Direct impact of COVID-19 vaccination in Chile: averted cases, hospitalizations, ICU admissions, and deaths.

BACKGROUND: Chile rapidly implemented an extensive COVID-19 vaccination campaign, deploying a diversity of vaccines with a strategy that prioritized the elderly and individuals with comorbidities. This study aims to assess the direct impact of vaccination on the number of COVID-19 related cases, hospital admissions, ICU admissions and deaths averted during the first year and a half of the campaign. METHODS: Via Chile's transparency law, we obtained access to weekly event counts categorized by vaccination status and age. Integrating this data with publicly available census and vaccination coverage information, we conducted a comparative analysis of weekly incidence rates between vaccinated and unvaccinated groups from December 20, 2020 to July 2, 2022 to estimate the direct impact of vaccination in terms of the number of cases, hospitalizations, ICU admissions and deaths averted, using an approach that avoids the need to explicitly specify the effectiveness of each vaccine deployed. RESULTS: We estimated that, from December 20, 2020 to July 2, 2022 the vaccination campaign directly prevented 1,030,648 (95% Confidence Interval: 1,016,975-1,044,321) cases, 268,784 (95% CI: 264,524-273,045) hospitalizations, 85,830 (95% CI: 83,466-88,194) ICU admissions and 75,968 (95% CI: 73,909-78,028) deaths related to COVID-19 among individuals aged 16 years and older. This corresponds to a reduction of 26% of cases, 66% of hospital admissions, 70% of ICU admissions and 67% of deaths compared to a scenario without vaccination. Individuals 55 years old or older represented 67% of hospitalizations, 73% of ICU admissions and 89% of deaths related to COVID-19 prevented. CONCLUSIONS: This study highlights the role of Chile's vaccination campaign in reducing COVID-19 disease burden, with the most substantial reductions observed in severe outcomes.

[Epidemiology of cysticercosis in Chile]. / Riesgo y distribución geográfica de neurocisticercosis en Chile según egresos hospitalarios (2002-2019).

BACKGROUND: Neurocysticercosis is the most prevalent parasitic disease of the central nervous system in Chile, where sporadic cases are reported, without information about the epidemiology or distribution of the disease. AIM: To identify the main risk zones for cysticercosis in Chile. MATERIAL AND METHODS: Analysis of hospital discharge databases between 2002 and 2019, available at the website of the Chilean Ministry of Health. Cases with B69 code of the tenth international classification of diseases were identified. RESULTS: In the study period, there were 1752 discharges with the diagnoses of neurocysticercosis, ocular cysticercosis and cysticercosis of other sites. The ages of patients ranged from 0 to 89 years with a clustering between 30 and 59 years. Sixty two percent were males. The zone between the regions of Maule and Araucania concentrated 82% of cases. CONCLUSIONS: We identified the zone with the greatest concentration of cysticercosis in Chile, where preventive strategies should eventually be directed.

Epidemic trends, public health response and health system capacity: the Chilean experience in four months of the COVID-19 pandemic.

OBJECTIVES: To report the surveillance of COVID-19 pandemic in Chile and analyse the response to public health interventions implemented from 3 March to 30 June 2020 and to assess the risks of collapse of the health care system. METHODS: We analysed the effective reproductive number, underreporting of cases, burden of critical beds, case fatality ratio and number of diagnostic RT-PCR for SARS-CoV-2. RESULTS: After an accelerated onset, the COVID-19 pandemic seemed to be relatively controlled in Chile (late April 2020), with reproductive numbers close to 1.00. However, at this time, the load of infected patients was high, with an important number of underreported cases; the diagnostic effort was still limited and heterogeneous across regions. After 1 May up to 30 June a marked exponential increase in the number of cases was observed with a peak on June 14. In this last period the occupation of intensive care unit beds increased to saturation level (89% nationally; 95% in the Metropolitan Region). CONCLUSIONS: Our findings suggest that the implemented public health interventions have been initially effective in decreasing the spread of the pandemic. Premature decisions to relax these interventions may have resulted in a rebound in cases with a rapid saturation of the health care system.

OBJETIVOS: Informar sobre la vigilancia de la pandemia por COVID-19 en Chile, analizar la respuesta a las intervenciones de salud pública implementadas desde el 3 de marzo hasta el 30 de junio de 2020 y evaluar los riesgos de colapso del sistema de salud. MÉTODOS: Se analizó el número reproductivo efectivo, el subregistro de casos, la carga sobre las camas de cuidados intensivos disponibles, la tasa de letalidad y el número de pruebas diagnósticas de RT-PCR efectuadas para el SARS-CoV-2. RESULTADOS: Tras un inicio acelerado, la pandemia por COVID-19 parecía estar relativamente controlada en Chile a finales de abril de 2020, con números reproductivos cercanos a 1,00. Sin embargo, en ese momento, la carga de pacientes infectados activos era elevada, con un número importante de casos no notificados; la capacidad diagnóstica era todavía limitada y heterogénea entre las regiones del país. Desde el 1 de mayo hasta el 30 de junio se observó un marcado incremento exponencial en el número de casos, con un pico el 14 de junio. En este último período la ocupación de camas en las unidades de cuidados intensivos aumentó hasta el nivel de saturación (89% a nivel nacional; 95% en la Región Metropolitana). CONCLUSIONES: Nuestros hallazgos sugieren que las intervenciones de salud pública implementadas parecen haber sido efectivas inicialmente para disminuir la propagación de la pandemia. Las decisiones prematuras de relajar estas intervenciones pueden haber ocasionado un rebote en los casos con una rápida saturación del sistema de atención de salud.

Daily thermal preference variation of the sand recluse spider Sicarius thomisoides (Araneae: Sicariidae).

Preferential temperature as a physiological feature is crucial for spiders, since it determines the selection of key habitats for their survival and reproduction. In this work, we study the daily and geographical variation of the preferential temperature of the spider Sicarius thomisoides subjected to different degrees of daily thermal oscillation in their habitats. Preferred temperatures differ between coastal and inland populations, but in both cases, there is a marked bimodality in the daily pattern of temperature preference, with two peaks per day that would be given by the changes in the hours of activity. These nocturnal spiders select higher temperatures in the evening (active period) and select lower temperatures during late morning (resting period). In laboratory, spiders have preferred temperatures that differ from those found in their habitats, so they must tolerate or compensate non-preferred temperatures by active thermoregulation in natural conditions.

[Calculating the risk of acquiring measles of chileans traveling abroad]. / Riesgo de contagio de sarampion para un viajero chileno en 2017.

BACKGROUND: There is always a risk of importing infectious diseases when travelling abroad. AIM: To estimate the effective risk of a Chilean of acquiring measles during a travel by countries where measles outbreaks have been reported, considering the present level of immunity in the country. MATERIAL AND METHODS: Previously established mathematical models using differential equations were applied to calculate the risk of acquiring measles of people traveling to endemic areas. RESULTS: The probability of acquiring measles of a voyager is 8.11 x 10-8. CONCLUSIONS: These estimations help decision making about preventive measures for travelers to endemic measles areas.

[Effects of climate change on reproductive number of Chagas disease]. / Estimando el efecto del cambio climático sobre el riesgo de la enfermedad de Chagas en Chile por medio del número reproductivo.

BACKGROUND: Reproductive number (R0)-maps estimate risk zones of vector-borne diseases and geographical distribution changes under climate change. AIM: To map R0 aiming to estimate the epidemiological risk of Chagas disease in Chile, its distribution and possible changes due to the global climate change. MATERIAL AND METHODS: We used a relationship between R0 and entomological parameters of vectors as function of environmental variables, to map the risk of Chagas disease in Chile, under current and projected future environmental conditions. RESULTS: We obtained a geographical R0 estimation of Chagas disease in Chile. The highest R0averages correspond to the Central-Northern regions of Chile. T. cruzi transmission area could increase in the future due to climate changes. Independent of the future condition, both for optimistic and pessimistic climate change scenarios, the area of potential risk for Chagas disease transmission would increase. The estimated R0 values suggest that, if a control of T. infestans is not maintained, Chagas disease endemic status will persist or increase, independently of the climate change scenarios. CONCLUSIONS: Mapping R0 values is an effective method to assess the risk of Chagas disease. The eventual increase in the transmission area of the disease is worrisome.

Assessing the risk zones of Chagas' disease in Chile, in a world marked by global climatic change.

BACKGROUND: Vector transmission of Trypanosoma cruzi appears to be interrupted in Chile; however, data show increasing incidence of Chagas' disease, raising concerns that there may be a reemerging problem. OBJECTIVE: To estimate the actual risk in a changing world it is necessary to consider the historical vector distribution and correlate this distribution with the presence of cases and climate change. METHODS: Potential distribution models of Triatoma infestans and Chagas disease were performed using Maxent, a machine-learning method. FINDINGS: Climate change appears to play a major role in the reemergence of Chagas' disease and T. infestans in Chile. The distribution of both T. infestans and Chagas' disease correlated with maximum temperature, and the precipitation during the driest month. The overlap of Chagas' disease and T. infestans distribution areas was high. The distribution of T. infestans, under two global change scenarios, showed a minimal reduction tendency in suitable areas. MAIN CONCLUSION: The impact of temperature and precipitation on the distribution of T. infestans, as shown by the models, indicates the need for aggressive control efforts; the current control measures, including T. infestans control campaigns, should be maintained with the same intensity as they have at present, avoiding sylvatic foci, intrusions, and recolonisation of human dwellings.

Interactions Between the Chilean Recluse Spider (Araneae: Sicariidae) and an Araneophagic Spitting Spider (Araneae: Scytodidae).

In Chile, all necrotic arachnidism is attributed to the Chilean recluse spider, Loxosceles laeta Nicolet, a species that shares the microenvironmental habitats with the spitting spider Scytodes globula Nicolet. The latter species has been proposed as a potential predator of L. laeta. For this research, we studied the interaction between both species during individual encounters to assess the possibility of population regulation of L. laeta cohorts exposed to this potential predator. We found that in most encounters S. globula prevailed. Also, S. globula preys on spiderlings of L. laeta, with a population effect on cohorts of this species. These findings suggest that S. globula may be influencing L. laeta populations in central Chile. The population regulation of L. laeta by predation would be important because this species, in the absence of predators, has a high reproductive rate, and it can maintain populations of large size. However according to our results, although S. globula may aid in the reduction of both spiderling and adult L. laeta populations, and perhaps other Loxosceles species, it is insufficient for biological control of Loxosceles species. Its presence together with other control measures such as hygiene of the rooms can help to decrease loxoscelism incidence.

The effects of temperature on the gas exchange cycle in Agathemera crassa.

Insects exhibit three patterns of gas exchange: continuous (CoGE), cyclic (CGE) and discontinuous (DGE). In this work, we present the first record of a DGE in Phasmatodea and its transition to CGE and to CoGE through a thermal gradient. The rate of CO2 production (VCO2) at 10, 20 and 30°C was examined in adults of Agathemera crassa, a high-Andean phasmid of central Chile. Carbon dioxide release was recorded during 24 h with L:D cycle of 12:12 h in order to record both rest and activity periods. At rest, A. crassa showed three patterns of gas exchange, highlighting the use of DGE preferably at 10°C. As the temperature increased, the CoGE pattern was more frequent being the only pattern observed in all individuals at 30°C. During activity, patterns changed to CoGE with a significant increase in VCO2. Our results support the idea that gas exchange patterns in insects are not distinct but correspond to a continuum of responses addressed by metabolic demand and where DGE can be expressed only under an absolute state of rest. Our results support the idea that the presence of the DGE may be underestimated in other insect taxa because they may have been measured under conditions where this pattern not necessarily can be expressed.

[Development and population parameters of cohorts of the Chilean recluse spider Loxosceles laeta]. / Desarrollo de cohortes y parámetros poblacionales de la araña del rincón Loxosceles laeta.

BACKGROUND: Despite the abundant eco-epidemiological knowledge of the Chilean reclusive spider, Loxosceles laeta, which causes all forms of loxoscelism in Chile, the main characteristics of this species its stages of development remains poorly known especially in the medical area. OBJECTIVE: In this study we address these issues with the goal of providing clear images of the development of this species and for the first time on population projections as well as the relationship between mature and immature instars, useful data for the control and prevention of accidental bites. RESULTS: We found that L. laeta is an r-selected species, with R0=2.1, a generation time of G=2.1 years, with a concentration of the reproductive value of females between the first and second year of life. We determined the average sizes and development times of all instars. The first vary between 2.3 mm at birth and about 13 mm at adulthood. The total development time was about 1 year. DISCUSSION: The population projection by Leslie matrix suggested great capacity for growth and dispersal with clear seasonal population fluctuations associated with reproduction. It also showed that the proportion of immature varied seasonally between 80 and 90 %, which means that a house with three or four visible adult spiders actually has a population between 20 and 40 spiders in total.

[Pneumonia in the inmunocompromised host: perspective through images diagnosis and a Bayesian inference]. / Neumonías en el inmunocomprometido: perspectiva desde el diagnóstico por imágenes, e inferencia Bayesiana.

INTRODUCTION: The population of immunocompromised patients has increased in recent decades. Many of these patients eventually present infectious complications including pneumonia, which is a diagnostic that must to be prompt and accurate. OBJECTIVE: To review the basis of the diagnosis of pneumonia in the immunocompromised patient. Sorted by the methodology of Bayesian inference, very relevant in the diagnostic attribution, we review the main basis of the diagnosis of pneumonia of immunocompromised patients: the epidemiology, the clinical history including the type of immunosuppression that weigh the likelihood of attribution a priori of an etiologic agent, and finally, the findings in the image (or likelihood function). CONCLUSION: Although in general the findings are not pathognomonic and there is much overlap in the images, there are several features that orient in one direction or another. Proper assessment of the prior probability and the likelihood function is allowing ultimately a good diagnostic proposition.

Parasite Burden of Trypanosoma cruzi in Whole Blood and Buffy Coat Determined by Real-Time PCR in Individuals with Chronic Chagas Disease.

The objective of this study was to compare, by qPCR, the circulating blood parasite load of Trypanosoma cruzi in the buffy coat, and in whole blood mixed with boiled and unboiled guanidine hydrochloride-EDTA buffer, of individuals with chronic ChD. The concentration and purity of DNA were evaluated in a Nanodrop Denovix DS-11FX Series Spectrophotometer (DeNovix Inc., Wilmington, NC, USA). The parasite load was determined with the Taqman® qPCR system using a Stratagene Mx3000P thermocycler (Agilent Technologies, Santa Clara, CA, USA) with Cruzi 1 and Cruzi 2 satellite primers. Student's t-test with Bonferroni correction, Chi-squared (χ2) tests and Spearman's correlation coefficient were applied. The concentration and purity of DNA were higher in the buffy coat. Parasite DNA was detected and quantifiable in the three types of samples in seven patients, without statistically significant differences in the parasite load obtained. Higher correlations were found between the total DNA concentrations and the parasite loads obtained in the samples of the buffy coat.

Nowcasting methods to improve the performance of respiratory sentinel surveillance: lessons from the COVID-19 pandemic.

Respiratory diseases, including influenza and coronaviruses, pose recurrent global threats. This study delves into the respiratory surveillance systems, focusing on the effectiveness of SARI sentinel surveillance for total and severe cases incidence estimation. Leveraging data from the COVID-19 pandemic in Chile, we examined 2020-2023 data (a 159-week period) comparing census surveillance results of confirmed cases and hospitalizations, with sentinel surveillance. Our analyses revealed a consistent underestimation of total cases and an overestimation of severe cases of sentinel surveillance. To address these limitations, we introduce a nowcasting model, improving the precision and accuracy of incidence estimates. Furthermore, the integration of genomic surveillance data significantly enhances model predictions. While our findings are primarily focused on COVID-19, they have implications for respiratory virus surveillance and early detection of respiratory epidemics. The nowcasting model offers real-time insights into an outbreak for public health decision-making, using the same surveillance data that is routinely collected. This approach enhances preparedness for emerging respiratory diseases by the development of practical solutions with applications in public health.

Northern and central Chile still free of emerging flaviviruses in mosquitoes (Diptera: Culicidae).

Geographic isolation and strict control limits in border areas have kept Chile free from various pathogens, including Flavivirus. However, the scenario is changing mainly due to climate change, the reintroduction of more aggressive mosquitoes, and the great wave of migration of people from endemic countries in recent years. Hence, it is necessary to surveillance mosquitoes to anticipate a possible outbreak in the population and take action to control it. This study aimed to investigate the presence of Flavivirus RNA by molecular tools with consensus primers in mosquitoes collected in the extreme north and central Chile. From 2019 to 2021, a prospective study was carried out in localities of Northern and part of Central Chile. Larvae, pupae, and adults of mosquitoes were collected in rural and urban sites in each locality. The collected samples were pooled by species and geographical location and tested using RT-PCR and RT-qPCR to determine presence of Flavivirus. 3085 specimens were collected, the most abundant specie Culex quinquefasciatus in the North and Aedes (Ochlerotatus) albifasciatus in the Center of Chile. Both genera are associated with Flavivirus transmission. However, PCR and RT-PCR did not detect Flavivirus RNA in the mosquitoes studied. These negative results indicate we are still a free Flavivirus country, which is reaffirmed by the non-existence of endemic human cases. Despite this, routine surveillance of mosquitoes and the pathogens they carry is highly recommended to evaluate each area-specific risk of vector-borne transmission.

[Epidemiological dynamics of Dengue on Easter Island]. / Dinámica epidemiológica del dengue en Isla de Pascua.

Dengue is considered an emerging disease with an increasing prevalence especially in South America. In 2002, an epidemic of classic Dengue (DENV-1) occurred unexpectedly on Easter Island, where it had never been detected before. It reappeared in 2006-2007 and 2008, 2009 and 2011. The aim of this study was to estimate the most relevant parameters of the epidemiological dynamics of transmission of Dengue on Easter Island and to model the dynamics since 2002, comparing the predictions with the actual situation observed. Of the total cases, 52.27% were females and 47.73% men. The average age of infection was 31.38 ± 18.37 years, similar in men and women. We estimated the reproductive number R0 = 3.005 with an IC0,95 = [1.92, 4.61]. The inter-epidemic period reached an estimated T = 5.20 to 6.8 years. The case simulation showed recurrent epidemics with decreasing magnitude (damped oscillations), which is a known phenomenon in models of dengue and malaria. There was good qualitative fit to the epidemiological dynamics from 2002 onwards. It accurately predicted the rise in cases between 2006 and 2011. The predicted number of cases during the 2002 epidemic is greater than the confirmed cases and the predicted epidemic was faster than notified cases. Interepidemic period in the simulation was 6.72 years between 2002 and 2008 and 4.68 years between 2008 and 2013. From the theoretical perspective, the first epidemic had affected 94% of the population (approximately 3500 cases), but 639 were reported suggesting underreporting and a lot of sub-clinical cases occurred. Future epidemic of decreasing size are expected, although the main danger are epidemics of hemorrhagic dengue fever resulting from the introduction of different dengue virus serotypes.

How accurate are radiography and computed tomography in the diagnosis of COVID-19?-A Bayesian approach.

Background: The role of radiology in patients with clinical suspicion of COVID-19 is evolving with scientific evidence, but there are differences in opinion on when and how the technique should be used for clinical diagnosis. Purpose: To estimate the pre-test and post-test probability that a patient has COVID-19 in the event of a positive and/or negative result from chest X-ray and chest computed tomography (CT) radiological studies, comparing with those of real time polymerase chain reaction (RT-PCR) tests. Methods: The literature on the sensitivity and specificity of the chest X-ray, chest CT, and RT-PCR was reviewed. Based on these reported data, the likelihood ratios (LR) were estimated and the pre-test probabilities were related to the post-test probabilities after positive or negative results. Results: The chest X-ray has only a confirmatory value in cases of high suspicion. Chest CT analyses showed that when it is used as a general study, it has almost confirmatory value under high clinical suspicion. A chest CT classified with CO-RADS ≥ 4 has almost a diagnostic certainty of COVID-19 even with moderate or low clinical presumptions, and the CO-RADS 5 classification is almost pathognomonic before any clinical presumption. To rule out COVID-19 completely is only possible in very low clinical assumptions with negative RT-PCR and/or CT. Conclusions: Chest X-ray and especially CT are fast studies that have the capacity to report high probability of COVID-19, being a real contribution to the concept of "probable case" and allowing support to be installed in an early and timely manner.

Chagas disease in northern Chile: Detection of Trypanosoma cruzi in children, dogs and triatomine bugs.

Chagas disease is an anthropozoonotic disease caused by the protozoan Trypanosoma cruzi, transmitted by triatomine vectors. In Chile, there are four species of triatomine bugs that are potential vectors of T. cruzi, being Triatoma infestans the main vector in endemic areas of the country. The "Programa Nacional de Control Vectorial de la Enfermedad de Chagas de Chile" has significantly reduced the rates of home infestation to less than 1% and has interrupted vectorial transmission since 1999. The objective of this study was to evaluate the impact of vectorial control and the continuity of the interruption of vectorial transmission in northern Chile (provincia de El Loa, región de Antofagasta). The study comprised fingerstick blood samples of 2104 children, attending local school, venous blood samples of 65 dogs, associated to houses with T. infestans unique findings and vector infestation, and intestine samples of 284 T. infestans specimens, from the provincia de El Loa, during 2014-2016 period. The samples were analyzed by enzyme-linked immunosorbent assay (ELISA), indirect immunofluorescence and/or polymerase chain reaction (PCR) techniques. A total of 5 children (0.24%), 7 dogs (10.8%), and 6 specimens of T. infestans (2.1%) resulted positive to T. cruzi infection. This study showed that the risk of transmission of Chagas disease is low in the north of Chile (provincia de El Loa), detected a low positive rate of chagasic children and of infected triatomine bugs, and showed the existence of T. cruzi transmission in dogs, which are used as natural sentinels for the detection of T. cruzi infection, being especially useful during surveillance program in human population characterized by low seroprevalence.

COVID-19 in Chile: The usefulness of simple epidemic models in practice. / COVID-19 en Chile: la utilidad de los modelos epidémicos simples en la práctica.

OBJECTIVES: The purpose of this article is to describe and develop the predictive value of three models during the COVID-19 epidemic in Chile, providing knowledge for decision-making in health. METHODS: We developed three models during the epidemic: a discrete model to predict the maximum burden on the health system in a short time framea basic SEIR (susceptible-exposed-infected-removed) model with discrete equations; a stochastic SEIR model with the Monte Carlo method; and a Gompertz-type model for metropolitan city of Santiago. RESULTS: The maximum potential burden model has been useful throughout the monitoring of the epidemic, providing an upper bound for the number of cases, intensive care unit occupancy, and deaths. Deterministic and stochastic SEIR models were very useful in predicting the rise of cases and the peak and onset of case decline; however, they lost utility in the current situation due to the asynchronous recruitment of cases in the regions and the persistence of a strong endemic. The Gompertz model had a better fit in the decline since it best captures the epidemic curves asymmetry in Santiago. CONCLUSIONS: The models have shown great utility in monitoring the epidemic in Chile, with different objectives in different epidemic stages. They have complemented empirical indicators such as reported cases, fatality, deaths, and others, making it possible to predict situations of interest and visualization of the short and long-term local behavior of this pandemic.

OBJETIVOS: El objetivo general ha sido describir y evaluar el valor predictivo de tres modelos durante el desarrollo de la epidemia COVID-19 en Chile, aportando conocimiento para la toma de decisiones en salud. MÉTODOS: Desarrollamos tres modelos a lo largo de la epidemia: un modelo discreto para predecir a corto tiempo la máxima carga sobre el sistema de salud, un modelo básico SEIR (susceptibles-expuestos-infectados-removidos) con ecuaciones discretas; un modelo SEIR estocástico con método de Montecarlo; y un modelo de tipo Gompertz para la Región Metropolitana (Santiago). RESULTADOS: El modelo de máxima carga potencial ha sido útil durante todo el seguimiento de la epidemia proporcionando una cota superior para el número de casos, la ocupación de unidades de cuidados intensivos y el número de fallecidos. Los modelos SEIR determinístico y estocástico tuvieron gran utilidad en la predicción del ascenso de los casos, el máximo y el inicio del descenso de casos, perdiendo utilidad en la situación actual por el reclutamiento asincrónico de casos en las regiones y la persistencia de una endemia alta. El modelo de Gompertz ha tenido un mejor ajuste en el descenso ya que esta captura mejor la asimetría de la curva epidémica en Santiago. CONCLUSIONES: Los modelos han demostrado gran utilidad en el seguimiento de la epidemia en Chile, con distintos objetivos en distintas etapas de la epidemia. Han complementado los indicadores empíricos como casos reportados, letalidad, fallecimientos y otros, permitiendo predecir situaciones de interés y visualizar la conducta a corto y largo plazo de esta pandemia a nivel local.

[Distribution and risk factors of human cystic echinococcosis in Aysén 2010-2016]. / Distribución y factores de riesgo de equinococosis quística humana en Aysén 2010-2016.

BACKGROUND: In Chile, cystic echinococcosis is endemic throughout the country and hyperendemic in some regions such as La Araucanía and Aysén and continues to be a neglected public health problem. AIM: To estímate the risk of human hydatidosis in Aysén, studying the relationship of notifications and hospital discharge rates with social and environmental factors, such as population, multidimensional poverty index, urbanization, average temperature, average rainfall and sheep population. METHODS: Poisson regressions were used to study the factors associated with notifiable diseases and hospital discharge rates and the Besag-York-Mollie model for relative risk. RESULTS AND CONCLUSIONS: Aysén has a high risk, between 2 and 19 times that expected for the region. A significant underreporting of cases was found. The model of hospital discharges had a good fit showing the positive influence of the human and bovine population and the positive effect of temperature. An effect of the multidimensional poverty index was also detected, which is mainly affected by education and working conditions. Excepting one locality, the areas of greatest risk correspond to the eastern cordon of the Aysén region.

Temporal and geographic analysis of trichinellosis incidence in Chile with risk assessment.

Trichinellosis is a foodborne disease caused by several Trichinella species around the world. In Chile, the domestic cycle was fairly well-studied in previous decades, but has been neglected in recent years. The aims of this study were to analyze, geographically, the incidence of trichinellosis in Chile to assess the relative risk and to analyze the incidence rate fluctuation in the last decades. Using temporal data spanning 1964-2019, as well as geographical data from 2010 to 2019, the time series of cases was analyzed with ARIMA models to explore trends and periodicity. The Dickey-Fuller test was used to study trends, and the Portmanteau test was used to study white noise in the model residuals. The Besag-York-Mollie (BYM) model was used to create Bayesian maps of the level of risk relative to that expected by the overall population. The association of the relative risk with the number of farmed swine was assessed with Spearman's correlation. The number of annual cases varied between 5 and 220 (mean: 65.13); the annual rate of reported cases varied between 0.03 and 1.9 cases per 105 inhabitants (mean: 0.53). The cases of trichinellosis in Chile showed a downward trend that has become more evident since the 1980s. No periodicities were detected via the autocorrelation function. Communes (the smallest geographical administrative subdivision) with high incidence rates and high relative risk were mostly observed in the Araucanía region. The relative risk of the commune was significantly associated with the number of farmed pigs and boar (Sus scrofa Linnaeus, 1758). The results allowed us to state that trichinellosis is not a (re)emerging disease in Chile, but the severe economic poverty rate of the Mapuche Indigenous peoples and the high number of backyard and free-ranging pigs seem to be associated with the high risk of trichinellosis in the Araucanía region.