Browsing by Author "Undurraga Fourcade, Eduardo Andrés"

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    A dynamic modeling tool for estimating healthcare demand from the COVID19 epidemic and evaluating population-wide interventions
    (2020) Rainisch, Gabriel; Undurraga Fourcade, Eduardo Andrés; Chowell, Gerardo
    Objectives: Public health officials need tools to assist in anticipating the healthcare resources required to confront the SARS-COV-2 pandemic. We constructed a modeling tool to aid active public health officials to estimate healthcare demand from the pandemic in their jurisdictions and to evaluate the potential impact of population-wide social-distancing interventions. Methods: The tool uses an SEIR compartmental model to project the pandemic’s local spread. Users input case counts, healthcare resources, and select intervention strategies to evaluate. Outputs include the number of infections and deaths with and without intervention, and the demand for hospital and critical care beds and ventilators relative to existing capacity. We illustrate the tool using data from three regions of Chile. Results: Our scenarios indicate a surge in COVID-19 patients could overwhelm Chilean hospitals by June, peaking in July or August at six to 50 times the current supply of beds and ventilators. A lockdown strategy or combination of case isolation, home quarantine, social distancing of individuals >70 years, and telework interventions may keep treatment demand below capacity. Conclusions: Aggressive interventions can avert substantial morbidity and mortality from COVID-19. Our tool permits rapid evaluation of locally-applicable policy scenarios and updating of results as new data become available.
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    Análisis epidemiológico de la leptospirosis humana en Colombia, 2015-2020
    (2023) Parra Barrera, Eliana Liseth; Torres Hidalgo, Marisa; Undurraga Fourcade, Eduardo Andrés; Pontificia Universidad Católica de Chile. Escuela de Medicina
    Antecedentes: Colombia es un país endémico de la leptospirosis. La notificación de los casos sospechosos es obligatoria y se realiza al Sistema Nacional de Vigilancia. La confirmación diagnóstica de los casos se realiza en el Laboratorio Nacional de Referencia. El presente estudio planteó el desarrollo de dos objetivos generales, como sigue: Objetivo 1: Determinar la distribución de los casos de leptospirosis humana con confirmación diagnóstica por el Laboratorio Nacional de Referencia en Colombia entre los años 2015 a 2020. Objetivo 2: Analizar los factores clínicos y epidemiológicos de los casos de leptospirosis humana confirmados respecto a su asociación con la forma grave o letal de la enfermedad. Metodología: Para el desarrollo del primer objetivo general se planteó un diseño descriptivo retrospectivo de los casos confirmados al Laboratorio Nacional de Referencia. En el desarrollo del segundo objetivo general, se realizó un análisis de regresión de casos de leptospirosis con confirmación diagnóstica y reporte clínico para la identificación de los factores de riesgo asociados con el desenlace de leptospirosis grave y mortalidad. Resultados: En los seis años analizados se notificaron al laboratorio Nacional de Referencia 3.535 casos, 880 (24,9%). La incidencia general de casos confirmados fue de 1,9 por 100.000 habitantes, afectando más a hombres (82,1%) que a mujeres (17,8%). Un total de 54 (6,1%) muertes fueron confirmadas como leptospirosis. Los serovares más frecuentes fueron Australis (21,1%), Autumnalis (6,9%), Wolfii (6,3%), Ballum (5,8%), Tarasovi (5,7%), Bratislava (5,5%) y Hebdomadis (4,4%). El serovar Bratislava se asoció significativamente en los casos con mortalidad (p = 0,007). Los casos de leptospirosis grave fueron clasificados según las manifestaciones clínicas como falla renal (29,9%), hepática (27,4%) y multiorgánica (24,4%), shock séptico (24,4%), síndrome de Weil (18,4%), hemorragia pulmonar (18,4%) y meningitis (2,5%). Observándose casos que requirieron el ingreso a UCI (30,3%) y que fueron fatales (8,5%). Las variables asociadas a la leptospirosis grave fueron dificultad respiratoria (OR: 4,57 IC: 1,17-17,80, p<0,028), lesión renal (OR: 15,7 IC:2,40-103,29, p=0,004), taquicardia (OR: 5,93 IC:1,04-33,53, p<0,044) y erupción cutánea (OR:8,14 IC:2,61-25,42, p<0,001). El desenlace de admisión en la UCI se asoció a trombocitopenia (OR: 6,81 IC:1,89-24,4, p<0,003), dificultad respiratoria (OR:10,48 IC:3,12-35,13, <0,001), lesión renal (OR: 32,2 IC: 4,5-119,01, <0,001), taquicardia (OR: 4,29 IC:11,15-15,95, p=0,030) y erupción cutánea (OR: 7,78 IC:2,09 -29,00, p=0,002). La mortalidad fue asociada la edad avanzada (>60 años) (OR: 6,12 IC:1,40-26,76, p=0,016), ictericia (OR: 11,96 IC: 1,35-108,82, p=0,028) y meningitis (OR: 14,30 IC: 1,15-177,64, p=0,038). Conclusión: El estudio evidenció la persistencia de la transmisión de la leptospirosis en hombres, con casos en todos los grupos de edad analizados. Los datos presentaron una distribución heterogénea entre las regiones del país. La dificultad respiratoria y la erupción cutánea se asociaron tanto a la enfermedad grave como a la admisión a la UCI, y la ictericia se asoció con la mortalidad.
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    Andes network-studying early psychosis in Latin America
    (2019) Crossley, Nicolás; Guinjoan, S.; Rivera, G.; Jackowski, A.; Gadelha, A.; Elkis, H.; Louza, M.; Gama, C.; Evans-Lacko, S.; Castaneda, C.P.; Undurraga Fourcade, Eduardo Andrés; Cordoba, R.; Bressan, R.
    Background Our knowledge about schizophrenia is largely based on studies in developed countries such as the United States, Western Europe or Japan. Their findings have pointed to several risk factors or modulators of response which unfortunately are more prevalent and stronger in low and middle-income countries. These include exposure to violence and trauma, poor perinatal care, or limited (and potentially late) access to healthcare. In this context, there is a pressing need to raise information from these countries about psychosis. We here present to the SIRS community the Latin American Consortium ANDES whose main aim is to study early psychosis within the Latin American context. Methods This is a descriptive study characterizing the groups and the cohorts of patients included that are part of the ANDES network. Results 15 different groups from 6 different countries from Latin America are part of the network, including Argentina, Bolivia, Brazil, Chile, Colombia and Mexico. The network includes several early intervention clinical services, such as those in São Paulo and Santiago, who receive jointly around 5 new cases of first episode a week. ANDES also integrates three groups studying ultra-high-risk subjects (2 in São Paulo, 1 in Mexico). All groups have already acquired data from studies on first episode patients whose characteristics will be presented. Available data includes clinical and sociodemographic information from more than 1,000 patients, cognitive assessments using MATRICS from more than 500 patients, and 600 MRI T1 scans, DTI and resting-state fMRI (350 patients and 250 controls). Discussion ANDES is a unique opportunity to study psychosis in deprived settings which are frequently less represented in research publications. The inequality present in Latin America provides opportunities to study the effect of exposures to an adverse environment within this population.
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    Benchmarking the Covid-19 pandemic across countries and states in the USA under heterogeneous testing
    (2020) Asahi Kodama, Kenzo Javier; Undurraga Fourcade, Eduardo Andrés; Wagner, Rodrigo; CEDEUS (Chile)
    Public health officials need to make urgent decisions to reduce the potential impact of the CoVID-19 pandemic. Benchmarking based on the increase in total cases or case fatality rates is one way of comparing performance across countries or territories (such as states in the USA), and could inform policy decisions about COVID-19 mitigation strategies. But comparing cases and fatality across territories is challenging due to heterogeneity in testing and health systems. We show two complementary ways of benchmarking across countries or US states. First, we used multivariate regressions to estimate the test-elasticity-of-COVID-19-case-incidence. We found a 10% increase in testing yielded ~9% (95% CI:4.2–3.4%; p<0.001) increase in reported cases across countries, and ~2% (95%CI:0.1-3.4%; p=0.03) increase across US states during the week ending April 10th, 2020. We found comparable negative elasticities for fatality rates (across countries: β =-0.77, 95%CI:-1.40– -0.14; p=0.02; US states: β=-0.15, 95%CI:-0.30-0.01; p=0.06). Our results were robust to various model specifications. Second, we decomposed the growth in cases into test growth and positive test ratio (PTR) growth to intuitively visualize the components of case growth. We hope these results can help support evidence-based decisions by public health officials as more consistent data hopefully becomes available.
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    Birth seasons and heights among girls and boys below 12 years of age: lasting effects and catch-up growth among native Amazonians in Bolivia
    (2018) Brabec, Marek; Behrman, Jere R.; Emmett, Susan D.; Gibson, Edward; Kidd, Celeste; Leonard, William; Penny, Mary E.; Piantadosi, Steven T.; Sharma, Abhishek; Tanner, Susan; Undurraga Fourcade, Eduardo Andrés; Godoy, Ricardo A.
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    Catch-up growth and growth deficits : Nine-year annual panel child growth for native Amazonians in Bolivia
    (2016) Leonard, W.; Behrman, J.; Godoy, R.; Zhang, R.; Undurraga Fourcade, Eduardo Andrés; Zeng, W.; Reyes García, V.; Tanner, S.
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    Centre-based care is a significant predictor of lower body mass index in early childhood: Longitudinal evidence from Chile
    (2020) Allel, Kasim; Narea Biscupovich, Marigen Soledad; Undurraga Fourcade, Eduardo Andrés
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    Challenges and Potential of Remote Sensing for Assessing Salmonella Risk in Water Sources: Evidence from Chile
    (MDPI, 2025) Palharini, Rayana Santos Araujo; González Reyes, Makarena Sofía; Ferreira Monteiro, Felipe; Mendoza Villavicencio, Lourdes Milagros; Adell, Aiko D.; Toro, Magaly; Moreno Switt, Andrea Isabel; Undurraga Fourcade, Eduardo Andrés
    Waterborne illnesses, including those caused by Salmonella, are an increasing public health challenge, particularly in developing countries. Potential sources of salmonellosis include fruits and vegetables irrigated/treated with surface water, leading to human infections. Salmonella causes millions of gastroenteritis cases annually, but early detection through routine water quality surveillance is time-consuming, requires specialized equipment, and faces limitations, such as coverage gaps, delayed data, and poor accessibility. Climate change-driven extreme events such as floods and droughts further exacerbate variability in water quality. In this context, remote sensing offers an efficient and cost-effective alternative for environmental monitoring. This study evaluated the potential of Sentinel-2 satellite imagery to predict Salmonella occurrence in the Maipo and Mapocho river basins (Chile) by integrating spectral, microbiological, climatic, and land use variables. A total of 1851 water samples collected between 2019 and 2023, including 704 positive samples for Salmonella, were used to develop a predictive model. Predicting Salmonella in surface waters using remote sensing is challenging for several reasons. Satellite sensors capture environmental proxies (e.g., vegetation cover, surface moisture, and turbidity) but not pathogens. Our goal was to identify proxies that reliably correlate with Salmonella. Twelve spectral indices (e.g., NDVI, NDWI, and MNDWI) were used as predictors to develop a predictive model for the presence of the pathogen, which achieved 59.2% accuracy. By spatially interpolating the occurrences, it was possible to identify areas with the greatest potential for Salmonella presence. NDWI and AWEI were most strongly correlated with Salmonella presence in high-humidity areas, and spatial interpolation identified the higher-risk zones. These findings reveal the challenges of using remote sensing to identify environmental conditions conducive to the presence of pathogens in surface waters. This study highlights the methodological challenges that must be addressed to make satellite-based surveillance an accessible and effective public health tool. By integrating satellite data with environmental and microbiological analyses, this approach can potentially strengthen low-cost, proactive environmental monitoring for public health decision-making in the context of climate change.
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    Child stunting is associated with weaker human capital among native Amazonians
    (2018) Undurraga Fourcade, Eduardo Andrés; Behrman, Jere R.; Emmett, Susan D.; Kidd, Celeste; Leonard, William R.; Piantadosi, Steven T.; Reyes-Garcia, Victoria; Sharma, Abhishek; Zhang, Rebecca; Godoy, Ricardo A.
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    Clinical, laboratory, and demographic determinants of hospitalization due to dengue in 7613 patients : a retrospective study based on hierarchical models
    (2018) Santos da Silva, Natal; Undurraga Fourcade, Eduardo Andrés; da Silva Ferreira, Elis Regina; Estofolete, Cássia Fernanda; Lacerda Nogueira, Maurício
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    Commonality and variation in mental representations of music revealed by a cross-cultural comparison of rhythm priors in 15 countries
    (2021) Jacoby, Nori; Polak, Rainer; Grahn, Jessica Adrienne; Cameron, Daniel J.; Lee, Kyung Myun; Godoy, Ricardo; Undurraga Fourcade, Eduardo Andrés; Huanca, Tomas; Thalwitzer, Timon; Doumbia, Noumouké; Goldberg, Daniel; Margulis, Elizabeth; Wong, Patrick; Jure, Luis; Rocamora, Martín; Fujii, Shinya; Savage, Patrick E.; Ajimi, Jun; Konno, Rei; Oishi, Sho; Jakubowski, Kelly; Holzapfel, André; Mungan, Esra; Kaya, Ece; Rao, Preeti; Ananthanarayana, Rohit Mattur; Alladi, Suvarna; Tarr, Bronwyn; Anglada-Tort, Manuel; Harrison, Peter M. C.; McPherson, Malinda J.; Dolan, Sophie; Durango, Alex; Mcdermott, Josh
    Music is present in every known society, yet varies from place to place. What, if anything, is universal to music cognition? We measured a signature of mental representations of rhythm in 39 participant groups in 15 countries, spanning urban societies and indigenous populations. Listeners reproduced random ‘‘seed’’ rhythms; their reproductions were fed back as the stimulus (as in the game of “telephone”), such that their biases (the prior) could be estimated from the distribution of reproductions. Every tested group showed a sparse prior with peaks at integer ratio rhythms. However, the importance of different integer ratios varied across groups, often reflecting local musical practices. Our results suggest a common feature of music cognition – discrete rhythm “categories” at small integer ratios. These discrete representations likely stabilize musical systems in the face of cultural transmission, but interact with culture-specific traditions to yield diversity evident when mental representations are probed across many cultures.
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    Comparison between the traditional (1997) and revised (2009) WHO classifications of dengue disease: a retrospective study of 30 670 patients
    (2018) Santos da Silva, Natal; Undurraga Fourcade, Eduardo Andrés; Tobal Verro, Alice; Lacerda Nogueira, Maurício
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    Conditional cash transfers for primary education: Which children are left out?
    (2018) Bauchet, Jonathan; Undurraga Fourcade, Eduardo Andrés; Reyes-Garcia, Victoria; Behrman, Jere R.; Godoy, Ricardo A.
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    Cost-effectiveness Analysis of Integrated Bite Case Management and Sustained Dog Vaccination for Rabies Control
    (2023) Taylor, Ema; Prada, Joaquin M.; Del Rio Vilas, Victor; Undurraga Fourcade, Eduardo Andrés; Wallace, Ryan; Horton, Daniel L.
    The successful prevention, control, and elimination of dog-mediated rabies is challenging due to insuffi cient resource availability and inadequate placement. An integrated dog bite case management (IBCM) system plus dog vaccination can help address these challenges. Based on data from the IBCM system in Haiti, we conducted a cost effectiveness evaluation of a newly established IBCM system plus sustained vaccination and compared it with 1) a no bite-case management (NBCM) and 2) a non–risk-based (NRB) program, where bite victims presenting at a health clinic would receive post-exposure prophylaxis regardless of risk assessment. We also provide cost-effectiveness guidance for an ongoing IBCM system and for sub-optimal dog vaccination coverages, considering that not all cost-effective inter ventions are affordable. Cost-effectiveness outcomes included average cost per human death averted (USD/death averted) and per life-year gained (LYG). The analysis used a governmental perspective. Considering a sustained 5-year implementation with 70% dog vaccination coverage, IBCM had a lower average cost per death averted (IBCM: $7,528, NBCM: $7,797, NRB: $15,244) and cost per LYG (IBCM: $152, NBCM: $158, NRB: $308) than NBCM and NRB pro grams. As sensitivity analysis, we estimated cost-effectiveness for alternative scenarios with lower dog-vaccination coverages (30%, 55%) and lower implementation costs. Our results suggest that better health and cost-effectiveness outcomes are achieved with the continued implementation of an IBCM program ($118 per life-year saved) compared with a newly established IBCM program ($152 per life-year saved). Our results suggest that IBCM is more cost-effective than non-integrated programs to eliminate dog-mediated human rabies.
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    Cost-effectiveness of community mobilization (Camino Verde) for dengue prevention in Nicaragua and Mexico : A cluster randomized controlled trial
    (2020) Tschampl, C. A.; Undurraga Fourcade, Eduardo Andrés; Ledogar, R. J.; Coloma, J.; Legorreta Soberanis, J.; Paredes Solis, S.; Arostegui, J.; Hernandez Alvarez, C.; Harris, E.; Andersson, N.; Shepard, D. S.
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    Cost-effectiveness of dog rabies vaccination programs in East Africa
    (2018) Borse, Rebekah H.; Atkins, Charisma Y.; Gambhir, Manoj; Undurraga Fourcade, Eduardo Andrés; Blanton, Jesse D.; Kahn, Emily B.; Dyer, Jessie L.; Rupprecht, Charles E.; Meltzer, Martin I.
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    COVID-19 case fatality risk by age and gender in a high testing setting in Latin America: Chile, March–August 2020
    (2021) Undurraga Fourcade, Eduardo Andrés; Chowell, Gerardo; Mizumoto, Kenji
    Abstract Background Early severity estimates of coronavirus disease 2019 (COVID-19) are critically needed to assess the potential impact of the ongoing pandemic in different demographic groups. Here we estimate the real-time delay-adjusted case fatality rate across nine age groups by gender in Chile, the country with the highest testing rate for COVID-19 in Latin America. Methods We used a publicly available real-time daily series of age-stratified COVID-19 cases and deaths reported by the Ministry of Health in Chile from the beginning of the epidemic in March through August 31, 2020. We used a robust likelihood function and a delay distribution to estimate real-time delay-adjusted case-fatality risk and estimate model parameters using a Monte Carlo Markov Chain in a Bayesian framework. Results As of August 31, 2020, our estimates of the time-delay adjusted case fatality rate (CFR) for men and women are 4.16% [95% Credible Interval (CrI): 4.09–4.24%] and 3.26% (95% CrI: 3.19–3.34%), respectively, while the overall estimate is 3.72% (95% CrI: 3.67–3.78%). Seniors aged 80 years and over have an adjusted CFR of 56.82% (95% CrI: 55.25–58.34%) for men and 41.10% (95% CrI: 40.02–42.26%) for women. Results showed a peak in estimated CFR during the June peak of the epidemic. The peak possibly reflects insufficient laboratory capacity, as illustrated by high test positivity rates (33% positive 7-day average nationally in June), which may have resulted in lower reporting rates. Conclusions Severity estimates from COVID-19 in Chile suggest that male seniors, especially among those aged ≥ 70 years, are being disproportionately affected by the pandemic, a finding consistent with other regions. The ongoing pandemic is imposing a high death toll in South America, and Chile has one of the highest reported mortality rates globally thus far. These real-time estimates may help inform public health officials' decisions in the region and underscore the need to implement more effective measures to ameliorate fatality.
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    COVID-19 Has Exposed How 'The Other Half' (Still) Lives
    (2020) Gil Ureta, Magdalena; Undurraga Fourcade, Eduardo Andrés
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    Effectiveness and duration of a second COVID-19 vaccine booster
    (2022) Jara, Alejandro; Cuadrado, Cristobal; Undurraga Fourcade, Eduardo Andrés; García, Christian; Najera, Manuel; Bertoglia, María Paz; Vergara, Verónica; Fernández, Jorge; García, Heriberto; Araos, Rafael
    Using a prospective national cohort of 3.75 million individuals aged 20 or older, we evaluated the effectiveness against COVID-19 related ICU admissions and death of mRNA-based second vaccine boosters for four different three-dose background regimes: BNT162b2 primary series plus a homologous booster, and CoronaVac primary series plus an mRNA booster, a homologous booster, and a ChAdOx-1 booster. We estimated the vaccine effectiveness weekly from February 14 to August 15, 2022, by estimating hazard ratios of immunization over non-vaccination, accounting for relevant confounders. The overall adjusted effectiveness of a second mRNA booster shot was 88.2% (95%CI, 86.2-89.9) and 90.5% (95%CI 89.4-91.4) against ICU admissions and death, respectively. Vaccine effectiveness showed a mild decrease for all regimens and outcomes, probably associated with the introduction of BA.4 and BA.5 Omicron sub-lineages and immunity waning. The duration of effectiveness suggests that no additional boosters are needed six months following a second booster shot.