Asthma in Latin America: a public heath challenge and research opportunity

Lifestyle domains as determinants of wheeze prevalence in urban and rural schoolchildren in Ecuador: cross sectional analysis

BACKGROUND

The acquisition of a modern lifestyle may explain variations in asthma prevalence between urban and rural areas in developing countries. However, the effects of lifestyle on asthma have been investigated as individual factors with little consideration given to the effects of lifestyle as a set of attributes. The aim of the present study was to identify modern lifestyle domains and assess how these domains might explain wheeze prevalence in urban and rural areas.

METHODS

We analysed data from cross-sectional studies of urban and rural schoolchildren in Esmeraldas Province, Ecuador. Variables were grouped as indicators of socioeconomic factors, sedentarism, agricultural activities and household characteristics to represent the main lifestyle features of the study population. We used multiple correspondence analyses to identify common lifestyle domains and cluster analysis to allocate children to each domain. We evaluated associations between domains and recent wheeze by logistic regression.

RESULTS

We identified 2-3 lifestyle domains for each variable group. Although wheeze prevalence was similar in urban (9.4%) and rural (10.3%) schoolchildren, lifestyle domains presented clear associations with wheeze prevalence. Domains relating to home infrastructure (termed transitional, rudimentary, and basic urban) had the strongest overall effect on wheeze prevalence in both urban (rudimentary vs. basic urban, OR = 2.38, 95% CI 1.12-5.05, p = 0.024) and rural areas (transitional vs. basic urban, OR = 2.02, 95% CI 1.1-3.73, p = 0.024; rudimentary vs. basic urban, OR = 1.88, 95% CI 1.02-3.47, p = 0.043). A high level of sedentarism was associated with wheeze in the rural areas only (OR = 1.64, 95% CI 1.23-2.18, p = 0.001).

CONCLUSIONS

We identified lifestyle domains associated with wheeze prevalence, particularly living in substandard housing and a high level of sedentarism. Such factors could be modified through programmes of improved housing and education. The use of lifestyle domains provides an alternative methodology for the evaluation of variations in wheeze prevalence in populations with different levels of development.

Social determinants of childhood asthma symptoms: an ecological study in urban Latin America

Asthma is an important public health problem in urban Latin America. This study aimed to analyze the role of socioeconomic and environmental factors as potential determinants of asthma symptoms prevalence in children from Latin American (LA) urban centers. We selected 31 LA urban centers with complete data, and an ecological analysis was performed. According to our theoretical framework, the explanatory variables were classified in three levels: distal, intermediate, and proximate. The association between variables in the three levels and prevalence of asthma symptoms was examined by bivariate and multivariate linear regression analysis weighed by sample size. In a second stage, we fitted several linear regression models introducing sequentially the variables according to the predefined hierarchy. In the final hierarchical model Gini Index, crowding, sanitation, variation in infant mortality rates and homicide rates, explained great part of the variance in asthma prevalence between centers (R(2) = 75.0 %). We found a strong association between socioeconomic and environmental variables and prevalence of asthma symptoms in LA urban children, and according to our hierarchical framework and the results found we suggest that social inequalities (measured by the Gini Index) is a central determinant to explain high prevalence of asthma in LA.

Association between eating patterns and body mass index in a sample of children and adolescents in Northeastern Brazil

The aim of this study was to assess the relationship between eating patterns and body mass index (BMI) in children and adolescents. This is a cross-sectional study of 1,247 male and female students, aged between 6 and 12, from public elementary schools in São Francisco do Conde, Bahia State, Brasil. BMI was used to analyze the children’s nutritional status. Food consumption frequencies, in addition to demographic and socioeconomic information, were collected for each participant. Dietary patterns were identified through a factor analysis. The prevalence of overweight and obesity was 17.3% (10.2% overweight and 7.1% obese). Two eating patterns, “obesogenic” and “prudent”, were identified. The former is characterized by sweets and sugars, typical Brazilian dishes, pastries, fast food, oils, milk, cereals, cakes, and sauces, and was positively associated with increased BMI (ßi = 0.244; p = 0.018). An “obesogenic” dietary pattern was associated with increased BMI.

The prevalence of wheezing and its association with serum zinc concentration in children and adolescents in Brazil

OBJECTIVE

To assess the influence of zinc serum status on the prevalence of wheezing in a sample of children and adolescents in Northeastern Brazil.

RESEARCH METHODS AND PROCEDURES

This is a cross-sectional study which included 592 students of 6-12 years old, from the public elementary schools of São Francisco do Conde, Bahia, Northeastern Brazil. Report of wheezing in the past 12 months was collected using a questionnaire of the International Study of Asthma and Allergies in Childhood Program (ISAAC) phase III, adapted to Portuguese. The determination of serum Zn levels was performed using a flame atomic absorption spectrometer. Data on anthropometric status, level of physical activity, pubertal development and socioeconomic information, for each participant were obtained. Multivariate logistic regression analyses were used to assess the associations of interest.

RESULTS

Of the students, 8.6% (95% CI 6.30-10.9) reported having wheezing. The mean (SD) serum zinc level was 114 (22.9 μg/dL). The results of the multiple logistic regression analysis showed, after adjustments, positive and significant association between low serum zinc levels and wheezing. Students categorized as being below the median for serum Zn concentration presented an almost 1.9-fold increase in the wheezing prevalence ratio (OR=1.9; 95% CI 1.03-3.53).

CONCLUSION

The main findings of this study suggest that the level of zinc may influence the risk of wheezing in late childhood on the study population.

Risk factors for non-atopic asthma/wheeze in children and adolescents: a systematic review

Background

The study of non-atopic asthma/wheeze in children separately from atopic asthma is relatively recent. Studies have focused on single risk factors and had inconsistent findings.

Objective

To review evidence on factors associated with non-atopic asthma/wheeze in children and adolescents.

Methods

A review of studies of risk factors for non-atopic asthma/wheeze which had a non-asthmatic comparison group, and assessed atopy by skin-prick test or allergen-specific IgE.

Results

Studies of non-atopic asthma/wheeze used a wide diversity of definitions of asthma/wheeze, comparison groups and methods to assess atopy. Among 30 risk factors evaluated in the 43 studies only 3 (family history of asthma/rhinitis/eczema, dampness/mold in the household, and lower respiratory tract infections in childhood) showed consistent associations with non-atopic asthma/wheeze. No or limited period of breastfeeding was less consistently associated with non-atopic asthma/wheeze. The few studies examining the effects of overweight/obesity and psychological/social factors showed consistent associations. We used a novel graphical presentation of different risk factors for non-atopic asthma/wheeze, allowing a more complete perception of the complex pattern of effects.

Conclusions

More research using standardized methodology is needed on the causes of non-atopic asthma.

Food and nutrition insecurity: a marker of vulnerability to asthma symptoms

OBJECTIVE

To evaluate the association between food and nutrition insecurity and asthma in children from Latin America.

DESIGN

Cross-sectional study.

SETTING

São Francisco do Conde, Bahia, north-eastern Brazil.

SUBJECTS

The study included 1307 children aged 6-12 years from public elementary schools. Asthma symptoms were collected using a questionnaire that was translated and adapted from the International Study of Asthma and Allergies in Childhood, phase III. The diagnosis of asthma was determined based on reports of wheezing in the previous 12 months. The Brazilian Food Insecurity Scale was used to identify food insecurity. We also obtained demographic, socio-economic and anthropometric information for each participant. We used multivariate logistic regression analyses to assess the associations of interest.

RESULTS

Of the children surveyed, 10·4% had a history of wheezing and 64·5% had some degree of food and nutrition insecurity. We found a positive dose-response relationship and statistically significant associations of asthma with moderate (OR = 1·71, 95% CI 1·01, 2·89) and severe (OR = 2·51, 95% CI 1·28, 4·93) food and nutrition insecurity.

CONCLUSIONS

The results show that moderate and severe food and nutrition insecurity are markers of vulnerability to wheezing. It is important to note that the results of studies in this field have potential implications for social policies that promote food security. Further studies to identify the mechanisms involved in the relationship between food and nutrition insecurity and asthma are needed.

Prevalence and severity of asthma and related symptoms in 6- to 7-year-old schoolchildren of Rio de Janeiro using of the ISAAC questionnaire by telephone survey

OBJECTIVE

To evaluate the prevalence and severity of asthma and its association with sex in 6- to 7-year-old schoolchildren from the city of Rio de Janeiro (RJ), obtained by a telephone survey.

METHODS

A cross-sectional study using the International Study of Asthma and Allergies in Childhood (ISAAC) Written Questionnaire for Asthma adapted and validated by telephone interviews was conducted. The random sample was recruited systematically, without replacement, taking into account the proportion of school classes and students in each regional coordination of the Municipal Secretariat of Education, which supplied the students' telephone numbers. The data were collected by a polling company from May to July 2010. Prevalence ratios (PRs) and 95% confidence intervals (95% CI) were compared using the difference in proportions test suitable for large samples to analyze the association between asthma and sex.

RESULTS

In total, 3216 interviews from parents/caregivers of children were analyzed; 51.4% of the children were males. Mothers were the primary respondents (71.9%). The prevalence rates of "wheezing ever" and "wheezing in the last 12 months" were 52.2% and 20.9%, respectively, and were significantly higher among boys (PR: 1.10, 95% CI: 1.03-1.18 and PR: 1.27, 95% CI: 1.10-1.45). The same pattern was observed for "asthma ever" (PR: 1.44, 95% CI: 1.12-1.85) and for "severe asthma" (PR: 1.42, 95% CI: 1.11-1.82).

CONCLUSION

The prevalence of asthma was high among RJ's students. Most of the indicators of the disease were more prevalent among boys. Our results were similar to those observed in other Brazilian and international centers using the traditional ISAAC protocol. The use of this method can be an alternative for epidemiological studies of childhood asthma especially in areas where the telephone coverage is high.

Association between environmental factors and current asthma, rhinoconjunctivitis and eczema symptoms in school-aged children from Oropeza Province--Bolivia: a cross-sectional study

BACKGROUND

In recent years, the prevalence of asthma, rhinoconjunctivitis and eczema symptoms in childhood has considerably increased in developing countries including Bolivia, possibly due to changes in lifestyle, environmental and domestic factors. This study aimed to assess the association between environmental factors and asthma, rhinoconjuctivitis and eczema symptoms in school-aged children from Oropeza Province in Chuquisaca, Bolivia.

METHODS

A cross-sectional study was performed in 2340 children attending the fifth grade in 36 randomly selected elementary schools in Oropeza province. The prevalence of symptoms was determined using the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire. Environmental factors were assessed by the ISAAC environmental questionnaire including questions related to exposure to pets, farm animals, indoor and outdoor pollution, presence of disease vectors at home and precarious household conditions. Generalized linear mixed-effects models were adjusted for age, sex and place of living.

RESULTS

Thirty seven percent of children reported that at least one of their parents smoked at home. Wood or coal was used as cooking fuel in 19% of the homes and 29% reported intense truck traffic on the street where they lived. With respect to hygiene conditions, 86% reported exposure to dogs, 59% exposure to cats and 36% regular contact to farm animals. More than one precarious household condition was reported by 8% of children. In the adjusted model exposure to dog (adjusted OR 1.4; CI 95% 1.0-1.9), cat (1.2; 1.0-1.5), farm animals (1.5; 1.2-1.8); intense truck traffic (1.3; 1.0-1.6), parents smoking at home (1.2; 1.0-1.5), presence of disease vectors at home (fourth quartile vs. first quartile: 1.6; 1.2-2.3) and two or more precarious household conditions (1.5; 1.0-2.2) were significantly associated with rhinoconjunctivitis symptoms. The associations were similar for asthma and eczema symptoms; however it did not reach the level of statistical significance for all items.

CONCLUSION

Our results support previous findings reported for poor communities especially in Latin America, showing that lower hygiene conditions did not have protective effect against asthma and rhinoconjunctivitis and eczema symptoms.

Effects of geohelminth infection and age on the associations between allergen-specific IgE, skin test reactivity and wheeze: a case-control study

Background

Most childhood asthma in poor populations in Latin America is not associated with aeroallergen sensitization, an observation that could be explained by the attenuation of atopy by chronic helminth infections or effects of age.

Objective

To explore the effects of geohelminth infections and age on atopy, wheeze, and the association between atopy and wheeze.

Methods

A case-control study was done in 376 subjects (149 cases and 227 controls) aged 7–19 years living in rural communities in Ecuador. Wheeze cases, identified from a large cross-sectional survey, had recent wheeze and controls were a random sample of those without wheeze. Atopy was measured by the presence of allergen-specific IgE (asIgE) and skin prick test (SPT) responses to house dust mite and cockroach. Geohelminth infections were measured in stools and anti-Ascaris IgE in plasma.

Results

The fraction of recent wheeze attributable to anti-Ascaris IgE was 45.9%, while those for SPT and asIgE were 10.0% and 10.5% respectively. The association between atopy and wheeze was greater in adolescents than children. Although Anti-Ascaris IgE was strongly associated with wheeze (adj. OR 2.24 (95% CI 1.33–3.78, P = 0.003) and with asIgE (adj. OR 5.34, 95% CI 2.49–11.45, P < 0.001), the association with wheeze was independent of asIgE. There was some evidence that the association between atopy and wheeze was greater in uninfected subjects compared with those with active geohelminth infections.

Conclusions and clinical relevance

Atopy to house dust mite and cockroach explained few wheeze cases in our study population, while the presence of anti-Ascaris IgE was an important risk factor. Our data provided only limited evidence that active geohelminth infections attenuated the association between atopy and wheeze in endemic areas or that age modified this association. The role of allergic sensitization to Ascaris in the development of wheeze, independent of atopy, requires further investigation.

Trends in hospitalizations for respiratory diseases in Salvador, Bahia State, Brazil, 1998-2009

Respiratory diseases are the leading cause of hospitalizations in Brazil (excluding hospital admissions related to childbirth, pregnancy, and postpartum). To analyze the trend and seasonality of hospitalizations for respiratory diseases in Salvador, Bahia State, Brazil, 1998-2009, a time trend study was performed using simple linear regression. Hospitalization rates for all respiratory diseases and specifically for asthma, chronic obstructive pulmonary disease (COPD), and pneumonia were calculated by year and age group. Hospitalizations for all respiratory diseases decreased by 45.6% (β = -2.2; p < 0.001); those due to asthma showed the largest decline (annual average 1.2/10,000), pneumonia showed the largest reduction until 2002, subsequently tending to stabilize, and COPD remained unchanged. The under-5-year age group showed the largest decline in hospitalizations for all respiratory diseases. There was no seasonality in hospitalizations for COPD. There was a reduction in the burden of hospitalizations due to respiratory diseases in Salvador, mainly due to the drop in asthma and pneumonia in children < 5 years. However, the city still has hospitalization rates for respiratory diseases that are higher than in other large Brazilian cities.

Childhood asthma and allergies in urban, semiurban, and rural residential sectors in Chile

While rural living protects from asthma and allergies in many countries, results are conflicting in Latin America. We studied the prevalence of asthma and asthma symptoms in children from urban, semiurban, and rural sectors in south Chile. A cross-sectional questionnaire study was conducted in semiurban and rural sectors in the province of Valdivia (n = 559) using the ISAAC (International Study of Asthma and Allergies in Childhood) questionnaire. Results were compared to prevalence in urban Valdivia (n = 3105) by using data from ISAAC III study. Odds ratios (+95% confidence intervals) were calculated. No statistical significant differences were found for asthma ever and eczema symptoms stratified by residential sector, but a gradient could be shown for current asthma and rhinoconjunctivitis symptoms with urban living having highest and rural living having lowest prevalence. Rural living was inversely associated in a statistical significant way with current asthma (OR: 0.4; 95% CI: 0.2-0.9) and rhinoconjunctivitis symptoms (OR: 0.3; 95% CI: 0.2-0.7) in logistic regression analyses. Rural living seems to protect from asthma and respiratory allergies also in Chile, a South American country facing epidemiological transition. These data would be improved by clinical studies of allergic symptoms observed in studied sectors.

Dietary Patterns and Wheezing in the Midst of Nutritional Transition: A Study in Brazil

To assess the influence of dietary patterns on the prevalence of wheezing in the child and adolescent population in Northeastern Brazil. This is a cross-sectional study of male and female students, 6-12 years old, from the public elementary schools of São Francisco do Conde, Bahia, Northeastern Brazil. The report of wheezing in the past 12 months was collected using a questionnaire from the International Study of Asthma and Allergies in Childhood Program phase III, adapted to Portuguese. Consumption patterns were derived from principal component analysis based on the frequency of consumption of 97 food items by the food frequency questionnaire. We also obtained the anthropometric status, level of physical activity, pubertal development, and socioeconomic information, for each participant. Multivariate logistic regression analyses were used to assess the associations of interest. Of the children surveyed, 10.6% reported having wheezing. We identified 2 dietary patterns named Western and Prudent. We found a positive statistically significant association of the Western pattern with wheeze (odds ratio=1.77, 95% confidence interval: 1.10-2.84) after adjustment for total energy intake and controlling for potential confounders. The results showed that the Western dietary pattern was associated with wheezing. Our result is according with previous findings reported in several other studies.

Environmental conditions, immunologic phenotypes, atopy, and asthma: new evidence of how the hygiene hypothesis operates in Latin America

BACKGROUND

It has been proposed that improved hygiene and reduced experience of infections in childhood influences the development of allergic diseases. The mechanisms by which the hygiene operates are not well established but are underpinned by two apparently incompatible immunologic paradigms, the balance of TH1 versus TH2 cytokines and IL-10-mediated regulation of TH2 cytokines.

OBJECTIVE

This study defined immunologic phenotypes with the use of latent class analysis and investigated their associations with environmental factors, markers of allergy and asthma, in a Latin American population.

METHODS

We studied 1127 children living in urban Brazil. Data on wheeze and environmental exposures were collected with standardized questionnaires. Atopy was measured by specific IgE in serum and skin prick test reactivity to aeroallergens. Cytokines were measured in culture after the stimulation of peripheral blood leukocytes with mitogen. Infections with pathogens were assessed by serology and stool examinations. Children were classified as having high or low burden of infection. Latent class analysis was used to identify immune phenotypes on the basis of cytokine production. Logistic regression was used to evaluate the adjusted effects of environment and burden of infection on the immunologic phenotypes and the effect of the phenotypes on atopy and asthma.

RESULTS

Three phenotypes were identified, labeled underresponsive, intermediate, and responsive. Children of more educated mothers, living in improved environmental conditions, and with a low burden of infection were significantly more likely to have the responsive phenotype. The responsive phenotype was significantly associated with an increased prevalence of atopy but not asthma.

CONCLUSION

Our findings contribute to a better understanding of the immune mechanisms by which the hygiene hypothesis operates in urban Latin America.

The prevalence of wheezing and its association with body mass index and abdominal obesity in children

OBJECTIVE

To evaluate the relative importance of body mass index (BMI) and abdominal obesity in the prevalence of wheezing in Brazilian children.

MATERIALS AND METHODS

This is a cross-sectional study of male and female students, 6-12 years old, from the public elementary schools of São Francisco do Conde, Bahia, Northeast Brazil. Reports of wheezing in the past 12 months were collected using a questionnaire from the International Study of Asthma and Allergies in Childhood Program (ISAAC) phase III, adapted to Portuguese. Anthropometric, demographic, and socioeconomic information was collected. Multivariate logistic regression analyses were used to assess the associations of interest.

RESULTS

Of the children surveyed, 10.6% reported wheezing. Excess weight was observed in 16.2%, 10.5%, and 7.9% of the sample, measured by BMI, waist circumference (WC), and the waist-to-height ratio (WHtR), respectively. The percentage of patients with wheezing attributable to BMI ≥ 85th percentile (8.2%) slightly exceeded those identified with abdominal obesity, WC ≥ 80th percentile (7.3%) and WHtR > 0.5 (7.1%).

CONCLUSION

The results suggest that an excess of fat deposits, either in the abdominal region or elsewhere in the body, increased the risk of wheezing. Since obesity is an important public health problem worldwide, control of this problem may partially reduce the occurrence of wheezing in youth.

Asthma care in resource-poor settings

Asthma prevalence in low- to middle-income countries is at least the same or higher than in rich countries, but with increased severity. Lack of control in these settings is due to various factors such as low accessibility to effective medications, multiple and uncoordinated weak infrastructures of medical services for the management of chronic diseases such as asthma, poor compliance with prescribed therapy, lack of asthma education, and social and cultural factors. There is an urgent requirement for the implementation of better ways to treat asthma in underserved populations, enhancing the access to preventive medications and educational approaches with modern technological methods.

Urban vs. rural factors that affect adult asthma

In this review, our aim was to examine the influence of geographic variations on asthma prevalence and morbidity among adults, which is important for improving our understanding, identifying the burden, and for developing and implementing interventions aimed at reducing asthma morbidity. Asthma is a complex inflammatory disease of multifactorial origin, and is influenced by both environmental and genetic factors. The disparities in asthma prevalence and morbidity among the world's geographic locations are more likely to be associated with environmental exposures than genetic differences. In writing this article, we found that the indoor factors most consistently associated with asthma and asthma-related symptoms in adults included fuel combustion, mold growth, and environmental tobacco smoke in both urban and rural areas. Asthma and asthma-related symptoms occurred more frequently in urban than in rural areas, and that difference correlated with environmental risk exposures, SES, and healthcare access. Environmental risk factors to which urban adults were more frequently exposed than rural adults were dust mites,high levels of vehicle emissions, and a westernized lifestyle.Exposure to indoor biological contaminants in the urban environment is common.The main risk factors for developing asthma in urban areas are atopy and allergy to house dust mites, followed by allergens from animal dander. House dust mite exposure may potentially explain differences in diagnosis of asthma prevalence and morbidity among adults in urban vs. rural areas. In addition, the prevalence of asthma morbidity increases with urbanization. High levels of vehicle emissions,Western lifestyles and degree of urbanization itself, may affect outdoor and thereby indoor air quality. In urban areas, biomass fuels have been widely replaced by cleaner energy sources at home, such as gas and electricity, but in most developing countries, coal is still a major source of fuel for cooking and heating, particularly in winter. Moreover, exposure to ETS is common at home or at work in urban areas.There is evidence that asthma prevalence and morbidity is less common in rural than in urban areas. The possible reasons are that rural residents are exposed early in life to stables and to farm milk production, and such exposures are protective against developing asthma morbidity. Even so, asthma morbidity is disproportionately high among poor inner-city residents and in rural populations. A higher proportion of adult residents of nonmetropolitan areas were characterized as follows:aged 55 years or older, no previous college admission, low household income, no health insurance coverage, and could not see a doctor due to healthcare service availability, etc. In rural areas, biomass fuels meet more than 70% of the rural energy needs. Progress in adopting modern energy sources in rural areas has been slow. The most direct health impact comes from household energy use among the poor, who depend almost entirely on burning biomass fuels in simple cooking devices that are placed in inadequately ventilated spaces. Prospective studies are needed to assess the long-term effects of biomass smoke on lung health among adults in rural areas.Geographic differences in asthma susceptibility exist around the world. The reason for the differences in asthma prevalence in rural and urban areas may be due to the fact that populations have different lifestyles and cultures, as well as different environmental exposures and different genetic backgrounds. Identifying geographic disparities in asthma hospitalizations is critical to implementing prevention strategies,reducing morbidity, and improving healthcare financing for clinical asthma treatment. Although evidence shows that differences in the prevalence of asthma do exist between urban and rural dwellers in many parts of the world, including in developed countries, data are inadequate to evaluate the extent to which different pollutant exposures contribute to asthma morbidity and severity of asthma between urban and rural areas.

Does IFN-γ play a role on the pathogenesis of non-atopic asthma in Latin America children?

In this work we explore differences in blood cells and cytokine profiles in children according to atopic status and asthma (atopic or non-atopic). The study involved measurement of Th1(IFN-γ) and Th2 (IL-5 and IL-13) cytokines in Dermatophagoides pteronyssinus stimulated peripheral blood leukocytes, blood cell count, skin prick test and specific IgE against common aeroallergens. Atopic status was associated with eosinophilia and production of Th2 type cytokines. Atopic asthma was associated with eosinophilia and non-atopic asthma was associated with IFN-γ and elevated monocytes in blood. IFN-γ and monocytes might play a role in immunopathology of non-atopic asthma in Latin American children.

Upper airways microbiota in antibiotic-naïve wheezing and healthy infants from the tropics of rural Ecuador

Background

Observations that the airway microbiome is disturbed in asthma may be confounded by the widespread use of antibiotics and inhaled steroids. We have therefore examined the oropharyngeal microbiome in early onset wheezing infants from a rural area of tropical Ecuador where antibiotic usage is minimal and glucocorticoid usage is absent.

Materials and Methods

We performed pyrosequencing of amplicons of the polymorphic bacterial 16S rRNA gene from oropharyngeal samples from 24 infants with non-infectious early onset wheezing and 24 healthy controls (average age 10.2 months). We analyzed microbial community structure and differences between cases and controls by QIIME software.

Results

We obtained 76,627 high quality sequences classified into 182 operational taxonomic units (OTUs). Firmicutes was the most common and diverse phylum (71.22% of sequences) with Streptococcus being the most common genus (49.72%). Known pathogens were found significantly more often in cases of infantile wheeze compared to controls, exemplified by Haemophilus spp. (OR = 2.12, 95% Confidence Interval (CI) 1.82–2.47; P = 5.46×10⁻²³) and Staphylococcus spp. (OR = 124.1, 95%CI 59.0–261.2; P = 1.87×10⁻²⁴¹). Other OTUs were less common in cases than controls, notably Veillonella spp. (OR = 0.59, 95%CI = 0.56–0.62; P = 8.06×10⁻⁸⁶).

Discussion

The airway microbiota appeared to contain many more Streptococci than found in Western Europe and the USA. Comparisons between healthy and wheezing infants revealed a significant difference in several bacterial phylotypes that were not confounded by antibiotics or use of inhaled steroids. The increased prevalence of pathogens such as Haemophilus and Staphylococcus spp. in cases may contribute to wheezing illnesses in this age group.

Temporal trends of asthma mortality rates in Brazil from 1980 to 2010

OBJECTIVE

Mortality from asthma has varied among countries during the last several decades. This study aimed to identify temporal trends of asthma mortality in Brazil from 1980 to 2010.

METHOD

We analyzed 6840 deaths of patients aged 5-34 years that occurred in Brazil with the underlying cause of asthma. We applied a log-linear model using Poisson regression to verify peaks and trends. We also calculated the point estimation and 95% confidence interval (CI 95%) of the annual percent change (APC) of the mortality rates, and the average annual percent change (AAPC) for 2001-2010.

RESULTS

A decline was observed from 1980 to 1992 [APC = -3.4 (-5.0 to -1.8)], followed by a nonsignificant rise until 1996 [APC = 6.8 (-1.4 to 15.6)], and a new downward trend from 1997 to 2010 [APC = -2.7 (-3.9 to -1.6)]. The APCs varied according to age strata: 5-14 years from 1980 to 2010 [-0.3 (-1.1 to 0.5)]; 15-24 years from 1980 to 1991 [-2.1 (-5.0 to 0.9)], from 1992 to 1996 [6.8 (-6.7 to 22.2)], and from 1997 to 2010 [-3.9 (-5.7 to -2.0)]; 24-25 years from 1980 to 1992 [-2.5 (-4.6 to -0.3)], from 1993 to 1995 [12.0 (-21.1 to 59.1)], and from 1996-2010 [-1.7 (-3.0 to -0.4)]. AAPC from 2001 to 2010 was -1.7 (-3.0 to -0.4); the decline for this period was significant for patients over 15 years old, women, and those living in the Southeast region.

CONCLUSION

Asthma mortality rates in Brazil have been declining since the late 1990s.

Prevalência de fatores de risco e proteção para doenças crônicas nas capitais do Brasil - principais resultados do Vigitel 2010

OBJETIVO: descrever os principais fatores de risco e proteção para doenças crônicas com dados do inquérito telefônico de 2010. METODOLOGIA: entrevistas telefônicas realizadas em amostra probabilística dos adultos residentes nas capitais do Brasil e Distrito Federal com telefone fixo residencial. As prevalências foram estratificadas por sexo, idade e escolaridade. RESULTADOS: Foi verificado alto consumo de refrigerantes (28%), de carne com gordura (46%) e de consumo abusivo de álcool (18%), e baixo consumo de frutas e hortaliças (18%) e de atividade física no lazer (15%). Aproximadamente metade da população referiu ter excesso de peso e não se proteger da radiação solar. A inatividade física e o tabagismo atingem cerca de 15% dos adultos. Fatores de risco foram mais prevalentes em homens, adultos jovens e de menor escolaridade. CONCLUSÃO: os resultados apontam diferentes comportamentos em saúde da população segundo características sociodemográficas. Essa variabilidade deve ser considerada nas ações de promoção de saúde.

Community violence and childhood asthma prevalence in peripheral neighborhoods in Salvador, Bahia State, Brazil

This study aimed to identify degrees of exposure to community violence reported by parents and guardians of children from four to 12 years of age and the association with childhood asthma symptoms. A cross-sectional study was conducted with 1,232 parents/guardians in 24 peripheral neighborhoods in Salvador, the capital of Bahia State, Brazil. The authors investigated asthma symptoms in children and acts of violence in the community. More than 75% of parents/guardians had been exposed to community violence in the previous year, with 20% reporting high levels of exposure. Children that were more exposed to violence showed higher asthma prevalence (28.4%) as compared to non-exposed children (16.4%). Children exposed to maximum levels of violence were nearly twice as likely to present asthma symptoms (adjusted OR = 1.94; 95%CI: 1.12-3.36). The study highlighted the relevance of community violence as a risk factor for asthma and the need for further research to elucidate methodological issues.

Prevalence of asthma and other allergic conditions in Colombia 2009-2010: a cross-sectional study

Background

While it is suggested that the prevalence of asthma in developed countries may have stabilized, this is not clear in currently developing countries. Current available information for both adults and children simultaneously on the burden and impact of allergic conditions in Colombia and in many Latin American countries is limited. The objectives of this study were to estimate the prevalence for asthma, allergic rhinitis (AR), atopic eczema (AE), and atopy in six colombian cities; to quantify costs to the patient and her/his family; and to determine levels of Immunoglobulin E (IgE) in asthmatic and healthy subjects.

Methods

We conducted a cross-sectional, population-based study in six cities during the academic year 2009–2010. We used a school-based design for subjects between 5–17 years old. We carried out a community-based strategy for subjects between 1–4 years old and adults between 18–59 years old. Serum samples for total and antigen-specific (IgE) levels were collected using a population-based, nested, case–control design.

Results

We obtained information on 5978 subjects. The largest sample of subjects was collected in Bogotá (2392). The current prevalence of asthma symptoms was 12% (95% CI, 10.5-13.7), with 43% (95% CI, 36.3-49.2) reporting having required an emergency department visit or hospitalization in the past 12 months. Physician diagnosed asthma was 7% (95% CI, 6.1-8.0). The current prevalence of AR symptoms was 32% (95% CI, 29.5-33.9), and of AE symptoms was 14% (95% CI, 12.5-15.3). We collected blood samples from 855 subjects; 60.2% of asthmatics and 40.6% of controls could be classified as atopic.

Conclusions

In Colombia, symptom prevalence for asthma, AR and AE, as well as levels of atopy, are substantial. Specifically for asthma, symptom severity and absence from work or study due to symptoms are important. These primary care sensitive conditions remain an unmet public health burden in developing countries such as Colombia.

Asthma and allergies in Jamaican children aged 2-17 years: a cross-sectional prevalence survey

OBJECTIVE

To determine the prevalence and severity of asthma and allergies as well as risk factors for asthma among Jamaican children aged 2-17 years.

DESIGN

A cross-sectional, community-based prevalence survey using the International Study of Asthma and Allergies in Childhood questionnaire. The authors selected a representative sample of 2017 children using stratified, multistage cluster sampling design using enumeration districts as primary sampling units.

SETTING

Jamaica, a Caribbean island with a total population of approximately 2.6 million, geographically divided into 14 parishes.

PARTICIPANTS

Children aged 2-17 years, who were resident in private households. Institutionalised children such as those in boarding schools and hospitals were excluded from the survey.

PRIMARY AND SECONDARY OUTCOME MEASURES

The prevalence and severity of asthma and allergy symptoms, doctor-diagnosed asthma and risk factors for asthma.

RESULTS

Almost a fifth (19.6%) of Jamaican children aged 2-17 years had current wheeze, while 16.7% had self-reported doctor-diagnosed asthma. Both were more common among males than among females. The prevalence of rhinitis, hay fever and eczema among children was 24.5%, 25% and 17.3%, respectively. Current wheeze was more common among children with rhinitis in the last 12 months (44.3% vs 12.6%, p<0.001), hay fever (36.8% vs 13.8%, p<0.001) and eczema (34.1% vs 16.4%, p<0.001). Independent risk factors for current wheeze (ORs, 95% CI) were chest infections in the first year of life 4.83 (3.00 to 7.77), parental asthma 4.19 (2.8 to 6.08), rhinitis in the last 12 months 6.92 (5.16 to 9.29), hay fever 4.82 (3.62 to 6.41), moulds in the home 2.25 (1.16 to 4.45), cat in the home 2.44 (1.66 to 3.58) and dog in the home 1.81 (1.18 to 2.78).

CONCLUSIONS

The prevalence of asthma and allergies in Jamaican children is high. Significant risk factors for asthma include chest infections in the first year of life, a history of asthma in the family, allergies, moulds and pets in the home.

The interplay between diet and emerging allergy: what can we learn from Indigenous Australians?

The pathophysiology of atopic diseases, including asthma and allergy, is the result of complex gene-environment interactions. Since European colonization the Indigenous population of Australia has undergone significant changes with respect to their lifestyle as hunter-gatherers. These changes have had a detrimental effect on Aboriginal health, in part due to immunological modification. This review provides a comparative look at both the traditional Aboriginal/Indigenous diet and modern Western diets, examines some common allergies increasingly reported in contemporary Indigenous populations, and reviews concepts such the effect of vitamin deficiencies and changes in gut microbiota on immune function.

Maternal mental health and social support: effect on childhood atopic and non-atopic asthma symptoms

BACKGROUND

Atopic and non-atopic asthma have distinct risk factors and immunological mechanisms, and few studies differentiate between the impacts of psychosocial factors on the prevalence of these disease phenotypes. The authors aimed to identify whether the effect of maternal mental health on prevalence of asthma symptoms differs between atopic and non-atopic children, taking into account family social support.

METHODS

This is a cross-sectional study of 1013 children participating in the Social Change Allergy and Asthma in Latin America project. Psychosocial data were collected through a household survey utilising Self-Reporting Questionnaire and Medical Outcome Study Social Support Scale. Socioeconomic and wheezing information was obtained through the questionnaire of the International Study of Allergy and Asthma in Childhood, and level of allergen-specific IgE was measured to identify atopy. Polytomous logistic regression was used to estimate the association between maternal mental health, social support and atopic and non-atopic wheezing. Effect modification was evaluated through stratified polytomous regression according to social support level.

RESULTS

Maternal mental disorder had the same impact on atopic and non-atopic wheezing, even after adjusting for confounding variables. Affective, material and informational supports had protective effects on non-atopic asthma, and there is some evidence that social supports may act as a buffer for the impact of maternal mental disorder on non-atopic wheezing.

CONCLUSION

Poor maternal mental health is positively associated with wheezing, independent of whether asthma is atopic or non-atopic, but perception of high levels of social support appears to buffer this relationship in non-atopic wheezers only.

Particular characteristics of allergic symptoms in tropical environments: follow up to 24 months in the FRAAT birth cohort study

Background

Early wheezing and asthma are relevant health problems in the tropics. Mite sensitization is an important risk factor, but the roles of others, inherent in poverty, are unknown. We designed a birth-cohort study in Cartagena (Colombia) to investigate genetic and environmental risk factors for asthma and atopy, considering as particular features perennial exposure to mites, parasite infections and poor living conditions.

Methods

Pregnant women representative of the low-income suburbs of the city were randomly screened for eligibility at delivery; 326 mother-infant pairs were included at baseline and biological samples were collected from birth to 24 months for immunological testing, molecular genetics and gene expression analysis. Pre and post-natal information was collected using questionnaires.

Results

94% of families were from the poorest communes of the city, 40% lacked sewage and 11% tap-water. Intestinal parasites were found as early as 3 months; by the second year, 37.9% of children have had parasites and 5.22% detectable eggs of Ascaris lumbricoides in stools (Median 3458 epg, IQR 975-9256). The prevalence of "wheezing ever" was 17.5% at 6 months, 31.1% at 12 months and 38.3% at 24 months; and recurrent wheezing (3 or more episodes) 7.1% at 12 months and 14.2% at 24 months. Maternal rhinitis [aOR 3.03 (95%CI 1.60-5.74), p = 0.001] and male gender [aOR 2.09 (95%CI 1.09 - 4.01), p = 0.026], increased risk for wheezing at 6 months. At 24 months, maternal asthma was the main predisposing factor for wheezing [aOR 3.65 (95%CI 1.23-10.8), p = 0.01]. Clinical symptoms of milk/egg allergy or other food-induced allergies were scarce (1.8%) and no case of atopic eczema was observed.

Conclusions

Wheezing is the most frequent phenotype during the first 24 months of life and is strongly associated with maternal asthma. At 24 months, the natural history of allergic symptoms is different to the "atopic march" described in some industrialized countries. This cohort is representative of socially deprived urban areas of underdeveloped tropical countries. The collection of biological samples, data on exposure and defined phenotypes, will contribute to understand the gene/environment interactions leading to allergy inception and evolution.

Time trend of asthma in children and adolescents in Brazil, 1998-2008

OBJECTIVE

To analyze the trends in asthma prevalence in children and adolescents between 1998 and 2008 in Brazil.

METHODS

Data on asthma prevalence from the 1998, 2003 and 2008 National Household Sample Surveys were analyzed. The sample was comprised of 141,402, 144,443 and 134,032 individuals in 1998, 2003 and 2008, respectively, and the analysis was adjusted for the sample design. Trends in asthma prevalence were described for sex, Brazilian regions and place of residence of children (zero to nine years of age) and adolescents (ten to 19 years of age).

RESULTS

The prevalence of asthma in children was 7.7% in 1998, 8.1% in 2003 and 8.5% in 2008, with an annual increase of 1%. The highest annual increase was observed in the Southeast and North regions (1.4%). Among adolescents, the prevalence of asthma was 4.4% in 1998, 5.0% in 2003 and 5.5% in 2008, with an increase of 2.2% per year. In the Northeast region, the annual increase in the prevalence of asthma was 3.5%. The greatest increases were observed in boys and in residents of rural areas.

CONCLUSIONS

Although asthma has decreased in some developing countries, the results found in Brazil point to an increase in this disease in children and adolescents between 1998 and 2008, especially in rural areas.

The effect of single and multiple infections on atopy and wheezing in children

BACKGROUND

The current epidemic of asthma and atopy has been explained by alterations in immune responses related to reduction in childhood infections. However, the findings of epidemiologic studies investigating the association between infection with atopy and asthma have been inconsistent.

OBJECTIVE

We sought to investigate the effect of single or multiple infections (pathogen burden) on atopy and wheeze in urban children from Latin America.

METHODS

Specific IgE against aeroallergens (sIgE) and skin prick test (SPT) reactivity for the most common local allergens were measured in 1128 children aged 4 to 11 years. Data on wheezing and potential confounders were collected by questionnaire. Infections by 8 pathogens were assessed by using serology and stool examination. Associations of wheeze and atopic outcomes with single and multiple infections were analyzed by means of logistic regression.

RESULTS

Negative results for Toxoplasma gondii were associated with a higher prevalence of sIgE (≥0.70 kU/L), whereas negative results for Ascaris lumbricoides, T gondii, herpes simplex virus, and EBV were associated with a higher prevalence of SPT reactivity. Children with 3 or fewer infection markers had a higher prevalence of sIgE and SPT reactivity compared with those with 4 or more infection markers. However, isolated infections or pathogen burden were not associated with the prevalence of atopic or nonatopic wheeze.

CONCLUSION

The findings provide support for the idea that the hygiene hypothesis is operating in an urban Latin American context, but its expression is thus far restricted to the atopic status of patients and not the perceived asthma symptoms.

Behavior problems and prevalence of asthma symptoms among Brazilian children

OBJECTIVE

Asthma is the most common chronic disease in childhood and has been designated a public health problem due to the increase in its prevalence in recent decades, the amount of health service expenditure it absorbs and an absence of consensus about its etiology. The relationships among psychosocial factors and the occurrence, symptomatology, and severity of asthma have recently been considered. There is still controversy about the association between asthma and a child's mental health, since the pathways through which this relationship is established are complex and not well researched. This study aims to investigate whether behavior problems are associated with the prevalence of asthma symptoms in a large urban center in Latin America.

METHODS

It is a cross-section study of 869 children between 6 and 12 years old, residents of Salvador, Brazil. The International Study of Allergy and Asthma in Childhood (ISAAC) instrument was used to evaluate prevalence of asthma symptoms. The Child Behavior Checklist (CBCL) was employed to evaluate behavioral problems.

RESULTS

19.26% (n=212) of the children presented symptoms of asthma. 35% were classified as having clinical behavioral problems. Poisson's robust regression model demonstrated a statistically significant association between the presence of behavioral problems and asthma symptoms occurrence (PR: 1.43; 95% CI: 1.10-1.85).

CONCLUSION

These results suggest an association between behavioral problems and pediatric asthma, and support the inclusion of mental health care in the provision of services for asthma morbidity.

Urbanisation is associated with prevalence of childhood asthma in diverse, small rural communities in Ecuador

Background

Studies conducted in transitional communities from Africa and Asia have pointed to the process of urbanisation as being responsible for the increase in asthma prevalence in developing regions. In Latin America, there are few published data available on the potential impact of urbanisation on asthma prevalence. The aim of the present study was to explore how the process of urbanisation may explain differences in asthma prevalence in transitional communities in north-eastern Ecuador.

Methodology/principal findings

An ecological study was conducted in 59 communities in Esmeraldas Province, Ecuador. Indicators of urbanisation were grouped into three indices representing the processes associated with urbanisation: socioeconomic, lifestyle and urban infrastructure. Categorical principal components analysis was used to generate scores for each index and a fourth index—a summary urbanisation index—was derived from the most representative variables in each of the three indices. The authors analysed the associations between community asthma prevalence and the indices, as well as with each indicator variable of every group. The overall prevalence of asthma was 10.1% (range 0–31.4% between communities). Three of the four indices presented significant associations with community asthma prevalence: socioeconomic (r=0.295, p=0.023), lifestyle (r=0.342, p=0.008) and summary urbanisation index (r=0.355, p=0.006). Variables reflecting better socioeconomic status and a more urban lifestyle were associated with greater asthma prevalence.

Conclusions

These data provide evidence that the prevalence of asthma increases with increasing levels of urbanisation in transitional communities, and factors associated with greater socioeconomic level and changes towards a more urban lifestyle may be particularly important.

A review of equity issues in quantitative studies on health inequalities: the case of asthma in adults

BACKGROUND

The term 'inequities' refers to avoidable differences rooted in injustice. This review examined whether or not, and how, quantitative studies identifying inequalities in risk factors and health service utilization for asthma explicitly addressed underlying inequities. Asthma was chosen because recent decades have seen strong increases in asthma prevalence in many international settings, and inequalities in risk factors and related outcomes.

METHODS

A review was conducted of studies that identified social inequalities in asthma-related outcomes or health service use in adult populations. Data were extracted on use of equity terms (objective evidence), and discussion of equity issues without using the exact terms (subjective evidence).

RESULTS

Of the 219 unique articles retrieved, 21 were eligible for inclusion. None used the terms equity/inequity. While all but one article traced at least partial pathways to inequity, only 52% proposed any intervention and 55% of these interventions focused exclusively on the more proximal, clinical level.

CONCLUSIONS

Without more in-depth and systematic examination of inequities underlying asthma prevalence, quantitative studies may fail to provide the evidence required to inform equity-oriented interventions to address underlying circumstances restricting opportunities for health.

Pattern of asthma medication use among children from a large urban center in Brazil

PURPOSE

Despite the advances in asthma therapeutics, there are few data on the use and determinants of anti-asthmatic drugs in the general population of children. This study describes the use of asthma medications among children in the general population and in children with current asthma, living in a large urban center in Brazil.

METHODS

A population-based cross-sectional survey, aimed at analyzing asthma determinants, was conducted with 1,382 children aged 4-11 years, between February and May 2006, in Salvador, Brazil. At baseline, an extensive questionnaire was applied, including questions about the use of asthma medications in the last 12 months.

RESULTS

In all studied children (n = 1,382) aged 4-11 years, oral beta2-agonists were the drugs most frequently used (9.8%), followed by short-acting inhaled beta2-agonists (4.3%) and systemic corticosteroids (1.6%). Anti-asthmatic drug use was higher among males than females, and it significantly decreased with age in both genders. A total of 312 children (22.6%) reported current asthma, and 62% of them were not being treated with any anti-asthmatic drugs. Of all those who reported following a certain type of treatment, 20% used oral beta2-agonists alone; 6.1%, short-acting inhaled beta2-agonists alone; and 4.8%, a combination of both drugs. Anti-asthmatic drug use did not differ according to socioeconomic status, except for the use of inhaled beta2-agonists and systemic corticosteroids.

CONCLUSIONS

An overwhelming majority of asthmatic children were not using long-term medications for asthma, in particular inhaled corticosteroids, regardless of the severity of their disease. This result points to the deficiencies of the Brazilian public health system in recognizing this important pharmacological need for child care and thereby limiting the access of these children to a group of efficacious, available, and low risk therapeutic medications.

Chronic non-communicable diseases in Brazil: burden and current challenges

Non-communicable diseases (NCDs) have become a major health priority in Brazil--72% of all deaths were attributable to NCDs in 2007. They are also the main source of disease burden, with neuropsychiatric disorders being the single largest contributor. Morbidity and mortality due to NCDs are greatest in the poor population. Although the crude NCD mortality increased 5% between 1996 and 2007, age-standardised mortality declined by 20%. Declines were primarily for cardiovascular and chronic respiratory diseases, in association with the successful implementation of health policies that lead to decreases in smoking and the expansion of access to primary health care. Of note, however, the prevalence of diabetes and hypertension is rising in parallel with that of excess weight; these increases are associated with unfavourable changes of diet and physical activity. Brazil has implemented major policies for the prevention of NCDs, and its age-adjusted NCD mortality is falling by 1·8% per year. However, the unfavourable trends for most major risk factors pose an enormous challenge and call for additional and timely action and policies, especially those of a legislative and regulatory nature and those providing cost-effective chronic care for individuals affected by NCDs.

Environmental risk factors in the first year of life and childhood asthma in the Central South of Chile

BACKGROUND

Childhood asthma has a high prevalence in South America--a region of the world currently undergoing a thorough modernization and transition process. Asthma in South America is mainly associated with poor urban environment, which actually may challenge the role of the hygiene hypothesis. We systematically assessed the impact of environmental factors in the first year of life on asthma.

METHODS

A case-control study including 188 asthmatics and 294 hospital-based controls aged 6-15 years was carried out in the Central South of Chile. Parents of study participants completed a computer-assisted interview on environmental factors (such as birth order, day-care attendance, pneumonia infection, regular animal and furry pet contact, and environmental tobacco smoke exposure) in the first year of life and potential confounders. Atopy was assessed using skin prick tests. Multivariate logistic regression models were calculated to assess the association between exposures and asthma, adjusting for potential confounders.

RESULTS

Day-care attendance (OR = 0.31; 95% CI: 0.10, 0.94) and regular farm animal contact (OR = 0.38; 95% CI: 0.17, 0.85) were inversely related to childhood asthma in the logistic regression models. Pneumonia infection (OR = 2.24; 95% CI: 1.21, 4.16) and mold or dampness in the home (OR = 1.87; 95% CI: 1.18, 2.97) in the first year of life were positively associated with asthma.

CONCLUSION

Our results suggest that the hygiene hypothesis is also applicable in the Chilean setting, a South American country in epidemiological transition.

MeDALL (Mechanisms of the Development of ALLergy): an integrated approach from phenotypes to systems medicine

The origin of the epidemic of IgE-associated (allergic) diseases is unclear. MeDALL (Mechanisms of the Development of ALLergy), an FP7 European Union project (No. 264357), aims to generate novel knowledge on the mechanisms of initiation of allergy and to propose early diagnosis, prevention, and targets for therapy. A novel phenotype definition and an integrative translational approach are needed to understand how a network of molecular and environmental factors can lead to complex allergic diseases. A novel, stepwise, large-scale, and integrative approach will be led by a network of complementary experts in allergy, epidemiology, allergen biochemistry, immunology, molecular biology, epigenetics, functional genomics, bioinformatics, computational and systems biology. The following steps are proposed: (i) Identification of 'classical' and 'novel' phenotypes in existing birth cohorts; (ii) Building discovery of the relevant mechanisms in IgE-associated allergic diseases in existing longitudinal birth cohorts and Karelian children; (iii) Validation and redefinition of classical and novel phenotypes of IgE-associated allergic diseases; and (iv) Translational integration of systems biology outcomes into health care, including societal aspects. MeDALL will lead to: (i) A better understanding of allergic phenotypes, thus expanding current knowledge of the genomic and environmental determinants of allergic diseases in an integrative way; (ii) Novel diagnostic tools for the early diagnosis of allergy, targets for the development of novel treatment modalities, and prevention of allergic diseases; (iii) Improving the health of European citizens as well as increasing the competitiveness and boosting the innovative capacity of Europe, while addressing global health issues and ethical issues.

Immune system development during early childhood in tropical Latin America: evidence for the age-dependent down regulation of the innate immune response

The immune response that develops in early childhood underlies the development of inflammatory diseases such as asthma and there are few data from tropical Latin America (LA). This study investigated the effects of age on the development of immunity during the first 5 years of life by comparing innate and adaptive immune responses in Ecuadorian children aged 6–9 months, 22–26 months, and 48–60 months. Percentages of naïve CD4+ T cells declined with age while those of memory CD4⁺ and CD8⁺ T cells increased indicating active development of the immune system throughout the first five years. Young infants had greater innate immune responses to TLR agonists compared to older children while regulatory responses including SEB-induced IL-10 and percentages of FoxP3⁺ T-regulatory cells decreased with age. Enhanced innate immunity in early life may be important for host defense against pathogens but may increase the risk of immunopathology.

Environmental health indicators and a case study of air pollution in Latin American cities

Environmental health indicators (EHIs) are applied in a variety of research and decision-making settings to gauge the health consequences of environmental hazards, to summarize complex information, or to compare policy impacts across locations or time periods. While EHIs can provide a useful means of conveying information, they also can be misused. Additional research is needed to help researchers and policy-makers understand categories of indicators and their appropriate application. In this article, we review current frameworks for environmental health indicators and discuss the advantages and limitations of various forms. A case study EHI system was developed for air pollution and health for urban Latin American centers in order to explore how underlying assumptions affect indicator results. Sixteen cities were ranked according to five indicators that considered: population exposed, children exposed, comparison to health-based guidelines, and overall PM(10) levels. Results indicate that although some overall patterns in rankings were observed, cities' relative rankings were highly dependent on the indicator used. In fact, a city that was ranked best under one indicator was ranked worst with another. The sensitivity of rankings, even when considering a simple case of a single pollutant, highlights the need for clear understanding of EHIs and how they may be affected by underlying assumptions. Careful consideration should be given to the purpose, assumptions, and limitations of EHIs used individually or in combination in order to minimize misinterpretation of their implications and enhance their usefulness.

Poverty, dirt, infections and non-atopic wheezing in children from a Brazilian urban center

BACKGROUND

The causation of asthma is poorly understood. Risk factors for atopic and non-atopic asthma may be different. This study aimed to analyze the associations between markers of poverty, dirt and infections and wheezing in atopic and non-atopic children.

METHODS

1445 children were recruited from a population-based cohort in Salvador, Brazil. Wheezing was assessed using the ISAAC questionnaire and atopy defined as allergen-specific IgE ≥ 0.70 kU/L. Relevant social factors, environmental exposures and serological markers for childhood infections were investigated as risk factors using multivariate multinomial logistic regression.

RESULTS

Common risk factors for wheezing in atopic and non-atopic children, respectively, were parental asthma and respiratory infection in early childhood. No other factor was associated with wheezing in atopic children. Factors associated with wheezing in non-atopics were low maternal educational level (OR 1.49, 95% CI 0.98-2.38), low frequency of room cleaning (OR 2.49, 95% CI 1.27-4.90), presence of rodents in the house (OR 1.48, 95% CI 1.06-2.09), and day care attendance (OR 1.52, 95% CI 1.01-2.29).

CONCLUSIONS

Non-atopic wheezing was associated with risk factors indicative of poverty, dirt and infections. Further research is required to more precisely define the mediating exposures and the mechanisms by which they may cause non-atopic wheeze.

Risk factors for atopic and non-atopic asthma in a rural area of Ecuador

Background

Asthma has emerged as an important public health problem of urban populations in Latin America. Epidemiological data suggest that a minority of asthma cases in Latin America may be associated with allergic sensitisation and that other mechanisms causing asthma have been overlooked. The aim of the present study was to investigate risk factors for atopic and non-atopic asthma in school-age children.

Methods

A cross-sectional study was conducted among 3960 children aged 6–16 years living in Afro-Ecuadorian rural communities in Esmeraldas province in Ecuador. Allergic diseases and risk factors were assessed by questionnaire and allergic sensitisation by allergen skin prick reactivity.

Results

A total of 390 (10.5%) children had wheeze within the previous 12 months, of whom 14.4% had at least one positive skin test. The population-attributable fraction for recent wheeze associated with atopy was 2.4%. Heavy Trichuris trichiura infections were strongly inversely associated with atopic wheeze. Non-atopic wheeze was positively associated with maternal allergic symptoms and sedentarism (watching television (>3 h/day)) but inversely associated with age and birth order.

Conclusions

The present study showed a predominance of non-atopic compared with atopic wheeze among schoolchildren living in a poor rural region of tropical Latin America. Distinct risk factors were associated with the two wheeze phenotypes and may indicate different causal mechanisms. Future preventive strategies in such populations may need to be targeted at the causes of non-atopic wheeze.

Long-term periodic anthelmintic treatments are associated with increased allergen skin reactivity

Background

The low prevalence of allergic disease in the rural tropics has been attributed to the protective effects of chronic helminth infections. There is concern that treatment-based control programmes for these parasites may lead to an increase in the prevalence of allergic diseases.

Objective

We measured the impact of 15–17 years of anthelmintic treatment with ivermectin on the prevalence of allergen skin test reactivity and allergic symptoms in school-age children.

Methods

The prevalence of allergen skin test reactivity, exercise-induced bronchospasm and allergic symptoms was compared between school-age children living in communities that had received community-based treatments with ivermectin (for onchocerciasis control) for a period of 15–17 years with those living in geographically adjacent communities that had received no ivermectin.

Results

The prevalence of allergen skin test reactivity was double in children living in treated communities compared with those in untreated communities (16.7% vs. 8.7%, adjusted OR 2.10, 95% CI 1.50–2.94, P<0.0001), and the effect was mediated partly by a reduced prevalence of Trichuris trichiura among treated children. Ivermectin treatments were associated with an increased prevalence of recent eczema symptoms (adjusted OR 2.24, 95% CI 1.05–4.78, P=0.04) but not symptoms of asthma or rhino-conjunctivitis. The effect on eczema symptoms was not associated with reductions in geohelminth infections.

Conclusion

Long-term periodic treatments with ivermectin were associated with an increased prevalence of allergen skin test reactivity. There was some evidence that treatment was associated with an increased prevalence of recent eczema symptoms but not those of asthma or rhino-conjunctivitis.

Cite this as: P. Endara, M. Vaca, M. E. Chico, S. Erazo, G. Oviedo, I. Quinzo, A. Rodriguez R. Lovato, A.-L. Moncayo, M. L. Barreto, L. C. Rodrigues and P. J. Cooper, Clinical & Experimental Allergy, 2010 (40) 1669–1677.

Asthma in changing environments--chances and challenges of international research collaborations between South America and Europe--study protocol and description of the data acquisition of a case-control-study

Background

Asthma in children is an emerging public health problem in South America. So far, research in this part of the world is limited. This paper presents the methodology and description of the data acquisition of an asthma case-control study conducted in the Central South of Chile.

Methods/Design

A hospital-based case-control study about asthma (188 cases, 294 controls) in children (6-15 years) was carried out in Valdivia, Chile between November 2008 and December 2009. Data on asthma risk factors were collected by computer-assisted personal interview using validated questions from e.g. ISAAC phase II. Data on household dust exposure (endotoxin, allergen analyses), skin prick tests to most common allergens, stool examinations for parasitic infection, and blood samples (total IgE, genetics) were collected. Additionally, 492 randomly chosen blood donors were recruited in order to assess allele frequencies in the population of Valdivia.

Discussion

Overall 1,173 participants were contacted. Response was 82% among cases and 65% among controls. Atopic sensitization was high (78% among cases, 47% among controls). Cases had a statistically significantly (p < .0001) increased self-reported 12-month prevalence of symptoms of rhinitis (82% vs. 51%) and wheeze (68% vs. 16%). The study is well placed to address current hypotheses about asthma and its correlates in the South American context. Results of this study might help develop novel, innovative and individualized prevention strategies in countries in transition with respect to the South American context.

Recent perspectives on global epidemiology of asthma in childhood

New research in asthma epidemiology in children includes the development of the ISAAC programme, which has shown large variations globally in the prevalence of asthma symptoms. Time trends in the prevalence of asthma symptoms have shown a mixed picture of increases in low prevalence centres, and a plateau or even a decrease in high prevalence centres. A range of environmental factors have been studied and some potentially protective associations have been found, as well as potentially aggravating factors. Atopy has less influence on the prevalence of symptoms of asthma in low and middle income countries. Breast feeding exerts a protective effect only on non-atopic asthma in non-affluent countries. Future research should explore these areas further.

Which population level environmental factors are associated with asthma, rhinoconjunctivitis and eczema? Review of the ecological analyses of ISAAC Phase One

The International Study of Asthma and Allergies in Childhood (ISAAC) Phase One showed large worldwide variations in the prevalence of symptoms of asthma, rhinoconjunctivitis and eczema, up to 10 to 20 fold between countries. Ecological analyses were undertaken with ISAAC Phase One data to explore factors that may have contributed to these variations, and are summarised and reviewed here.In ISAAC Phase One the prevalence of symptoms in the past 12 months of asthma, rhinoconjunctivitis and eczema were estimated from studies in 463,801 children aged 13 - 14 years in 155 centres in 56 countries, and in 257,800 children aged 6-7 years in 91 centres in 38 countries. Ecological analyses were undertaken between symptom prevalence and the following: Gross National Product per capita (GNP), food intake, immunisation rates, tuberculosis notifications, climatic factors, tobacco consumption, pollen, antibiotic sales, paracetamol sales, and outdoor air pollution.Symptom prevalence of all three conditions was positively associated with GNP, trans fatty acids, paracetamol, and women smoking, and inversely associated with food of plant origin, pollen, immunisations, tuberculosis notifications, air pollution, and men smoking. The magnitude of these associations was small, but consistent in direction between conditions. There were mixed associations of climate and antibiotic sales with symptom prevalence.The potential causality of these associations warrant further investigation. Factors which prevent the development of these conditions, or where there is an absence of a positive correlation at a population level may be as important from the policy viewpoint as a focus on the positive risk factors. Interventions based on small associations may have the potential for a large public health benefit.

Interactions between helminth parasites and allergy

PURPOSE OF REVIEW

To review the findings of recent human studies of the association between helminth parasite infections and allergy and discuss their potential relevance to public health.

RECENT FINDINGS

Different helminth parasites may have different effects on allergy that may depend on the timing or intensity of the exposure or host genetic factors. Infections with Trichuris trichiura in early life are associated with a reduced prevalence of allergen skin test reactivity later in life and infants of helminth-infected mothers have been reported to have a reduced prevalence of eczema. Hookworm infection has been associated with a reduced prevalence of asthma in Ethiopia. Several studies have reported that anti-Ascaris IgE is an important risk factor for asthma, but this could be explained by an enhanced ability of atopics to produce IgE. Toxocara infections may be associated with an increased risk of wheeze in some populations that may be caused by the host response to the parasite or by parasite-enhanced Th2 responses to aeroallergens.

SUMMARY

Although helminth infections can modulate the host inflammatory response directed against the parasite, a causal association between helminths and atopic diseases remains uncertain.

Mucosal immunology of geohelminth infections in humans

There is limited data on the human mucosal immune response to geohelminths, but extensive data from experimental animals. Geohelminth infections may modulate mucosal immunity with effects on parasite expulsion or persistence and mucosal inflammation. Geohelminths are considered to have important effects on immunity to mucosal vaccines, infectious disease susceptibility, and anti-inflammatory effects in inflammatory bowel disease and asthma. This review will discuss the findings of studies of human immunity to geohelminths and their potential effects on non-parasite mucosal immune responses. Such effects are likely to be of public health importance in middle- and low-income countries where these parasites are endemic. There is a need for human studies on the effects of geohelminth infections on mucosal immunity and the potential for anthelmintic treatment to modify these effects. Such studies are likely to provide important insights into the regulation of mucosal immunity and inflammation, and the development of more effective mucosal vaccines.

Diet and asthma: looking back, moving forward

Asthma is an increasing global health burden, especially in the western world. Public health interventions are sought to lessen its prevalence or severity, and diet and nutrition have been identified as potential factors. With rapid changes in diet being one of the hallmarks of westernization, nutrition may play a key role in affecting the complex genetics and developmental pathophysiology of asthma. The present review investigates hypotheses about hygiene, antioxidants, lipids and other nutrients, food types and dietary patterns, breastfeeding, probiotics and intestinal microbiota, vitamin D, maternal diet, and genetics. Early hypotheses analyzed population level trends and focused on major dietary factors such as antioxidants and lipids. More recently, larger dietary patterns beyond individual nutrients have been investigated such as obesity, fast foods, and the Mediterranean diet. Despite some promising hypotheses and findings, there has been no conclusive evidence about the role of specific nutrients, food types, or dietary patterns past early childhood on asthma prevalence. However, diet has been linked to the development of the fetus and child. Breastfeeding provides immunological protection when the infant's immune system is immature and a modest protective effect against wheeze in early childhood. Moreover, maternal diet may be a significant factor in the development of the fetal airway and immune system. As asthma is a complex disease of gene-environment interactions, maternal diet may play an epigenetic role in sensitizing fetal airways to respond abnormally to environmental insults. Recent hypotheses show promise in a biological approach in which the effects of dietary factors on individual physiology and immunology are analyzed before expansion into larger population studies. Thus, collaboration is required by various groups in studying this enigma from epidemiologists to geneticists to immunologists. It is now apparent that this multidisciplinary approach is required to move forward and understand the complexity of the interaction of dietary factors and asthma.