated Pest Management (IPM). In the present study, the multivariate spatial scan statistic was used to identify geographic areas and times of C. rogercresseyi infestation and to estimate the factors associated with such patterns. We used official C. rogercresseyi monitoring data at the farm level, with a set of 13 covariates, to provide adjustment within the analyses. The analyses were carried out for a period of 5 years (2012-2016), and they included three fish species (Salmo salar, Oncorhynchus mykiss, and Oncorhynchus kisutch) in order to assess the consistency of the identified clusters. A retrospective multinomial, spatial, and temporal scan test was implemented to identify farm clusters of either of the different categories of C. rogercresseyi infested farms: baseline, medium, and high, based on the control chemical threshold established by the health authority. The baseline represents adequate farm performance against C. rogercresseyi infestation. Then, production and environmental factors of the medium and high infestation farms were compared with the baseline using regression techniques. The results revealed a total of 26 clusters (p < 0.001), of which 12 correspond to baseline, 1 to medium, and the remaining 13 to high infestation clusters. In general, baseline clusters are detected in a latitudinal gradient on estuarine areas, with increasing relative risks to complex island water systems. There is a spatial structure in specific sites, north of Los Lagos Region and central Aysen Region, with high infestation clusters and epidemic peaks during 2013. In addition, average weight, salmon species, chemotherapeutants, latitude, temperature, salinity, and year category are factors associated with these C. rogercresseyi patterns. Recommendations for an IPM plan are provided, along with a discussion that considers the involvement of stock density thresholds by salmon species and the spatial structure of the efficacy of chemical control, both intended to avoid the advance of resistance and to minimize environmental residues.
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    Expert elicitation of the diagnostic performance of two tests for Bacterial Kidney Disease (BKD) surveillance in Atlantic salmon (Salmo salar L.) broodstock in Chile
    (2020) Verdugo, C.; Zimin Veselkoff, Natalia; Gardner, I.A.; Mardones, F.O.
    The objective of this study was to obtain diagnostic performance estimates for immunofluorescence antibody test (IFAT) and quantitative polymerase chain reaction (qPCR) tests, for Bacterial Kidney Disease (BKD) surveillance in farmed Atlantic salmon (Salmo salar.) broodstock without clinical signs compatible with the disease in Chile. To obtain diagnostic sensitivity (DSe) and specificity (DSp) estimates of those tests, an expert elicitation process was conducted using the trial roulette method during a workshop with 18 national experts on BKD diagnostics and control. A questionnaire was given to the experts to gather information on their previous experience with BKD, and 12 experts who received an introduction to the expert-elicitation process and graphical representation of statistical distributions. Experts were divided into three groups and requested to draw distributions of DSe and DSp parameters using an online tool. Then figures where projected and discussed among participants. After the discussion round, experts were requested to redraw their distributions (if considered necessary). The agreement between groups was assessed by calculating the overlapping areas between the three distributions for each parameter. Finally, a consensus distribution was generated. In general, groups had moderate to high agreement with overlapping areas between 53% to 93% for DSpIFAT, DSeqPCR, and DSpqPCR. Conversely, no agreement was reached for the DSeIFAT distribution. Specifically, median estimates of 89.5%, 90.5%, and 95.9%, were obtained for DSpIFAT, DSeqPCR, & DSpqPCR, respectively. In the case of DSeIFAT, the first group provided a median estimate of 28%, whereas groups 2 and 3 reached a consensus value of approximately 62%. This study provides information that is not available in the country, and will help to adjust current BKD control programs, which mainly rely on the use of qPCR assays.
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    The COVID-19 Pandemic and Global Food Security
    (2020) Mardones, Fernando O.; Rich, K. M.; Boden, L. A.; Moreno Switt, Andrea Isabel; Caipo, M. L.; Zimin Veselkoff, Natalia; Alateeqi, A. M.; Baltenweck, I.