Laura Andrea Rodríguez-Villamizar

Epidemiology, risk factors and genotypes of HBV in HIV-infected patients in the northeast region of Colombia: high prevalence of occult hepatitis B and F3 subgenotype dominance.

Introduction Chronic hepatitis B virus (HBV) infection is an increasing cause of morbidity and mortality in human immunodeficiency virus (HIV)-infected individuals. HIV-positive patients are commonly co-infected with HBV due to shared routes of transmission. Objectives Our aim was to determine the risk factors, prevalence, genotypes, and mutations of the Surface S gene of HBV, and occult hepatitis B infection (OBI) among patients infected with HIV in a northeastern Colombian city. Methods A cross-sectional study was conducted with 275 HIV-positive patients attending an outpatient clinic in Bucaramanga, Colombia during 2009–2010. Blood samples were collected and screened for serological markers of HBV (anti-HBs, anti-HBc and HBsAg) through ELISA assay. Regardless of their serological profile, all samples were tested for the HBV S gene by nested-PCR and HBV genotypes were determined by phylogenetic inference. Clinical records were used to examine demographic, clinical, virological, immunological and antiretroviral therapy (ART) variables of HIV infection. Results Participants were on average 37±11 years old and 65.1% male. The prevalence of HIV-HBV coinfection was 12% (95%CI 8.4–16.4) of which 3.3% had active HBV infection and 8.7% OBI. The prevalence of HIV-HBV coinfection was associated with AIDS stage and ART treatment. Sequence analysis identified genotype F, subgenotype F3 in 93.8% of patients and genotype A in 6.2% of patients. A C149R mutation, which may have resulted from failure in HBsAg detection, was found in one patient with OBI. Conclusions The present study found a high prevalence of HIV-HBV coinfection with an incidence of OBI 2.6-fold higher compared to active HBV infection. These findings suggest including HBV DNA testing to detect OBI in addition to screening for HBV serological markers in HIV patients.

The Effects of Outdoor Air Pollution on the Respiratory Health of Canadian Children: A Systematic Review of Epidemiological Studies

BACKGROUND Outdoor air pollution is a global problem with serious effects on human health, and children are considered to be highly susceptible to the effects of air pollution. OBJECTIVE To conduct a comprehensive and updated systematic review of the literature reporting the effects of outdoor air pollution on the respiratory health of children in Canada. METHODS Searches of four electronic databases between January 2004 and November 2014 were conducted to identify epidemiological studies evaluating the effect of exposure to outdoor air pollutants on respiratory symptoms, lung function measurements and the use of health services due to respiratory conditions in Canadian children. The selection process and quality assessment, using the Newcastle-Ottawa Scale, were conducted independently by two reviewers. RESULTS Twenty-seven studies that were heterogeneous with regard to study design, population, respiratory outcome and air pollution exposure were identified. Overall, the included studies reported adverse effects of outdoor air pollution at concentrations that were below Canadian and United States standards. Heterogeneous effects of air pollutants were reported according to city, sex, socioeconomic status and seasonality. The present review also describes trends in research related to the effect of air pollution on Canadian children over the past 25 years. CONCLUSION The present study reconfirms the adverse effects of outdoor air pollution on the respiratory health of children in Canada. It will help researchers, clinicians and environmental health authorities identify the available evidence of the adverse effect of outdoor air pollution, research gaps and the limitations for further research.

Human mercury exposure and irregular menstrual cycles in relation to artisanal gold mining in Colombia

INTRODUCTION Artisanal mining commonly extracts gold with an amalgamation process that uses mercury. The reproductive effects from exposure to elemental mercury used in gold mining have not been sufficiently studied. OBJECTIVE To evaluate the effect of the exposure to elemental mercury used in gold mining on menstrual cycle regularity and the occurrence of miscarriages in Colombia. MATERIALS AND METHODS An analytical cross-sectional study was conducted. The participants were female residents of gold mining districts, with a history of exposure to elemental mercury. Menstrual regularity and the occurrence of miscarriages were compared between these women and an unexposed group. Exposure and outcome variables were registered based on a questionnaire which was evaluated for its test-retest reproducibility. Prevalence rates were calculated using a binomial model and goodness-of-fit was evaluated. RESULTS A total of 72 women exposed to mercury and 121 unexposed women participated. The average time of exposure to mercury among exposed women was 19.58 ± 9.53 years. The adjusted prevalence of irregular menstruation over the last six months was higher in the group of women chronically exposed to mercury vapors (PR=1.59, 95% CI 0.93-2.73), while there was no difference in the proportion of women with a history of miscarriages. CONCLUSIONS Exposure to elemental mercury used in artisanal gold mining may be associated with a higher prevalence of irregular menstrual cycles but not with the occurrence of miscarriage.

The effects of air pollution on respiratory health in susceptible populations: a multilevel study in Bucaramanga, Colombia

We conducted a cohort study to investigate the association between exposure to three different levels of outdoor air pollution and incidence of respiratory symptoms in a population with chronic cardiovascular and respiratory disease. We accompanied 756 participants for a period of six months through the maintenance of a daily record of symptoms and clinic visits. The symptoms with highest incidence rates were sneezing and hacking cough. Multivariate analysis showed that incidence of total symptoms was 60% and 74% lower in areas with medium and low levels of pollution compared to areas with high levels of pollution. These results suggest that negative respiratory effects occur at concentrations of particulate matter PM10 > 60 ug/m(3).

The role of socioeconomic position as an effect-modifier of the association between outdoor air pollution and children's asthma exacerbations: an equity-focused systematic review.

Abstract Background: The role of socioeconomic position (SEP) as an effect modifier of the association between asthma exacerbations and outdoor air pollution remains unclear. Objective: To identify and summarize the evidence regarding SEP as an effect modifier of the association between asthma exacerbations and outdoor air pollution in children. Methods: We conducted searches in five electronic databases from January 1950 to June 2015 with no language restriction. Observational studies involving children, measuring any non-biological outdoor air pollutant exposure, resulting in any asthma-related health service use, and reporting measures of effect by individual or aggregated SEP measures were included. Results: Ten studies met the inclusion criteria. Five studies reported on hospitalizations, three on emergency department visits, one on ambulatory visits, and one on repeat hospital visits. Six studies identified differential effects of the effect of air pollution on asthma outcomes by SEP with stronger effects for children with a low SEP level; however, the analysis of interaction between air pollutants and SEP was significant in one study of asthma hospitalizations only. The differential effect was reported using individual and aggregated SEP measures. Conclusion: This review reveals that there is weak evidence of SEP as an effect-modifier of the association between air pollution and children’s asthma exacerbations. While stronger negative effects on asthma-related hospitalizations occur for children living in a lower SEP, the sample size of some of the original studies limited the statistical assessment of the modification effect.

Lack of autoantibody induction by mercury exposure in artisanal gold mining settings in Colombia: Findings and a review of the epidemiology literature

Abstract Mercury (Hg) has been implicated as an immunotoxicant in experimental animal models, but its role in the induction of human autoimmunity remains unclear due to contradictory findings. Therefore, it has been claimed that it is important to examine other populations in order to clarify the role of Hg in these diseases. The aim of this study was to investigate whether occupational Hg exposure due to artisanal gold mining is associated with the prevalence of autoimmune biomarkers. A cross-sectional study was conducted comparing Hg-exposed gold miners (n = 164) with a control population (n = 127). Hair, blood, and 24-h urine samples were collected for measures of Hg levels, as well as of anti-nuclear antibodies (ANA) and rheumatoid factor (RF). Participants were clinically evaluated by a general practice physician, a rheumatologist, and a toxicologist. Statistically significant differences (p < 0.001) were found between Hg-exposed and non-exposed groups for all Hg biomarkers tested: blood (7.03 versus 2.46 µg Hg/L), urine (3.96 versus 1.48 µg Hg/g creatinine), and hair (0.79 versus 0.39 µg Hg/g). No difference was observed in ANA (cut-off titre of 1:80; PR = 0.93, 95% CI = 0.45–1.90) and RF (cut-off = 30 IU/mL; PR = 0.062, 95% CI = 0.03–1.08) status between the groups. In conclusion, the findings here do not support the hypothesis that Hg exposure due to artisanal gold mining activities had a significant impact on autoantibodies as biomarkers of autoimmune diseases. In a review context, the epidemiological findings were interpreted in light of the conflicting data in the literature about how Hg exposure was linked to development of autoantibodies. Validation of these findings in prospective studies is needed to firmly establish the role of Hg in development of autoimmunity in human populations.

Weather and Suicide: A Decade Analysis in the Five Largest Capital Cities of Colombia

Historically, seasonal variations in suicide rates were thought to be associated with changes in weather. Most of this evidence however, is based on studies that were conducted in developed countries that are located outside the tropics. As such, it is necessary to examine this association in developing countries, such as Colombia, which do not experience marked seasons. In addition, it is important to adjust for the effect of holidays when analyzing this association as they have been reported to be a relevant confounding factor. Our objective was to estimate the association between daily suicide incidence among men and women in five major Colombian cities (Bogotá, Medellin, Cali, Barranquilla, and Bucaramanga) and daily temperature and rainfall. For this purpose, we conducted a multi-city, multi-temporal ecological study from 2005 to 2015, using data from the suicide mortality registries (provided by the National Administrative Department of Statistics). Daily measurements of the two weather variables were obtained from the official historical registry of the meteorological station at each city airport. We used these data to estimate conditional Poisson models for daily suicide counts, stratifying by sex and adjusting for holidays. Although we found that none of the weather variable estimators could reject the null hypothesis, we uncovered an association between suicide incidence and long weekends in the total suicide model (Incidence Rate Ratio (IRR): 1.19, 95% confidence interval (CI): 1.04–1.23). We found no evidence of association between weather variables and suicide in Colombia. Our study is based on daily observations and it provides evidence of absence of this association in a tropical country that does not experience marked seasons.

Inferencia causal en epidemiología

This essay makes a brief account of the historical development of epidemiology as a fundamental element for understanding the development of thought and causality models. Subsequently, the theoretical foundations that support the identification of causal relationships and the available models and methods of analysis are exposed, providing some examples of their application. Finally, the strengths and limitations of this epidemiological analysis during the identification of causal relationships are presented.

Environmental and occupational health research and training needs in Colombia: A Delphi study

INTRODUCTION Environmental factors contribute with 16% of the burden of disease in Colombia. A main obstacle in implementing national and regional environmental and occupational health policies is the limited knowledge on the local ability to study and control the impact of harmful exposures on health. OBJECTIVE To identify needs for research and training in environmental and occupational health in Colombia. MATERIALS AND METHODS We conducted a three-round hybrid Delphi study. A group of environmental and occupational health Colombian experts (n=16) from government agencies, universities, and research centers was recruited to participate in the study. Expert´s opinions on research and training needs were gathered through online questionnaires, followed by an in-person meeting. The percentage of agreement and the coefficient of variation were used to measure consensus. RESULTS Air pollution and chemical products were considered the most important environmental and occupational exposures, due to their significant impact on chronic non-communicable diseases, such as respiratory diseases, cardiovascular diseases, and cancer. Research on the effects of outdoor air pollution on cardiovascular and respiratory diseases was considered of the greatest importance. Priority training areas included environmental and occupational health risk assessment, exposure modeling, advanced statistical methods, urban planning, occupational safety and hygiene, and epidemiology and toxicology. CONCLUSIONS These findings provide a valuable input for the definition and implementation of national environmental and occupational health policies and for the development of a regional hub aimed at strengthening the capacity for research and training in Colombia.

Short-Term Effects of Air Pollution on Respiratory and Circulatory Morbidity in Colombia 2011–2014: A Multi-City, Time-Series Analysis

Few studies have been conducted on the effect of air pollution on morbidity in Latin America. This study analyzed the effects of air pollution on respiratory and circulatory morbidity in four major cities in Colombia. An ecological time-series analysis was conducted with pollution data from air quality monitoring networks and information on emergency department visits between 2011 and 2014. Daily 24-h averages were calculated for NO2, PM10, PM2.5, and SO2 as well as 8-h averages for CO and O3. Separate time-series were constructed by disease group and pollutant. Conditional negative binomial regression models were used with average population effects. Effects were calculated for the same day and were adjusted for weather conditions, age groups, and their interactions. The results showed that effects of some of the pollutants differed among the cities. For NO2, PM10, and PM2.5, the multi-city models showed greater and statistically significant percentage increases in emergency department visits for respiratory diseases, particularly for the 5 to 9-year-old age group. These same pollutants also significantly affected the rate of emergency department visits for circulatory diseases, especially for the group of persons over 60 years of age.