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.

Análisis espacio-temporal de la tuberculosis pulmonar para el periodo 2016-2020 en la Región Metropolitana, Chile

Introducción: El año 2020, la tuberculosis (TB) fue responsable por 9,9 millones de nuevos casos y 1,5 millones de muertes en el mundo. En Chile, se ha reportado aumento en las tasas de incidencia en los últimos años, con gran concentración de casos en la Región Metropolitana (RM). Objetivo: Evaluar la relación espacio-temporal de la TB pulmonar con variables socioeconómicas en la RM de Chile. Material y Método: Estudio ecológico desarrollado entre los años 2016 y 2020. Los casos se obtuvieron desde el Ministerio de Salud (n = 4.370), describiéndose según: sexo, edad, año de confirmación diagnóstica, servicio de salud y comuna de residencia. Se utilizó análisis de componentes principales para la construcción de factores socioeconómicos comunales. La asociación entre factores y TB pulmonar se evaluó con un modelo binominal negativo multinivel. Resultados: Se observó aumento en la tasa de incidencia (9,97 a 10,74 casos por 100 mil), disminución de la incidencia en personas ≥ 65 años (17,56 a 13,38) y en el promedio de edad (46,03 a 41,77 años). El factor caracterizado por mayor inmigración, hacinamiento y población urbana se asoció con mayores tasas de incidencia (RTI: 1,29; IC95: 1,23-134) y el factor con mayor escolaridad, menor pobreza y menor hacinamiento con menores tasas (RTI: 0,94; IC95: 0,89-0,98) en el periodo. Conclusiones: La disminución en la edad de los casos junto a la concentración de casos en comunas urbanas y céntricas, asociadas con variables socioeconómicas desfavorables, confirman que la TB pulmonar continúa siendo un problema de relevancia a considerar.

Background: In 2020, tuberculosis (TB) was responsible for 9.9 million new cases and 1.5 million deaths worldwide. In Chile, an increase in incidence rates has been reported in recent years, with a concentration of cases in the Metropolitan Region (MR). Aim: To evaluate the spatio-temporal relationship of pulmonary TB with socioeconomic variables in the MR of Chile. Methods: Ecological study developed between 2016 and 2020. Cases were obtained from the Ministry of Health (n = 4,370) and described by: sex, age, year of confirmation, health service, and commune of residence. Principal component analysis was used to construct community socioeconomic factors, and the association between factors and pulmonary TB was evaluated with a multilevel negative binomial model. Results: There was an increase in the incidence rate (9.97 to 10.74 cases per 100,000), a decrease in the incidence in people ≥ 65 years (17.56 to 13.38), and the average age (46.03 to 41.77 years). The factor characterized by greater immigration, overcrowding, and the urban population was associated with more elevated incidence rates (RTI: 1.29; IC95: 1.23-134), and the factor with higher education, less poverty, and less overcrowding with lower rates (RTI: 0.94; CI 95: 0.89-0.98) in the period. Conclusions: The decrease in the age of the cases together and the concentration of cases in urban and central communes, associated with unfavorable socioeconomic variables, confirm that pulmonary TB continues to be a relevant problem to consider.

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.

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.

[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.

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.

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

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.

[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.

Clinical, electrocardiographic and echocardiographic evolution of chronic Chagas disease treated with nifurtimox on prolonged follow-up in Chile: observational study.

OBJECTIVES: This study aimed to describe the electrocardiographic and echocardiographic status of chronic Chagas disease (cChD) patients treated with nifurtimox. METHODS: An observational study was performed in 146 cChD patients followed over a mean of 7.9 years. RESULTS: Of the 146 patients, 41 (28.1%) with normal electrocardiogram (ECG) at baseline maintained this condition, 34 (23.3%) with altered ECG at baseline normalised the alterations, and 46 (31.5%) with ECG abnormalities at baseline maintained this condition [23 (15.8%) with small alterations]. Finally, 25 cases (17.1%) in indeterminate phase altered the ECG. Differences before and after follow-up (P < 0.001) were found. The percentage of beneficial treatment was different than expected by chance (Z = 4.8; P < 0.001) and the annual percentage of cases that developed ECG alterations was lower than that of a historical cohort of untreated patients (P < 0.001). An echocardiogram was performed in 68 patients with baseline ECG alterations. The ejection fraction (EF) was normal in 57 (83.8%) and abnormal in 11 (16.2%). In 38 patients with ECG abnormalities that did not progress after treatment, EF and segmental motility (SM) were normal in 31 (81.6%) and 26 (68.4%), respectively. In 17 patients with ECG abnormalities, EF and SM were normal in 15 (88.2%) and 14 (82.4%) cases, respectively. CONCLUSION: Less progression to cardiomyopathy compared with a historical untreated cohort as well as the EF/SM results in patients with abnormal ECG that did not progress and in indeterminate cChD that altered the ECG suggests a beneficial effect of nifurtimox.

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

INTRODUCCIÓN: En Chile, la equinococosis quística o hidatidosis es endémica a lo largo de todo el país e hiperendémica en algunas regiones como La Araucanía y Aysén y sigue siendo un problema de salud pública desatendido. OBJETIVO: Estimar el riesgo de hidatidosis humana en Aysén, estudiando la relación de las notificaciones y egresos con factores sociales y ambientales, tales como población, índice de pobreza multidimensional, urbanización, temperatura media, precipitación media y población ganadera ovina. METODOLOGÍA: Se utilizaron regresiones de Poisson para estudiar los factores asociados a enfermedades de notificación obligatoria y egresos y el modelo Besag-York-Mollie para el riesgo relativo. RESULTADOS Y CONCLUSIONES: Aysén tiene un alto riesgo de hidatidosis humana, entre 2 y 19 veces el esperado para la región. Se encontró una importante sub-notificación de casos. El modelo de los egresos hospitalarios tuvo un buen ajuste mostrando la influencia positiva de la población humana y ovina y el efecto positivo de la temperatura. También se detectó un efecto del índice de pobreza multidimensional sobre los casos y egresos hospitalarios, que es principalmente afectado por la educación y de condiciones de trabajo. Exceptuando la comuna de O'Higgins, las zonas de mayor riesgo corresponden al cordón oriental de la Región de Aysén.

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.

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.

Changes in Age and Geographic Distribution of the Risk of Chagas Disease in Chile from 1989 to 2017.

The interruption of vector-borne transmission of Chagas disease was certified in Chile in 1999. Our goal was to determine the effects of the interruption of vector transmission on the age and spatial distributions of the risk of Chagas disease. We analyzed cases of Chagas disease by age and sex between 1989 and 2017, from notified disease reports of the Ministry of Health. Bayesian risk maps were constructed using the Besag-York-Mollie model. The reported cases of Chagas disease had a mean age of 45.9 ± 17.6 years. Small changes in the age distribution were found among different periods (χ215 = 602.4, p < 0.001). These were explained mainly by numbers lower than those expected in age groups 0-39 years in the 2011-2017 period. Part of the observed reduction in the proportion of individuals in the lower strata could be explained by the aging of the Chilean population. An increase of reported cases was detected after the interruption of vector-borne transmission (F1,327 = 4.24, p < 0.04), with regional differences (F14,1308 = 4.35, p < 0.001). The regions of the north-central area that have the highest burden of Chagas tended to decrease the relative risk, while the regions of the south tended to increase and small risk areas appear in zones where there are no insect vectors. There is still no clear evidence of a reduction in the reported cases in Chile. This could be explained mainly by an improvement in the detection of cases, but it cannot be ruled out that vector transmission still exists. The changes in distribution suggest potential impact from human internal migration and blood transfusion. This study provides strong evidence supporting the idea that entomological surveillance and long-term follow-up of Chagas disease need to be maintained after certification of interruption in endemic countries.

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

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.

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 curve's 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.

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.

[Estimation of the effective reproduction number of measles 2018-2019 in Chile]. / Estimación del número reproductivo efectivo del brote de sarampión 2018-2019 en Chile.

BACKGROUND: Measles cases are reemerging in many countries across the globe. There was an outbreak of imported measles between November 2018 and February 2019 in Chile, raising concern among the public and health authorities. Many were worried about the Chilean measles herd immunity, a factor that relates to the reproductive capacity of the virus (measure of transmissibility of a pathogen). AIM: Here we estimate the effective reproductive number (Re) of this measles outbreak. RESULTS: Although the estimate is highly uncertain due to the low number of cases and the absence of homogeneous mixing of the population, we found Re was approximately 1.5. DISCUSSION AND CONCLUSIONS: Consequently we estimated about 90,3 % had measles immunity, consistent with administrative estimates from the Ministry of Health. These results suggest the Chilean population has established herd immunity against the introduction of imported measles cases, reflecting adequate preventive management of this disease.

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

[ABSTRACT]. 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.

[RESUMEN]. 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.

Estimación del número reproductivo efectivo del brote de sarampión 2018-2019 en Chile / Estimation of the effective reproduction number of measles 2018-2019 in Chile

Resumen Introducción: Los casos de sarampión están resurgiendo en muchos países del mundo. Hubo un brote de sarampión importado entre noviembre de 2018 y febrero de 2019 en Chile, lo que generó preocupación entre el público y las autoridades sanitarias. Muchos se preocuparon por la tasa de inmunización contra el sarampión de la población, un factor que se relaciona con la capacidad reproductiva del virus (medida de transmisibilidad de un patógeno). Objetivo: Aquí estimamos el número reproductivo efectivo (Re) de este brote de sarampión. Resultados: Aunque la estimación tiene mucha incertidumbre por el bajo número de casos y la ausencia de mezcla homogénea de la población, encontramos que Re fue aproximadamente 1,5. Discusión y Conclusiones: En consecuencia estimamos que aproximadamente 90,3% de la población tiene inmunidad al sarampión, lo que coincide con las estimaciones del Ministerio de Salud. Estos resultados sugieren que la población chilena ha establecido la inmunidad colectiva contra la introducción de casos importados de sarampión, lo que refleja un manejo preventivo adecuado de esta enfermedad.

Abstract Background: Measles cases are reemerging in many countries across the globe. There was an outbreak of imported measles between November 2018 and February 2019 in Chile, raising concern among the public and health authorities. Many were worried about the Chilean measles herd immunity, a factor that relates to the reproductive capacity of the virus (measure of transmissibility of a pathogen). Aim: Here we estimate the effective reproductive number (Re) of this measles outbreak. Results: Although the estimate is highly uncertain due to the low number of cases and the absence of homogeneous mixing of the population, we found Re was approximately 1.5. Discussion and Conclusions: Consequently we estimated about 90,3 % had measles immunity, consistent with administrative estimates from the Ministry of Health. These results suggest the Chilean population has established herd immunity against the introduction of imported measles cases, reflecting adequate preventive management of this disease.

Contribution of Anthropogenic Factors and Climate Variables to Human Cystic Echinococcosis Mortality in Chile (2001-2011).

Here we assess the effect of weather and anthropogenic environmental variables, particularly urbanization, on cystic echinococcosis mortality in Chile from 2001 to 2011 using a nonparametric regression model, multivariate adaptive regression splines, and Poisson nonlinear regression models. This study integrated data from various sources on weather and anthropogenic variables. The canine population had the greatest influence on human cystic echinococcosis mortality during the period analyzed. Urbanization among anthropogenic variables and temperature and precipitation among the weather-related variables were the main factors related to cystic echinococcosis deaths. Deaths decreased with urbanization level. Temperature showed a nonlinear impact on mortality, with an optimum value ∼11°C. Public policies aimed at improving safe management of companion animal populations are crucial in controlling the spread of this disease. Effective animal management strategies would have wide-ranging public health benefits, advance the welfare of companion animals and livestock, and decrease the number of human cystic echinococcosis cases.

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.