Browsing by Author "Arriagada, Gabriel"

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    Eliciting expert judgements to estimate risk and protective factors for Piscirickettsiosis in Chilean salmon farming
    (2019) Estévez Weinstein, Rodrigo Antonio; Mardones Loyola, Fernando Otoniel; Alamos, Felipe; Arriagada, Gabriel; Carey, Jan; Correa, Christian; Escobar-Dodero, Joaquín; Gaete, Alvaro; Gallardo, Alicia; Ibarra, Rolando; Ortiz, Cristhian; Rozas-Serri, Marco; Sandoval, Osvaldo; Santana, Jaime; Gelcich, Stefan
    Global production of farmed salmon is increasingly threatened by emerging infectious diseases. Piscirickettsiosis or Salmonid Rickettsial Septicemia (SRS), a disease caused by the bacterium Piscirickettsia salmonis, is the major responsible for the overall disease-specific mortalities in the Chilean salmon industry. In this study, we applied a structured expert elicitation process to identify risk and protective factors associated with severe outbreaks of SRS during a production cycle. We used a qualitative based-expert approach to calculate risk estimators for ten risk factors and seven protective factors. In the expert elicitation process, each participant independently estimated factors in two rounds. Between the first and second round, we facilitated a workshop among experts to discuss preliminary results. As a result, the inter-expert variation of the experts' estimates was systematically reduced. Our results are concordant with preliminary studies about risk factors for SRS. Importantly, we identified novel factors that may be associated to an increased risk for severe SRS outbreaks, such as fouling of cages, density of farms in neighborhoods, presence of sea lions and early mature salmonids. Novel factors that appear to reduce the risk of severe outbreaks of SRS were synchronized farm rest periods, opportune diagnosis and necropsy training. Using these results, we propose an intervention model to provide better information for strategic decision making.
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    Factors associated to the duration of COVID-19 lockdowns in Chile
    (2022) Pavani, Jessica; Cerda, Jaime; Gutierrez, Luis; Varas, Ines; Gutierrez, Ivan; Jofre, Leonardo; Ortiz, Oscar; Arriagada, Gabriel
    During the first year of the COVID-19 pandemic, several countries have implemented non-pharmacologic measures, mainly lockdowns and social distancing, to reduce the spread of the SARS-CoV-2 virus. These strategies varied widely across nations, and their efficacy is currently being studied. This study explores demographic, socioeconomic, and epidemiological factors associated with the duration of lockdowns applied in Chile between March 25th and December 25th, 2020. Joint models for longitudinal and time-to-event data were used. In this case, the number of days under lockdown for each Chilean commune and longitudinal information were modeled jointly. Our results indicate that overcrowding, number of active cases, and positivity index are significantly associated with the duration of lockdowns, being identified as risk factors for longer lockdown duration. In short, joint models for longitudinal and time-to-event data permit the identification of factors associated with the duration of lockdowns in Chile. Indeed, our findings suggest that demographic, socioeconomic, and epidemiological factors should be used to define both entering and exiting lockdown.