Factors influencing neutralizing antibody response to the original SARS-CoV-2 virus and the Omicron variant in a high vaccination coverage country, a population-based study

The study compared immunity to the original SARS-CoV-2 virus (Wuhan) and the Omicron variant using neutralizing antibodies (NAbs), that provide a good approximation of protective immunity. The results might help determine immunization strategies.

DESIGN AND METHODS

Unlike previous studies, we analyzed NAbs in a random sample of 110 IgG positive sera from individuals who participated in a population-based seroprevalence transversal study, carried out in May 2022 in two Chilean cities, a country with high vaccination coverage.

RESULTS

Our findings indicate that 98.2% of individuals had NAbs against Wuhan, 65.5% against Omicron, and 32.7% tested positive for Wuhan but not Omicron. Factors influencing protective immunity included a prior natural infection and the number of vaccines received. NAbs titers against the original virus were high, demonstrating vaccine effectiveness in the population. However, the level of antibodies decreased when measuring NAbs against Omicron, particularly among older individuals, indicating a decline in vaccine protection. Previous COVID-19 episodes acted as a natural booster, increasing NAbs titers against both virus strains.

CONCLUSIONS

Protective immunity against the original Wuhan SARS-CoV-2 virus is reduced when compared to Omicron variant. Updating vaccine to target emerging variants and continued monitoring of effectiveness at the population level are necessary.

Exposure of 4-year to 24-year olds to tobacco imagery on prime-time Chilean television

INTRODUCTION

The extent of the population's exposure to tobacco imagery across all genres of regular TV programming and the contribution of each of these genres is unknown, except for UK broadcast channels. The objective of this study is to estimate the exposure of young people to tobacco imagery on Chilean prime-time television and the programme source contributing to such exposure.

METHODS

Programmes aired during 3 weeks in 2019 from the 15 highest audience channels in Chile were content-analysed for the occurrence of tobacco categorised as actual use, implied use, tobacco paraphernalia, tobacco brand appearances and whether they violated Chilean smoke-free law for each 1 min interval (92 639). The exposure of young people to tobacco content was estimated using media viewership figures.

RESULTS

Young people received 29, 11 and 4 million tobacco impressions of any type, explicit use and smoke-free violation, respectively, at a rate of 21.8, 8.0 and 2.1 thousand impressions per hour of TV viewing. The main sources of exposure to tobacco impressions were feature films and animated productions, which were almost entirely non-Chilean. Finally, young people were exposed to tobacco brand impressions primarily through films, effectively circumventing the advertising ban in Chile.

DISCUSSION

Television programming is a source of significant youth exposure to tobacco imagery, including branding impressions. To conform to the WHO FCTC, Chile should prohibit tobacco branding in any TV programme and require strong anti-tobacco advertisements prior to any TV programme portraying tobacco.

Seroprevalence of Natural and Acquired Immunity against the SARS-CoV-2 Virus in a Population Cohort from Two Chilean Cities, 2020-2022

BACKGROUND

Chile has achieved the highest coverage for vaccines against the SARS-CoV-2 virus worldwide.

OBJECTIVE

To assess the progression of immunity (natural and acquired by vaccine) in a cohort from two Chilean cities.

METHODS

Individuals (n = 386) who participated in three phases of population-based serial prevalence studies were included (2020-2021 and 2022). Presence of SARS-CoV-2 antibodies was measured in serum. Data including time of vaccination and type of vaccine received were analysed with descriptive statistics.

RESULTS

Seroprevalence was 3.6% in the first round and increased to 96.9% in the second and 98.7% in the third. In the third round, 75% of individuals who had received the basal full scheme were seropositive at 180 days or more since their last dose; 98% of individuals who received one booster dose were seropositive at 180 days or more, and 100% participants who received two boosters were seropositive, regardless of time since their last dose. Participants receiving mRNA vaccines had higher seroprevalence rates over time.

CONCLUSIONS

The high vaccination coverage in Chile enabled the population to maintain high levels of antibodies. Vaccination boosters are essential to maintain immunity over time, which also depends on the type of vaccine administered.

Exposure to tobacco impressions during prime-time TV among Chilean minors by sex and socioeconomic status

INTRODUCTION

We tested if tobacco impressions were delivered differentially to prime-time TV watching minors by sex and socioeconomic status.

METHODS

Programs aired during prime-time for three random weeks in 2019 from the 15 highest audience channels in Chile were content-analyzed for the occurrence of tobacco for each one-minute interval of 92639 recorded. Such occurrences were categorized as actual use and whether they violated Chilean smoke-free law or tobacco brand appearances. We estimated the number of persons per hour (p/h) exposed to tobacco impressions for the 4 to 17 years age group by sex and socioeconomic status (SES).

RESULTS

Minors spent over a billion p/h watching TV during the observation period. Minors were exposed to tobacco explicit use, branding and smoke-free violation impressions for 9.7 million, 1.2 million, and 1.0 million p/h, respectively. The odds ratios (OR) of exposure to total tobacco impressions were always greater among boys with higher SES compared to boys with low SES. However, they were greater among girls of low SES compared to those of high SES for all types of impressions. The OR of exposure to tobacco branding was higher among girls of any SES compared to boys of any SES.

CONCLUSIONS

Minors need protection from tobacco imagery on television, particularly girls of low SES. To that end, new legislation should implement all measures to counter depictions of tobacco in entertainment media, as recommended in the WHO FCTC Article 13 guidelines. This should require strong anti-tobacco advertisements before any TV program portraying tobacco targeting minor audiences, particularly girls of low SES. Given that Chile has one of the highest prevalences in the world of current cigarette smoking among young females, the potential contribution of tobacco impressions on TV to smoking differentials across female socioeconomic groups should be further studied.

Quality of life and cost-effectiveness analysis of topical tranexamic acid and fibrin glue in femur fracture surgery

Background

We assessed quality of life (QoL) of patients undergoing surgery for proximal femur fracture and performed a cost-effectiveness analysis of haemostatic drugs for reducing postoperative bleeding.

Methods

We analysed data from an open, multicentre, parallel, randomized controlled clinical trial (RCT) that assessed the efficacy and safety of tranexamic acid (TXA group) and fibrin glue (FG group) administered topically prior to surgical closure, compared with usual haemostasis methods (control group).

For this study we conducted a cost-effectiveness analysis of these interventions from the Spanish Health System perspective, using a time horizon of 12 months. The cost was reported in $US purchasing power parity (USPPP). We calculated the incremental cost-effectiveness ratio (ICER) per QALY (quality-adjusted life-year).

Results

We included 134 consecutive patients from February 2013 to March 2015: 42 patients in the TXA group, 46 in the FG group, and 46 in the control group. Before the fracture, EuroQol visual analogue scale (EQ-VAS) health questionnaire score was 68.6. During the 12 months post-surgery, the intragroup EQ-VAS improved, but without reaching pre-fracture values.

There were no differences between groups for EQ-VAS and EuroQol 5 dimensions 5 levels (EQ-5D-5L) health questionnaire score, nor in hospital stay costs or medical complication costs. Nevertheless, the cost of one FG treatment was significantly higher (399.1 $USPPP) than the cost of TXA (12.9 $USPPP) or usual haemostasis (0 $USPPP).

When comparing the cost-effectiveness of the interventions, FG was ruled out by simple dominance since it was more costly (13,314.7 $USPPP) than TXA (13,295.2 $USPPP) and less effective (utilities of 0.0532 vs. 0.0734, respectively). TXA compared to usual haemostasis had an ICER of 15,289.6 $USPPP per QALY).

Conclusions

There were no significant differences between the intervention groups in terms of postoperative changes in QoL. However, topical TXA was more cost-effective than FG or usual haemostasis.

Trial registration

ClinicalTrials.gov: NCT02150720. Date of registration 30/05/2014. Retrospectively registered.

First wave of SARS-CoV-2 in Santiago Chile: Seroprevalence, asymptomatic infection and infection fatality rate

BACKGROUND

The first wave of SARS-CoV-2 infection in Chile occurred during the cold season reaching a peak by the end of June 2020, with 80 % of the cases concentrated in its capital, Santiago. The main objective of this study was to estimate the attack rate during this first wave of SARS-CoV-2 in a large, densely populated city with more than seven million inhabitants. Since the number of confirmed cases provides biased information due to individuals' potential self-selection, mostly related to asymptomatic patients and testing access, we measured antibodies against SARS-CoV-2 to assess infection prevalence during the first wave in the city, as well as estimate asymptomatic cases, and infection fatality ratio. To our knowledge this is one of the few population-based cross-sectional serosurvey during the first wave in a highly affected emerging country. The challenges of pandemic response in urban settings in a capital city like Santiago, with heterogeneous subpopulations and high mobility through public transportation, highlight the necessity of more accurate information regarding the first waves of new emerging diseases.

METHODS

From April 24 to June 21, 2020, 1326 individuals were sampled from a long-standing panel of household representatives of Santiago. Immunochromatographic assays were used to detect IgM and IgG antibody isotypes.

RESULTS

Seroprevalence reached 6.79 % (95 %CI 5.58 %-8.26 %) in the first 107 days of the pandemic, without significant differences among sex and age groups; this figure indicates an attack rate 2.8 times higher than the one calculated with registered cases. It also changes the fatality rate estimates, from a 2.33 % case fatality rate reported by MOH to an estimated crude 1.00 % (CI95 % 0.97-1.03) infection fatality rate (adjusted for test performance 1.66 % [CI95 % 1.61-1.71]). Most seropositive were symptomatic (81,1 %).

CONCLUSIONS

Despite the high number of cases registered, mortality rates, and the stress produced over the health system, the vast majority of the people remained susceptible to potential new epidemic waves. We contribute to the understanding of the initial spread of emerging epidemic threats. Consequently, our results provide better information to design early strategies that counterattack new health challenges in urban contexts.

SARS-CoV-2 Neutralizing Antibodies in Chile after a Vaccination Campaign with Five Different Schemes

Using levels of neutralizing antibodies (nAbs), we evaluate the successful Chilean SARS-CoV-2 vaccine campaign, which combines different vaccine technologies and heterologous boosters. From a population-based study performed in November 2021, we randomly selected 120 seropositive individuals, organized into six groups of positive samples (20 subjects each) according to natural infection history and the five most frequent vaccination schemes. We conclude that the booster dose, regardless of vaccine technology or natural infection, and mRNA vaccines significantly improve nAbs response.

Immunization and SARS-CoV-2 Antibody Seroprevalence in a Country with High Vaccination Coverage: Lessons from Chile

Chile is among the most successful nations worldwide in terms of its COVID-19 vaccine rollout. By 31 December 2021, 84.1% of the population was fully vaccinated, and 56.1% received booster doses using different COVID-19 vaccines. In this context, we aimed to estimate the prevalence of anti-SARS-CoV-2 antibodies following the infection and vaccination campaign. Using a three-stage stratified sampling, we performed a population-based cross-sectional serosurvey based on a representative sample of three Chilean cities. Selected participants were blood-sampled on-site and answered a short COVID-19 and vaccination history questionnaire using Wantai SARS-CoV-2 Ab ELISA to determine seroprevalence. We recruited 2198 individuals aged 7–93 between 5 October and 25 November 2021; 2132 individuals received COVID-19 vaccinations (97%), 67 (3.1%) received one dose, 2065 (93.9%) received two doses, and 936 received the booster jab (42.6%). Antibody seroprevalence reached 97.3%, ranging from 40.9% among those not vaccinated to 99.8% in those with booster doses (OR = 674.6, 154.8–2938.5). SARS-CoV-2 antibodies were associated with vaccination, previous COVID-19 diagnosis, age group, and city of residence. In contrast, we found no significant differences in the type of vaccine used, education, nationality, or type of health insurance. We found a seroprevalence close to 100%, primarily due to the successful vaccination program, which strongly emphasizes universal access.

Seroprevalence and estimation of the impact of SARS-CoV-2 infection in older adults residing in Long-term Care Facilities in Chile

Introduction

Older adults are at a higher risk of severe illness and death from COVID-19. This vulnerability increases in those who live in long-term care facilities due to overcrowding, greater physical dependence, and contact with health workers. Evidence on the impact of the pandemic on these establishments in lowand middle-income countries has been scant. This study aims to determine the seroprevalence of SARS-CoV-2 in older people residing in long-term care facilities and estimate the impact of infection after the first wave of the pandemic.

Methods

A cross-sectional design with 2099 residents in three regions of Chile was carried out between September and November 2020. Measurement of antibodies was performed with a rapid test. The impact of SARS-CoV-2 infection was estimated with seropositive residents, those who had a history of positive polymerase chain reaction tests, and those who died from COVID-19. Bivariate analysis with the region, sex, age, history of COVID-19, physical dependence, and serological results were performed. In addition, we performed a correlation analysis between the seroprevalence of the centers by the municipality and the rate of confirmed cases.

Results

The seroprevalence of SARS-CoV-2 antibodies in the three regions was 14.7% (95% confidence interval: 13.2 to 16.3%), the infection impact was 46.4%, and the fatality rate was 19.6%. A significant correlation was found between the seroprevalence of older adults residing in long-term care facilities and the cumulative incidence by municipalities.

Conclusions

The seroprevalence of older adults residing in long-term care facilities was higher than the general population. The high impact of infection among this population at the end of the first wave of the COVID-19 pandemic is similar to other countries. The centers' environment is directly related to COVID-19 infection. Morbidity and mortality monitoring systems should be implemented promptly to establish prevention and control measures.

Seroprevalence, spatial distribution, and social determinants of SARS-CoV-2 in three urban centers of Chile

BACKGROUND

Seroprevalence studies provide an accurate measure of SARS-CoV-2 spread and the presence of asymptomatic cases. They also provide information on the uneven impact of the pandemic, pointing out vulnerable groups to prioritize which is particularly relevant in unequal societies. However, due to their high cost, they provide limited evidence of spatial spread of the pandemic specially in unequal societies. Our objective was to estimate the prevalence of SARS-CoV-2 antibodies in Chile and model its spatial risk distribution.

METHODS

During Oct-Nov 2020, we conducted a population-based serosurvey in Santiago, Talca, and Coquimbo-La Serena (2493 individuals). We explored the individual association between positive results and socio-economic and health-related variables by logistic regression for complex surveys. Then, using an Empirical Bayesian Kriging model, we estimated the infection risk spatial distribution using individual and census information, and compared these results with official records.

RESULTS

Seroprevalence was 10.4% (95% CI 7.8-13.7%), ranging from 2% (Talca) to 11% (Santiago), almost three times the number officially reported. Approximately 36% of these were asymptomatic, reaching 82% below 15 years old. Seroprevalence was associated with the city of residence, previous COVID-19 diagnosis, contact with confirmed cases (especially at household), and foreign nationality. The spatial model accurately interpolated the distribution of disease risk within the cities finding significant differences in the predicted probabilities of SARS-CoV-2 infection by census zone (IQR 2.5-15.0%), related to population density and education.

CONCLUSIONS

Our results underscore the transmission heterogeneity of SARS-CoV-2 within and across three urban centers of Chile. Socio-economic factors and the outcomes of this seroprevalence study enable us to identify priority areas for intervention. Our methodological approach and results can help guide the design of interdisciplinary strategies for urban contexts, not only for SARS-CoV-2 but also for other communicable diseases.

Bacterial Gut Microbiota and Infections During Early Childhood

Gut microbiota composition during the first years of life is variable, dynamic and influenced by both prenatal and postnatal factors, such as maternal antibiotics administered during labor, delivery mode, maternal diet, breastfeeding, and/or antibiotic consumption during infancy. Furthermore, the microbiota displays bidirectional interactions with infectious agents, either through direct microbiota-microorganism interactions or indirectly through various stimuli of the host immune system. Here we review these interactions during childhood until 5 years of life, focusing on bacterial microbiota, the most common gastrointestinal and respiratory infections and two well characterized gastrointestinal diseases related to dysbiosis (necrotizing enterocolitis and Clostridioides difficile infection). To date, most peer-reviewed studies on the bacterial microbiota in childhood have been cross-sectional and have reported patterns of gut dysbiosis during infections as compared to healthy controls; prospective studies suggest that most children progressively return to a "healthy microbiota status" following infection. Animal models and/or studies focusing on specific preventive and therapeutic interventions, such as probiotic administration and fecal transplantation, support the role of the bacterial gut microbiota in modulating both enteric and respiratory infections. A more in depth understanding of the mechanisms involved in the establishment and maintenance of the early bacterial microbiota, focusing on specific components of the microbiota-immunity-infectious agent axis is necessary in order to better define potential preventive or therapeutic tools against significant infections in children.

Longitudinal assessment of SARS-CoV-2 IgG seroconversionamong front-line healthcare workers during the first wave of the Covid-19 pandemic at a tertiary-care hospital in Chile

Background

Healthcare workers (HCWs) are at high risk of exposure to SARS-CoV-2. Cross-sectional studies have provided variable rates of seroprevalence in HCWs. Longitudinal assessments of the serological response to Covid-19 among HCWs are crucial to understanding the risk of infection and changes in antibody titers over time. We aimed to investigate seroprevalence and risk factors associated with seroconversion in a prospective cohort of HCWs during the peak of the first wave of the Covid-19 pandemic.

Methods

We conducted a longitudinal study among 446 front-line HCWsin a tertiary-care hospital in Chile from April to July 2020. IgG was determined monthly using two different ELISAs in serum samples of HCWs, during the three-month period. In each visit, demographic data, symptoms, risk factors, and exposure risks were also assessed.

Results

The overall seroprevalence at the end of the study period was 24% (95% CI20.2–28.3), with 43% of seropositive HCWs reporting no prior symptoms. Seroconversion rates significantly differed over the study period, from 2.1% to as high as 8.8% at the peak of the epidemic. There were no statistically significant differences observed between HCWs in direct clinical care of patients with Covid-19 and those working in low risk areas. Antibody titers appeared to wane over time.

Conclusions

HCWs were severely affected with a high rate of seroconversion that appeared to mirror the local epidemiological situation. A significant amount of participants underwent an asymptomatic infection, highlighting the need for improved surveillance policies. Antibody titers appear to wane over time; further studies to understand this finding’s impact on the risk of reinfection are warranted.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06208-2.

Modelling cost-effectiveness of syphilis detection strategies in prisoners: exploratory exercise in a Chilean male prison

Background

Syphilis, together with other sexually transmitted infections, remains a global public health problem that is far from controlled. People deprived of liberty are a vulnerable population. Control activities in prisons rely mostly on passive case detection, despite the existence of affordable alternatives that would allow switching to active case-finding strategies. Our objective was to develop a mathematical modelling framework for cost-effectiveness evaluation, from a health system perspective, of different approaches using rapid tests for the detection of syphilis in inmates' populations and to explore the results based on a Chilean male prison population.

Methods

A compartmental model was developed to characterize the transmission dynamics of syphilis inside a prison with the ongoing strategy (passive case detection, with VRDL + FTA-ABS), considering the entrance and exit of inmates over a 40 year period. The model allows simulation of the implementation of a reverse algorithm for the current situation (rapid test + VDRL), different screening strategies (entry point, massive periodically; both with rapid test + VDRL) and treatment of detected cases. The parameters for the exploratory exercise were obtained from systematic searches of indexed and grey literature and field work (EQ-5D questionnaire application and key actors interviews). Probabilistic sensitivity analysis was conducted to account for uncertainty in relevant parameters.

Results

The proposed framework allows the evaluation of different detection strategies. In this study, all the strategies were cost-effective in the baseline scenario when considering an ICER threshold of 1 Chilean GDP per capita (US$15,000). The strategies most likely to be cost-effective (over 80% probability) were: current situation with reverse algorithm, entry point screening and mass screening every two years; the latter was the most effective, achieving the lowest prevalence (0.7% and 1.7% over the period versus the 3% prevalence in the current situation).

Conclusions

Mathematical modelling that considers the performance of different tests and detection strategies could be a useful tool for decision making. The exploratory results show the efficiency of adopting both the use of the rapid tests and performing active case detection to significantly reduce the burden of syphilis in Chilean prisons in the near future.

Under five and infant mortality in Chile (1990-2016): Trends, disparities, and causes of death

Background

Child health has been a health policy priority for more than a century in Chile. Since 2000, new health and intersectoral interventions have been implemented. However, no recent analyses have explored child mortality and equity in Chile, an indispensable input to guide policies towards the achievement of the Sustainable Development Goals, specially, in the context of a deeply unequal country such as many other Latin American countries. Thus, the objectives of this study are to analyze the variations in the risk and the causes of death among Chilean children aged <5 years, to identify the determinants, and to measure inequality of infant mortality from 1990 to 2016.

Materials and methods

An observational study was conducted to analyze the Chilean children's mortality from 1990 to 2016 using under five deaths and live births data from the Vital Statistics System. To describe the variation in the risk of death, a time series analysis was performed for each of the under five mortality rate components. A comparative cause of death analysis was developed for Neonatal and 1–59 months’ age groups. The determinants of infant mortality were studied with a descriptive analysis of yearly rates according to mother’s and child factors and bivariate logistic regression models at the individual level. Finally, simple and complex measures of inequality at individual level were estimated considering three-year periods.

Results

Regarding under 5 mortality: (i) Child survival has improved substantially in the last three decades, with a rapid decline in under five mortality rate between 1990 and 2001, followed by a slower reduction; (ii) early neonatal mortality has become the main component of the under five mortality rate (50.6%); (iii) congenital abnormalities have positioned as the leading cause of death; (iv) an important increase in live births below 1,000 grs. Regarding infant mortality: (i) birth weight and gestational age are the two most relevant risk factors in the neonatal period, while social variables are more significant for post-neonatal mortality and, (ii) the inequality according to mother’s education has shown a steady decline, with persistent inequalities in post-neonatal period.

Conclusions

The Chilean experience illustrates child health achievements and challenges in a country that transitioned from middle-to high-income in recent decades. Although inequity is one of the main challenges for the country, the health sector by granting universal access was able to reduce disparities. However, closing the gap in post-neonatal mortality is still challenging. To overcome stagnation in neonatal mortality, new and specific strategies must address current priorities, emphasizing the access of vulnerable groups.

Compliance with the smoking ban in urban public transportation in Chile

INTRODUCTION

The aim of the study is to assess the national level of compliance with the Chilean smoke-free legislation in the urban public transportation system.

METHODS

In this cross-sectional observational study, we studied a national representative sample of 475 vehicles obtained through a two-stage cluster sampling design in 2018. First, 57 municipalities were randomly selected, proportionally to the total number of public transportation vehicles. Second, within each municipality, a convenience sample of up to 4 taxis, 4 buses, and 2 metro coaches was observed. We determined the non-compliance level by systematic direct observation of smoking inside the cabin of the vehicle. We estimated the percentage of the visited vehicles where smoking was observed inside the cabin of the vehicle.

RESULTS

The observation of metros, buses and taxis was completed in 24, 52, and 48, of the 57 sampled municipalities, respectively. Smoking was observed inside of about 2% of buses and 7% of taxis. Smoking was not observed in metro carriages. Overall, smoking was observed in almost 3% of the vehicles studied. A 3% noncompliance could expose a significant number of persons in public transportation to secondhand smoke, given that every 100 inhabitants results in about 84 rides a day of almost one hour duration. There are few comparable studies to put in an international context our results. In 2018, the year in which we collected the data, WHO considered that compliance with the law in public transportation was maximum. Our compliance estimate was lower, however WHO used a different methodology and its scope also included the inter-urban mobility, which we did not.

CONCLUSIONS

The study highlights the need to improve the enforcement of the smoke-free law in the transportation system in Chile, which presently is almost non-existent.

Compliance with the smoking ban in enclosed, semiopen and open areas of workplaces and public places in Chile

OBJECTIVE

To assess the national level of compliance with the Chilean comprehensive smoke-free legislation by observing healthcare facilities, education centres, government offices, hospitality venues and private workplaces, by type of area within workplaces and public places: enclosed, semiopen and open.

METHODOLOGY

In this cross-sectional observational study, we studied a national representative sample of 3253 venues obtained through a two-stage cluster sampling design. First, 57 municipalities were randomly selected, proportionally to the total number of venues of interest. Second, within each selected municipality, a maximum of 12 venues of each sector was selected systematically from a list of existing sites. We determined the non-compliance level by estimating the percentage of the visited venues where smoking was observed or suspected in banned areas of the premises.

RESULTS

Smoking or suspicion thereof was not observed in any enclosed area of any establishment. However, smoking violations were observed in semiopen areas ranging from less than 0.5% of schools and healthcare centres to around 10% of hospitality venues or 23.0% of higher education centres. Smoking violations were also observed in outdoor areas of 6.7% and 1.6% of the health centres and schools, respectively.

DISCUSSION

The stark contrast in compliance with the smoking ban between the enclosed areas and the semiopen areas may be a consequence of the complex definition of semiopen areas in the regulations. The study also reflects the need to improve the overall enforcement of the smoke-free law, particularly in universities and hospitality venues.

Evaluation of a novel antigen-based rapid detection test for the diagnosis of SARS-CoV-2 in respiratory samples

•

Due to the rapidly emerging SARS-CoV-2 pandemic and its tremendous public health challenges worldwide, there is a critical demand for rapid and easy to perform diagnostic assays.

•

The rapid antigen detection test evaluated here had a high diagnostic sensitivity and specificity in respiratory samples obtained from patients who mainly presented during the first week of COVID-19.

•

Rapid antigen detection has the potential to become an important tool for the early diagnosis of SARS-CoV-2, particularly in situations with limited access to molecular methods.

Objectives

In the context of the coronavirus disease 2019 (COVID-19) pandemic, the development and validation of rapid and easy-to-perform diagnostic methods are of high priority. This study was performed to evaluate a novel rapid antigen detection test (RDT) for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in respiratory samples.

Methods

The fluorescence immunochromatographic SARS-CoV-2 antigen test (Bioeasy Biotechnology Co., Shenzhen, China) was evaluated using universal transport medium with nasopharyngeal (NP) and oropharyngeal (OP) swabs from suspected COVID-19 cases. Diagnostic accuracy was determined in comparison to SARS-CoV-2 real-time (RT)-PCR.

Results

A total of 127 samples were included; 82 were RT-PCR-positive. The median patient age was 38 years, 53.5% were male, and 93.7% were from the first week after symptom onset. Overall sensitivity and specificity were 93.9% (95% confidence interval 86.5–97.4%) and 100% (95% confidence interval 92.1–100%), respectively, with a diagnostic accuracy of 96.1% and Kappa coefficient of 0.9. Sensitivity was significantly higher in samples with high viral loads.

Conclusions

The RDT evaluated in this study showed a high sensitivity and specificity in samples mainly obtained during the first week of symptoms and with high viral loads, despite the use of a non-validated sample material. The assay has the potential to become an important tool for early diagnosis of SARS-CoV-2, particularly in situations with limited access to molecular methods.

[Worsening situation of tuberculosis in Chile]

BACKGROUND

Recent data suggest an increase in tuberculosis (TB) incidence in Chile.

AIM

To evaluate recent epidemiological trends, geographic extension and potential factors associated with TB reemergence in Chile.

MATERIAL AND METHODS

Data analysis from official sources and trend analysis.

RESULTS

TB incidence rate increased from 12.3 (2014) to 14.7 (2017) per 100,000 inhabitants. Morbidity rates also increased in nine out of 15 regions. The proportion of TB cases in specific groups has also increased in the last six years: HIV/AIDS (68%), immigrants (118%), drug users/alcoholics (267%) and homeless people (370%). Several indicators of the national TB program performance have deteriorated including TB case detection, HIV co-infection study and contact tracing activities. Overall results indicate a higher than expected case-fatality ratio (> 3%), high rates of loss from follow-up (> 5%), and low percentage of cohort healing rate (< 90%). This decline is associated with a Control Program with scarce human resources whose central budget decreased by 90% from 2008 to 2014. New molecular diagnostic tools and liquid media culture were only recently implemented.

CONCLUSIONS

TB trends and overall program performance indicators have deteriorated in recent years in Chile and several factors appear to be involved. Multiple strategies will be required to rectify this situation.

¿Sirven las ayudas técnicas a las personas mayores? Percepción desde la Atención Primaria sobre esta Garantía Explícita en Salud, Santiago, Chile

Objetivo: Conocer la percepción de informantes clave pertenecientes a la red de Atención Primaria de Salud en Chile, respecto al proceso de gestión asistencial y el impacto del programa nacional de Garantías Explícitas en Salud (GES) sobre la entrega de ayudas técnicas a personas mayores. Materiales y métodos: Un estudio cualitativo basado en análisis de casos múltiples, en el cual se realizó entrevistas semi-estructuradas a 8 informantes clave de la red asistencial, fue desarrollado en 2015 en tres comunas de Santiago, Chile. El análisis de la información recogida se realizó mediante análisis de contenido, y se finalizó el muestreo de máxima variación al saturar la información. Se resguardaron los criterios de rigor científico y el protocolo fue aprobado por un Comité de Ética. Resultados: Hay una percepción de cobertura y detección de necesidad como adecuada en pacientes bajo control, aunque desde la perspectiva de los informantes, hay desconocimiento de esta garantía en la población. La necesidad es detectada por cualquier profesional de salud, pero la indicación es exclusivamente médica, lo que genera barreras de acceso. Hay una entrega oportuna; sin embargo, no se realiza seguimiento ni se aprecia como parte de una atención integral. Se percibe que la ayuda técnica es de calidad y la articulación de la red es adecuada, aunque no hay retroalimentación a Atención Primaria de Salud. El impacto lo consideran positivo en pacientes y familiares: mejora la ejecución de actividades diarias y genera mayor autonomía y capacidad de desplazamiento. Conclusiones: Existe una percepción positiva de este programa GES y su impacto en la mejoría en la calidad de vida de vida de los pacientes. Pero, la entrega de ayudas técnicas se encuentra desvinculada de una atención integral, por ende, este programa prioriza sólo la garantía de oportunidad.

Hepatitis B and C virus infection among HIV patients within the public and private healthcare systems in Chile: A cross-sectional serosurvey

BACKGROUND

Coinfections of HIV patients with hepatitis B virus (HBV) and hepatitis C virus (HCV) are mayor public health problems, contributing to the emerging burden of HIV-associated hepatic mortality. Coinfection rates vary geographically, depending on various factors such as predominant transmission modes, HBV vaccination rates, and prevalence of HBV and HCV in the general population. In South America, the epidemiology of coinfections is uncertain, since systematic studies are scarce. Our study aimed to analyze rates of HBV and HCV infection in people living with HIV attending centers of the public and private health system in Chile.

METHODS

We performed a cross-sectional study including a public university hospital and a private health center in Santiago, Metropolitan Region in Chile. Serum samples were used to determine serological markers of hepatitis B (HBsAg, anti-HBs, anti-HBc total, HBeAg, anti-HBe) and anti-HCV. Demographic, clinical and laboratory data were obtained from medical records.

RESULTS

399 patients were included (353 from public, 46 from private health center). Most (92.8%) were male, with a median age of 38.3 years; 99.4% acquired HIV through sexual contact (75.0% MSM); 25.7% had AIDS and 90.4% were on ART. In 78.9%, viral loads were <40 cps/mL; the median CD4 cell count was 468 cells/mm3. According to their serological status, 37.6% of patients were HBV naïve (susceptible), 6.5% were vaccinated, 43.6% had resolved HBV infection, and 5.8% were chronically infected. The rate of vaccination was 4.5% in the public and 21.7% in the private system. HCV coinfection was found in 1.0% of all patients.

CONCLUSION

HBV coinfection rate was within the range of other South American countries, but lower than in non-industrialized regions in Asia and Africa. A low percentage of patients were HBV vaccinated, especially within the public system. HCV coinfection rate was very low, most probably due to the rareness of injecting drug use.

Rare diseases in Chile: challenges and recommendations in universal health coverage context

Rare diseases (RDs) are a large number of diverse conditions with low individual prevalence, but collectively may affect up to 3.5-5.9% of the population. They have psychosocial and economic impact on patients and societies, and are a significant problem for healthcare systems, especially for countries with limited resources. In Chile, financial protection exists for 20 known RDs through different programs that cover diagnosis and treatments. Although beneficial for a number of conditions, most RD patients are left without a proper legal structure that guarantees a financial coverage, and in a vulnerable situation. In this review, we present and analyze the main challenges of the Chilean healthcare system and legislation on RDs, and other ambits of the RD ecosystem, including patient advocacy groups and research. Finally, we propose a set of policy recommendations that includes creating a patient registry, eliciting social preferences on health and financial coverage, improving access to clinical genetic services and therapies, promoting research on RDs and establishing a Latin-American cooperation network, all aimed at promoting equitable quality healthcare access for people living with RDs.

Evaluation of the effectiveness and equity of the maternity protection reform in Chile from 2000 to 2015

INTRODUCTION

According to the International Labor Organization, Maternity Protection (MP) policies try to harmonize child care and women's paid work, without affecting family health and economic security. Chile Law 20.545 (2011) increased benefits for economically active women and reduced requirements for accessing these benefits. The goals of the reform included: 1) to increase MP coverage; and 2) to reduce inequities in access to the benefits.

METHOD

This study uses two data sources. First, using individual data routinely collected from 2000 to 2015, yearly MP coverage access over time was calculated. Second, using national representative household surveys collected before and after the Law (2009 and 2013), coverage and a set of measures of inequality were estimated. To compare changes over time, we used non-experimental, before-after intervention design for independent samples. For each variable, we estimated comparative proportions at 95% confidence interval before and after the intervention. Additionally, we included multivariate and propensity score analysis.

RESULTS

Between 2000 and 2015, MP coverage grew from 24.4% to 44.8%. Using comparable 2009 and 2013 survey data, we observed the same trend, with 31.6% of estimated MP coverage in 2009, escalating to 39.5% in 2013. We conclude that: 1) after the reform, there was an increase in MP coverage; and, 2) there was no significant reduction of inequities in the distribution of MP benefits.

DISCUSSION/CONCLUSION

Few scientific evaluations of MP reforms have been conducted worldwide; even fewer including an equity analysis. This study provides an empirically-based evaluation of MP reform from both a population-level and an equity-focused perspective. We conclude that this reform needs to be complemented with other policies to ensure maternity protection in terms of access and equity in a country with deep socioeconomic stratification.

Assistive Devices for Older Adults: A Longitudinal Study of Policy Effectiveness, Santiago, Chile, 2014-2016

INTRODUCTION Population aging is a worldwide phenomenon. It is estimated that by 2050, one of five persons will be aged ≥60 years. In Chile, 15.8% of the population is now aged ≥60 years, and this figure will reach 30.7% by 2050. In 2006, a national program was implemented to provide assistive devices to older adults aged ≥65 years with limited mobility or difficulty performing activities of daily living. To date, there have been no assessments of the program's effectiveness. OBJECTIVE Assess the effectiveness of an assistive devices policy in Chile on improving functional capacity of older adults aged ≥65 years, and beneficiaries' perceptions of the services received, including changes in their quality of life. METHODS This was a before-after longitudinal study. A cohort of 309 persons was recruited, consisting of patients who received care at a public hospital in Santiago, Chile during 2014-2015. They were assessed before delivery of assistive devices, then followed for seven months, with repeated evaluations made in their homes. The following indicators were measured: functional capacity (Tinetti scale and Barthel Index); changes in perceived quality of life related to use of assistive devices; and other sociodemographic, clinical and protocol-compliance variables. A longitudinal analysis of before-after progress was carried out, as well as a description of service delivery and medical followup. RESULTS Sixty-eight percent of those surveyed were women; median age was 74 years, average schooling was 6 years, and 93% had low income (monthly income <US$398). Assistive devices increased independence in activities of daily living, improved mobility and perceived quality of life, and decreased fall risk and pain. One hundred percent felt satisfied with the service received, 91% were trained in use of the device, and delivery deadlines were met in 83% of cases, but only 2% were followed up. One negative aspect is that the program covers only 25% of estimated need. CONCLUSIONS This assistive device program helps improve functional capacity and perceived quality of life in vulnerable patients who are able to access it. It addresses a real need and is highly valued by patients. Although delivery schedules were fulfilled, followup care schedules were not. KEYWORDS Aging, mobility limitation, assistive devices, activities of daily living, health care system, health care reform, quality of life, Chile.

Case-Control Study of Risk Factors for Meningococcal Disease in Chile

An outbreak of meningococcal disease with a case-fatality rate of 30% and caused by predominantly serogroup W of Neisseria meningitidis began in Chile in 2012. This outbreak required a case−control study to assess determinants and risk factors for infection. We identified confirmed cases during January 2012−March 2013 and selected controls by random sampling of the population, matched for age and sex, resulting in 135 case-patients and 618 controls. Sociodemographic variables, habits, and previous illnesses were studied. Analyses yielded adjusted odds ratios as estimators of the probability of disease development. Results indicated that conditions of social vulnerability, such as low income and overcrowding, as well as familial history of this disease and clinical histories, especially chronic diseases and hospitalization for respiratory conditions, increased the probability of illness. Findings should contribute to direction of intersectoral public policies toward a highly vulnerable social group to enable them to improve their living conditions and health.

Correlates of compliance with national comprehensive smoke-free laws

OBJECTIVE

To explore correlates of high compliance with smoking bans in a cross-sectional data set from the 41 countries with national comprehensive smoke-free laws in 2014 and complete data on compliance and enforcement.

METHODS

Outcome variable: compliance with a national comprehensive smoke-free law in each country was obtained for 2014 from the WHO global report on the global tobacco epidemic. Explanatory variables: legal enforcement requirements, penalties, infrastructure and strategy were obtained through a separate survey of governments. Also, country socioeconomic and demographic characteristics including the level of corruption control were included.

ANALYSIS

an initial bivariate analysis determined the significance of each potentially relevant explanatory variable of high compliance. Differences in compliance were tested using the exact logistic regression.

RESULTS

High compliance with the national comprehensive smoke-free law was associated with the involvement of the local jurisdictions in providing training and/or guidance for inspections (OR=10.3, 95% CI 1.7 to 117.7) and a perception of high corruption control efforts in the country (OR=7.2, 95% CI 1.1 to 85.8).

DISCUSSION

The results show the importance of the depth of the enforcement infrastructure and effort represented by the degree to which the local government is involved in enforcement. They also show the significance of fighting corruption in the enforcement process, including the attempts of the tobacco industry to undermine the process, to achieve high levels of compliance with the law. The results point out to the need to invest minimal but essential enforcement resources given that national comprehensive smoke-free laws are self-enforcing in many but not all countries and sectors.

Knowledge, attitudes, and practices regarding hantavirus disease and acceptance of a vaccine trial in rural communities of southern Chile

Andes hantavirus cardiopulmonary syndrome, transmitted by Oligoryzomys longicaudatus, has no approved treatment, a case fatality rate of 35%, and documented person-to-person transmission. An Andes vaccine, highly needed for prevention, is in development. We aimed to evaluate knowledge, attitudes and practices (KAP) regarding hantavirus disease and willingness to participate in a future Andes vaccine trials through a cross sectional face-to-face oral survey of a randomly selected adult sample from 2 rural communes in southern Chile. Human subjects approval was obtained from our institutional IRBs, and participants signed informed consent. We enrolled 319 subjects from Corral and 321 from Curarrehue; 98% had heard about hantavirus disease and its reservoir but only half knew about transmission, symptoms and prevention. Participants fear the disease but are only partially aware of their own risk. One third of participants reported presence of rodents inside their homes. Despite moderate confidence in their health system, most subjects perceived vaccines as beneficial, and 93% would accept an approved hantavirus vaccine. Half would agree to participate in a vaccine trial and 29% would allow their children to participate. Motivations to participate were mainly altruistic, while risk perception was the main reason for declining. Knowledge about hantavirus disease and prevention practices require reinforcement, and a vaccine trial seems feasible in these populations.

[Clinical features and prognostic factors of meningococcal disease: a case series study in Chile during the 2012-2013 outbreak]

INTRODUCTION

Meningococcal disease (MD) is a major global problem because of its case fatality rate and sequels. Since 2012 cases of serogroup W have increased in Chile, with nonspecific clinical presentation, high case fatality rate and serious consequences.

OBJECTIVE

To characterize the evolution and outcome of MD cases between January 2012 and March 2013 in Chile.

MATERIAL AND METHODS

Case series considering 149 MD cases of 7 regions. A questionnaire was applied and clinical records were reviewed, including individual, agent, clinical course and healthcare process variables. The analysis allowed to obtain estimates of the OR as likelihood of dying.

RESULTS

51.5% was meningococcemia, the case fatality rate reached 27%, prevailing serogroup W (46.6%). Factors that increased the probability of dying: > age, belonging to indigenous people, having lived a stressful event, having diarrhea, impaired consciousness, cardiovascular symptoms, low oxygen saturation and low Glasgow coma scale score.

DISCUSSION

The case fatality rate exceeded normal levels and was higher in serogroup W. Increasing in this serogroup, associated to the increased presence of nonspecific symptoms or rapid progression to septicemia, hit a health system accustomed to more classic meningococcal disease presentation, which could partly explain the observed increased fatality rate.

Topical and intravenous tranexamic acid reduce blood loss compared to routine hemostasis in total knee arthroplasty: a multicenter, randomized, controlled trial

INTRODUCTION

Tranexamic acid (TXA) is becoming widely used in orthopedic surgery to reduce blood loss and transfusion requirements, but consensus is lacking regarding the optimal route and dose of administration. The aim of this study was to compare the efficacy and safety of topical and intravenous routes of TXA with routine hemostasis in patients undergoing primary total knee arthroplasty (TKA).

MATERIALS AND METHODS

We performed a randomized, multicenter, parallel, open-label clinical trial in adult patients undergoing primary TKA. Patients were divided into three groups of 50 patients each: Group 1 received 1 g topical TXA, Group 2 received 2 g intravenous TXA, and Group 3 (control group) had routine hemostasis. The primary outcome was total blood loss. Secondary outcomes were hidden blood loss, blood collected in drains, transfusion rate, number of blood units transfused, adverse events, and mortality.

RESULTS

One hundred and fifty patients were included. Total blood loss was 1021.57 (481.09) mL in Group 1, 817.54 (324.82) mL in Group 2 and 1415.72 (595.11) mL in Group 3 (control group). Differences in total blood loss between the TXA groups and the control group were clinically and statistically significant (p < 0.001). In an exploratory analysis differences between the two TXA groups were not statistically significant (p = 0.073) Seventeen patients were transfused. Transfusion requirements were significantly higher in Group 3 (p = 0.005). No significant differences were found between groups regarding adverse events.

CONCLUSION

We found that 1 g of topical TXA and 2 g of intravenous TXA were both safe strategies and more effective than routine hemostasis to reduce blood loss and transfusion requirements after primary TKA.

LEVEL OF EVIDENCE

I.

Monitoring and evaluating progress towards universal health coverage in Chile

This paper by Ximena Paz Aguilera and colleagues is a country case study for the Universal Health Coverage Collection, organized by WHO. It illustrates progress towards UHC and its monitoring and evaluation in Chile. Please see later in the article for the Editors' Summary

[Barriers and facilitators to antenatal care in adolescents: results of a qualitative study in Chile]

OBJECTIVE

Analyze barriers and facilitators of access to prenatal care in pregnant urban adolescents between 15-19 years of age in Santiago, Chile.

MATERIALS AND METHODS

Qualitative study based on grounded theory with 17 adolescent mothers. Eleven semi-structured interviews and one focus group were conducted.

RESULT

. The denial and concealment of pregnancy is the main barrier to start the prenatal care in the "delayed access group". This group does not identify facilitators. For maintenance in antenatal care, all participants identified a support figure as a facilitator. Family and social vulnerabilities explain why some adolescents start the prenatal care late.

CONCLUSION

The presence of facilitators is crucial for both, the timely entry and the maintenance in antenatal care because they reduce or nullify the effect of barriers. The health system must become a facilitator to accompany adolescents and promote a bond of trust and respect.

Efficacy and safety of fibrin glue and tranexamic acid to prevent postoperative blood loss in total knee arthroplasty: a randomized controlled clinical trial

BACKGROUND

Postoperative blood loss in patients after total knee arthroplasty may cause local and systemic complications and influence clinical outcome. The aim of this study was to assess whether fibrin glue or tranexamic acid reduced blood loss compared with routine hemostasis in patients undergoing total knee arthroplasty.

METHODS

A randomized, single-center, parallel, open clinical trial was performed in adult patients undergoing primary total knee arthroplasty. Patients were divided into four groups. Group 1 received fibrin glue manufactured by the Blood and Tissue Bank of Catalonia, Group 2 received Tissucol (fibrinogen and thrombin), Group 3 received intravenous tranexamic acid, and Group 4 (control) had no treatment other than routine hemostasis. The primary outcome was total blood loss collected in drains after surgery. Secondary outcomes were the calculated hidden blood loss, transfusion rate, preoperative and postoperative hemoglobin, number of blood units transfused, adverse events, and mortality.

RESULTS

One hundred and seventy-two patients were included. The mean total blood loss (and standard deviation) collected in drains was 553.9 ± 321.5 mL for Group 1, 567.8 ± 299.3 mL for Group 2, 244.1 ± 223.4 mL for Group 3, and 563.5 ± 269.7 mL for Group 4. In comparison with the control group, Group 3 had significantly lower total blood loss (p < 0.001), but it was not significantly lower in Groups 1 and 2. The overall rate of patients who had a blood transfusion was 21.1% (thirty-five of 166 patients analyzed per protocol). Two patients required transfusion in Group 3 compared with twelve patients in Group 4 (p = 0.015). No significant difference was observed between the two fibrin glue groups and the control group with regard to the need for transfusion. There was no difference between groups with regard to the percentage of adverse events.

CONCLUSIONS

Neither type of fibrin glue was more effective than routine hemostasis in reducing postoperative bleeding and transfusion requirements, and we no longer use them. However, this trial supports findings from previous studies showing that intravenous tranexamic acid can decrease postoperative blood loss.

Barreras y facilitadores para el control prenatal en adolescentes: resultados de un estudio cualitativo en Chile

Objetivo. Analizar barreras y facilitadores de acceso a control prenatal en adolescentes urbanas de 15-19 años en Santiago, Chile. Material y métodos. Estudio cualitativo con 17 madres adolescentes basado en la teoría fundamentada. Se realizaron 11 entrevistas semiestructuradas y un grupo focal. Resultados. La negación y ocultamiento del embarazo es la principal barrera para ingresar a control en el grupo de acceso tardío; no se identificaron facilitadores. Para mantenerse en control, todas las participantes identifican como facilitador contar con una figura de apoyo. La vulnerabilidad familiar y social explica que algunas adolescentes ingresen a control tardíamente. Conclusión. La presencia de facilitadores es determinante para el ingreso oportuno y mantenerse en control, ya que reduce o anula el efecto de las barreras. El sistema de salud debe constituirse en un facilitador que acompañe desde muy temprano a las adolescentes favoreciendo un vínculo de confianza y respeto.

The basic reproduction number R0 and effectiveness of reactive interventions during dengue epidemics: the 2002 dengue outbreak in Easter Island, Chile

We use a stochastic simulation model to explore the effect of reactive intervention strategies during the 2002 dengue outbreak in the small population of Easter Island, Chile. We quantified the effect of interventions on the transmission dynamics and epidemic size as a function of the simulated control intensity levels and the timing of initiation of control interventions. Because no dengue outbreaks had been reported prior to 2002 in Easter Island, the 2002 epidemic provided a unique opportunity to estimate the basic reproduction number R0 during the initial epidemic phase, prior to the start of control interventions. We estimated R0 at 27.2 (95%CI: 14.8, 49.3). We found that the final epidemic size is highly sensitive to the timing of start of interventions. However, even when the control interventions start several weeks after the epidemic onset, reactive intervention efforts can have a significant impact on the final epidemic size. Our results indicate that the rapid implementation of control interventions can have a significant effect in reducing the epidemic size of dengue epidemics.

Addressing the public health burden of respiratory viruses: the Battle against Respiratory Viruses (BRaVe) Initiative

Given the enormous estimated burden of respiratory virus infections worldwide, a substantial number of research priorities exist in order to better understand their epidemiology, pathogenesis, prevention and clinical management across different populations and resource settings. New therapeutics and specific vaccines for noninfluenza respiratory virus infections could provide enormous benefits in reducing the morbidity and mortality associated with these frequent infections and provide the foundation for responding to newly emerging threats. The BRaVe Initiative is a new WHO-led effort to catalyze multidisciplinary research on strategies to prevent and treat medically important respiratory virus infections with the goal of timely integration of scientific advances and technical innovations into public health practice.

Tropical high-altitude Andean lakes located above the tree line attenuate UV-A radiation more strongly than typical temperate alpine lakes

Tropical high-altitude Andean lakes are physically harsh ecosystems. Located above the treeline (≥4000 m a.s.l.), they share common features with temperate alpine lakes, which impose extreme conditions on their aquatic organisms: e.g., strong winds, broad diel variations in water temperature, and intense solar ultraviolet radiation (UVR). However, because of their latitude, they differ in two major ecological characteristics: they lack ice cover during the winter and they do not present summer water column stratification. We sampled 26 tropical high-altitude Andean lakes from three regions of the Bolivian Eastern Andes Cordillera during the wet period (austral summer). We performed an ordination to better describe the typology of Andean lakes in relation to the environmental variables, and we assessed the relationships among them, focussing on the UV-A transparency (360 nm) throughout the water column. We found a positive correlation between UV-A transparency calculated as Z(1%) (the depth which reaches 1% of the surface UV-A), the lake maximum depth and Secchi transparency (r = 0.61). Z(1%) of UV-A was smaller in shallow lakes than in deep lakes, indicating that shallow lakes are less transparent to UV-A than deep lakes. We hypothesize that, compared to shallow lakes, deep lakes (maximum depth > 10 m) may have lower dissolved organic carbon (DOC) concentrations (that absorb UV radiation) due to lower temperature and reduced macrophyte cover. Based on our data, tropical high-altitude Andean lakes are less transparent to UV-A (K(d) range = 1.4-11.0 m(-1); Z(1%) depth range = 0.4-3.2 m) than typical temperate alpine lakes (1-6 m(-1), 3-45 m, respectively). Moreover, they differ in vertical profiles of UV-A, chlorophyll-a, and temperature, suggesting that they may have a distinct ecological functioning. Such peculiarities justify treating tropical high-altitude Andean lakes as a separate category of alpine lakes. Tropical high-altitude Andean lakes have been poorly studied. Thus they deserve more in-depth studies in the face of global changes regarding the use of their UV transparency as a sentinel proxy of climate changes, particularly global warming.

Major cardiovascular risk factors in Latin America: a comparison with the United States. The Latin American Consortium of Studies in Obesity (LASO)

BACKGROUND

Limited knowledge on the prevalence and distribution of risk factors impairs the planning and implementation of cardiovascular prevention programs in the Latin American and Caribbean (LAC) region.

METHODS AND FINDINGS

Prevalence of hypertension, diabetes mellitus, abnormal lipoprotein levels, obesity, and smoking were estimated from individual-level patient data pooled from population-based surveys (1998-2007, n=31,009) from eight LAC countries and from a national survey of the United States (US) population (1999-2004) Age and gender specific prevalence were estimated and age-gender adjusted comparisons between both populations were conducted. Prevalence of diabetes mellitus, hypertension, and low high-density lipoprotein (HDL)-cholesterol in LAC were 5% (95% confidence interval [95% CI]: 3.4, 7.9), 20.2% (95% CI: 12.5, 31), and 53.3% (95% CI: 47, 63.4), respectively. Compared to LAC region's average, the prevalence of each risk factor tended to be lower in Peru and higher in Chile. LAC women had higher prevalence of obesity and low HDL-cholesterol than men. Obesity, hypercholesterolemia, and hypertriglyceridemia were more prevalent in the US population than in LAC population (31 vs. 16.1%, 16.8 vs. 8.9%, and 36.2 vs. 26.5%, respectively). However, the prevalence of low HDL-cholesterol was higher in LAC than in the US (53.3 vs. 33.7%).

CONCLUSIONS

Major cardiovascular risk factors are highly prevalent in LAC region, in particular low HDL-cholesterol. In addition, marked differences do exist in this prevalence profile between LAC and the US. The observed patterns of obesity-related risk factors and their current and future impact on the burden of cardiovascular diseases remain to be explained.

H1N1pdm in the Americas

In late April 2009 the emergence of 2009 pandemic influenza A (H1N1pdm) virus was detected in humans. From its detection through July 18th, 2009, confirmed cases of H1N1pdm in the Americas were periodically reported to the Pan American Health Organization (PAHO) by member states. Because the Americas span much of the world's latitudes, this data provides an excellent opportunity to examine variation in H1N1pdm transmission by season. Using reports from PAHO member states from April 26th, 2009 through July 18th, 2009, we characterize the early spread of the H1N1 pandemic in the Americas. For a geographically representative sample of member states we estimate the reproductive number (R) of H1N1pdm over the reporting period. The association between these estimates and latitude, temperature, humidity and population age structure was estimated. Estimates of the peak reproductive number of H1N1pdm ranged from 1.3 (for Panama, Colombia) to 2.1 (for Chile). We found that reproductive number estimates were most associated with latitude in both univariate and multivariate analyses. To the extent that latitude is a proxy for seasonal changes in climate and behavior, this association suggests a strong seasonal component to H1N1pdm transmission. However, the reasons for this seasonality remain unclear.

Global health security and the International Health Regulations

Global nuclear proliferation, bioterrorism, and emerging infections have challenged national capacities to achieve and maintain global security. Over the last century, emerging infectious disease threats resulted in the development of the preliminary versions of the International Health Regulations (IHR) of the World Health Organization (WHO). The current HR(2005) contain major differences compared to earlier versions, including: substantial shifts from containment at the border to containment at the source of the event; shifts from a rather small disease list (smallpox, plague, cholera, and yellow fever) required to be reported, to all public health threats; and shifts from preset measures to tailored responses with more flexibility to deal with the local situations on the ground. The new IHR(2005) call for accountability. They also call for strengthened national capacity for surveillance and control; prevention, alert, and response to international public health emergencies beyond the traditional short list of required reporting; global partnership and collaboration; and human rights, obligations, accountability, and procedures of monitoring. Under these evolved regulations, as well as other measures, such as the Revolving Fund for vaccine procurement of the Pan American Health Organization (PAHO), global health security could be maintained in the response to urban yellow fever in Paraguay in 2008 and the influenza (H1N1) pandemic of 2009-2010.

Surveillance system for infectious diseases of pets, Santiago, Chile

Pet diseases may pose risks to human health but are rarely included in surveillance systems. A pilot surveillance system of pet infectious diseases in Santiago, Chile, found that 4 canine and 3 feline diseases accounted for 90.1% and 98.4% of notifications, respectively. Data also suggested association between poverty and pet diseases.

Distribution patterns, population status and conservation of Melanosuchus niger and Caiman yacare (Crocodylia, Alligatoridae) in oxbow lakes of the Ichilo river floodplain, Bolivia

Caiman yacare (lagarto) and Melanosuchus niger (black caiman), sympatric species in the Bolivian Amazon basin, have been severely overexploited in the past. We present the results of a standardized survey of C. yacare and M. niger populations in order to evaluate their actual population status in twelve oxbow lakes of the Ichilo River floodplain. Additionally we explored the effect of environmental and anthropogenic variables on caiman distribution patterns. The average density of C yacare and M niger in the shoreline of floodplain lakes was of 6 and 1 ind/km, respectively. For both species, the population was composed mainly of juvenile individuals. We used regression tree analysis (RTA) to assess patterns of M. niger and C. yacare densities with eight environmental and two anthropogenic variables. The RTA analysis showed that the variation in the densities of both C. yacare (52.4%) and M. niger (36.8 %) was related to water conductivity. For C yacare, higher densities occurred at higher values of water conductivity, while M. niger densities followed an opposite trend, resulting in relatively well spatially segregated populations of the two species. After excluding conductivity, Lake-River Distance (LRD) was shown to be the main splitting variable in the RTA analysis. The observed distribution patterns may be the result of the historical post-hunting situation, in combination with differences in habitat selection by the two species, and competitive exclusion processes between the two species. M. niger, a species reported to be recovering slowly from previous low population levels, appears relatively well protected in the Ichilo river floodplain.

The Latin American Consortium of Studies in Obesity (LASO)

Current, high-quality data are needed to evaluate the health impact of the epidemic of obesity in Latin America. The Latin American Consortium of Studies of Obesity (LASO) has been established, with the objectives of (i) Accurately estimating the prevalence of obesity and its distribution by sociodemographic characteristics; (ii) Identifying ethnic, socioeconomic and behavioural determinants of obesity; (iii) Estimating the association between various anthropometric indicators or obesity and major cardiovascular risk factors and (iv) Quantifying the validity of standard definitions of the various indexes of obesity in Latin American population. To achieve these objectives, LASO makes use of individual data from existing studies. To date, the LASO consortium includes data from 11 studies from eight countries (Argentina, Chile, Colombia, Costa Rica, Dominican Republic, Peru, Puerto Rico and Venezuela), including a total of 32,462 subjects. This article describes the overall organization of LASO, the individual studies involved and the overall strategy for data analysis. LASO will foster the development of collaborative obesity research among Latin American investigators. More important, results from LASO will be instrumental to inform health policies aiming to curtail the epidemic of obesity in the region.

Interethnic differences in the accuracy of anthropometric indicators of obesity in screening for high risk of coronary heart disease

BACKGROUND

Cut points for defining obesity have been derived from mortality data among Whites from Europe and the United States and their accuracy to screen for high risk of coronary heart disease (CHD) in other ethnic groups has been questioned.

OBJECTIVE

To compare the accuracy and to define ethnic and gender-specific optimal cut points for body mass index (BMI), waist circumference (WC) and waist-to-hip ratio (WHR) when they are used in screening for high risk of CHD in the Latin-American and the US populations.

METHODS

We estimated the accuracy and optimal cut points for BMI, WC and WHR to screen for CHD risk in Latin Americans (n=18 976), non-Hispanic Whites (Whites; n=8956), non-Hispanic Blacks (Blacks; n=5205) and Hispanics (n=5803). High risk of CHD was defined as a 10-year risk > or =20% (Framingham equation). The area under the receiver operator characteristic curve (AUC) and the misclassification-cost term were used to assess accuracy and to identify optimal cut points.

RESULTS

WHR had the highest AUC in all ethnic groups (from 0.75 to 0.82) and BMI had the lowest (from 0.50 to 0.59). Optimal cut point for BMI was similar across ethnic/gender groups (27 kg/m(2)). In women, cut points for WC (94 cm) and WHR (0.91) were consistent by ethnicity. In men, cut points for WC and WHR varied significantly with ethnicity: from 91 cm in Latin Americans to 102 cm in Whites, and from 0.94 in Latin Americans to 0.99 in Hispanics, respectively.

CONCLUSION

WHR is the most accurate anthropometric indicator to screen for high risk of CHD, whereas BMI is almost uninformative. The same BMI cut point should be used in all men and women. Unique cut points for WC and WHR should be used in all women, but ethnic-specific cut points seem warranted among men.