Effect of infant viral respiratory disease on childhood asthma in a non-industrialized setting.

BACKGROUND: There are limited data from non-industrialized settings on the effects of early life viral respiratory disease on childhood respiratory illness. We followed a birth cohort in tropical Ecuador to understand how early viral respiratory disease, in the context of exposures affecting airway inflammation including ascariasis, affect wheezing illness, asthma, and rhinoconjunctivitis in later childhood. METHODS: A surveillance cohort nested within a birth cohort was monitored for respiratory infections during the first 2 years in rural Ecuador and followed for 8 years for the development of wheeze and rhinoconjunctivitis. Nasal swabs were examined for viruses by polymerase chain reaction and respiratory symptom data on recent wheeze and rhinoconjunctivitis were collected by periodic questionnaires at 3, 5, and 8 years. Stools from pregnant mothers and periodically from children aged 2 years were examined microscopically for soil-transmitted helminths. Atopy was measured by allergen skin prick testing at 2 years. Spirometry, fractional exhaled nitric oxide measurement, and nasal washes were performed at 8 years. Associations between clinically significant respiratory disease (CSRD) and wheezing or rhinoconjunctivitis at 3, 5, and 8 years were estimated using multivariable logistic regression. RESULTS: Four hundred and twenty six children were followed of which 67.7% had at least one CSRD episode; 12% had respiratory syncytial virus (RSV)+CSRD and 36% had rhinovirus (RHV)+CSRD. All-cause CSRD was associated with increased wheeze at 3 (OR 2.33 [95% confidence intervals (CI) 1.23-4.40]) and 5 (OR: 2.12 [95% CI 1.12-4.01]) years. RHV+CSRD was more strongly associated with wheeze at 3 years in STH-infected (STH-infected [OR 13.41, 95% CI 1.56-115.64] vs. uninfected [OR 1.68, 95% CI 0.73-3.84]) and SPT+ (SPT+ [OR 9.42, 95% CI 1.88-47.15] versus SPT- [OR 1.92, 95% CI 0.84-4.38]) children. No associations were observed between CSRD and rhinoconjunctivitis. DISCUSSION: CSRD was significantly associated with childhood wheeze with stronger associations observed for RHV+CSRD in SPT+ and STH-infected children.

Geometric Morphometric Analysis of Wing Shape to Identify Populations of Apis mellifera in Camagüey, Cuba.

A total of 45 Apis mellifera colonies were sampled from nine centers for rearing queens in the Camagüey province, Cuba. Wing geometric morphometric analysis was used to determine the ancestry and identify Africanization processes at different altitudes in managed honeybee populations on the island. A total of 350 reference wings were obtained from the pure subspecies: Apis mellifera mellifera, Apis mellifera carnica, Apis mellifera ligustica, Apis mellifera caucasia, Apis mellifera iberiensis, Apis mellifera intermissa, and Apis mellifera scutellata for the study. Our results showed that altitude influences wing shape; and that 96.0% (432) of the individuals were classified as Cuban hybrids, with a tendency to the formation of a new morphotype. In addition, a great similarity was found with the subspecies Apis mellifera mellifera, and it was confirmed that there is no Africanization due to the low presence of 0.44% (2) of this morphotype in the population under study. The greatest Mahalanobis distances were obtained for the comparisons between the center rearing of queens in the Camagüey province with the subspecies A. m. scutellata (D2 = 5.18); A. m. caucasia (D2 = 6.08); A. m. ligustica (D2 = 6.27); and A. m. carnica (D2 = 6.62). The well-defined pattern of wing shape produced by honeybee populations in Camagüey's centers for queen rearing suggests a Cuban hybrid. Moreover, it is essential to note that the populations of bees under investigation lack Africanized morphotypes, indicating that Camagüey bees have not interacted with the African lineage.

Understanding and controlling asthma in Latin America: A review of recent research informed by the SCAALA programme.

Asthma is an important health concern in Latin America (LA) where it is associated with variable prevalence and disease burden between countries. High prevalence and morbidity have been observed in some regions, particularly marginalized urban populations. Research over the past 10 years from LA has shown that childhood disease is primarily non-atopic. The attenuation of atopy may be explained by enhanced immune regulation induced by intense exposures to environmental factors such as childhood infections and poor environmental conditions of the urban poor. Non-atopic symptoms are associated with environmental and lifestyle factors including poor living conditions, respiratory infections, psychosocial stress, obesity, and a diet of highly processed foods. Ancestry (particularly African) and genetic factors increase asthma risk, and some of these factors may be specific to LA settings. Asthma in LA tends to be poorly controlled and depends on access to health care and medications. There is a need to improve management and access to medication through primary health care. Future research should consider the heterogeneity of asthma to identify relevant endotypes and underlying causes. The outcome of such research will need to focus on implementable strategies relevant to populations living in resource-poor settings where the disease burden is greatest.

Patterns of allergic sensitization and factors associated with emergence of sensitization in the rural tropics early in the life course: findings of an Ecuadorian birth cohort.

INTRODUCTION: There are limited data on emergence of allergic sensitization (or atopy) during childhood in tropical regions. METHODS: We followed a birth cohort of 2404 newborns to 8 years in tropical Ecuador and collected: risk factor data by maternal questionnaires periodically from birth; atopy was measured by skin prick test reactivity (SPT) to aeroallergens in parents, and aeroallergens and food allergens in children at 2, 3, 5, and 8 years; and stool samples for soil-transmitted helminths (STH) from children periodically to 8 years and from parents and household members at the time of recruitment of cohort children. Data on risk factors were measured either at birth or repeatedly (time-varying) from birth to 8 years. Longitudinal repeated-measures analyses were done using generalized estimating equations to estimate an the age-dependent risk of positive SPT (SPT+) to any allergen or mite during early childhood to school age. RESULTS: SPT+ to any allergen was present in 29.0% of fathers and 24.8% of mothers, and in cohort children increased with age, initially to mite but later to cockroach, reaching 14.8% to any allergen (10.7% mite and 5.3% cockroach) at 8 years. Maternal SPT+, particularly presence of polysensitization (OR 2.04, 95% CI 1.49-2.77) significantly increased the risk of SPT+ during childhood, while household overcrowding at birth decreased the risk (OR 0.84, 95% CI 0.72-0.98). For mite sensitization, maternal polysensitization increased (OR 2.14, 95% CI 1.40-3.27) but rural residence (OR 0.69, 95% CI 0.50-0.94) and birth order (3rd -4th vs. 1st - 2nd: OR 0.71, 95% CI 0.52-0.98) decreased the risk. Time-varying exposures to agricultural activities (OR 0.77, 95% CI 0.60-0.98) and STH parasites (OR 0.70, 95% CI 0.64-0.91) during childhood decreased while anthelmintics increased the childhood risk (OR 1.47, 95% CI 1.05-2.05) of mite sensitization. CONCLUSION: Our data showed the emergence of allergic sensitization, primarily to mite and cockroach allergens, during childhood in tropical Ecuador. A role for both antenatal and postnatal factors acting as potential determinants of SPT+ emergence was observed.

The epidemiology of soil-transmitted helminth infections in children up to 8 years of age: Findings from an Ecuadorian birth cohort.

BACKGROUND: There are few prospective longitudinal studies of soil-transmitted helminth (STH) infections during early childhood. We studied the epidemiology of and risk factors for soil-transmitted helminth infections from birth to 8 years of age in tropical Ecuador. METHODS: 2,404 newborns were followed to 8 years of age with periodic stool sample collections. Stool samples were collected also from household members at the time of the child's birth and examined by microscopy. Data on social, environmental, and demographic characteristics were collected by maternal questionnaire. Associations between potential risk factors and STH infections were estimated using generalized estimated equations applied to longitudinal binary outcomes for presence or absence of infections at collection times. RESULTS: Of 2,404 children, 1,120 (46.6%) were infected with at least one STH infection during the first 8 years of life. The risk of A. lumbricoides (16.2%) was greatest at 3 years, while risks of any STH (25.1%) and T. trichiura (16.5%) peaked at 5 years. Factors significantly associated with any STH infection in multivariable analyses included age, day-care (OR 1.34, 95% CI 1.03-1.73), maternal Afro-Ecuadorian ethnicity (non-Afro vs. Afro, OR 0.55, 95% CI 0.43-0.70) and lower educational level (secondary vs. illiterate, OR 0.31, 95% CI 0.22-0.45)), household overcrowding (OR 1.53, 95% CI 1.21-1.94)), having a latrine rather than a water closet (WC vs. latrine, OR 0.77, 95% CI 0.62-0.95)), and STH infections among household members (OR 2.03, 95% CI 1.59-2.58)). T. trichiura was more associated with poverty (high vs. low socioeconomic status, OR, 0.63, 95% CI 0.40-0.99)] and presence of infected siblings in the household (OR 3.42, 95% CI 2.24-5.22). CONCLUSION: STH infections, principally with A. lumbricoides and T. trichiura, peaked between 3 and 5 years in this cohort of children in tropical Ecuador. STH infections among household members were an important determinant of infection risk and could be targeted for control and elimination strategies.

Impact of early life geohelminths on wheeze, asthma and atopy in Ecuadorian children at 8 years.

BACKGROUND: Early-life exposures to geohelminths may protect against development of wheeze/asthma and atopy. OBJECTIVE: To study the effect of maternal geohelminths and infections in children during the first 5 years on atopy, wheeze/asthma and airways reactivity/inflammation at 8 years. METHODS: Birth cohort of 2404 neonates followed to 8 years in rural Ecuador. Data on wheeze/asthma were collected by questionnaire and atopy by skin prick test (SPT) reactivity to 9 allergens. We measured airways reactivity to bronchodilator, fractional exhaled nitric oxide (FeNO) and nasal eosinophilia. Stool samples were examined for geohelminths by microscopy. RESULTS: 1933 (80.4%) children were evaluated at 8 years. Geohelminths were detected in 45.8% of mothers and 45.5% of children to 5 years. Frequencies of outcomes at 8 years were as follows: wheeze (6.6%), asthma between 5 and 8 years (7.9%), SPT (14.7%), airways reactivity (10%) and elevated FeNO (10.3%) and nasal eosinophilia (9.2%). Any maternal geohelminth was associated with reduced SPT prevalence (OR 0.72). Childhood Trichuris trichiura infections during the first 5 years were associated with reduced wheeze (OR 0.57) but greater parasite burdens with Ascaris lumbricoides at 5 years were associated with increased wheeze (OR 2.83) and asthma (OR 2.60). Associations between maternal geohelminths and wheeze/asthma were modified by atopy. Parasite-specific effects on wheeze/asthma and airways reactivity and inflammation were observed in non-atopic children. CONCLUSIONS: Our data provide novel evidence for persistent effects of in utero geohelminth exposures on childhood atopy but highlight the complex nature of the relationship between geohelminths and the airways. Registered as an observational study (ISRCTN41239086).

Measuring urbanicity as a risk factor for childhood wheeze in a transitional area of coastal ecuador: a cross-sectional analysis.

BACKGROUND: The urbanisation process has been associated with increases in asthma prevalence, an observation supported largely by studies comparing urban with rural populations. The nature of this association remains poorly understood, likely because of the limitations of the urban-rural approach to understand what a multidimensional process is. OBJECTIVE: This study explored the relationship between the urbanisation process and asthma prevalence using a multidimensional and quantitative measure of urbanicity. METHODS: A cross-sectional analysis was conducted in 1843 children living in areas with diverse levels of urbanisation in the district of Quinindé, Ecuador in 2013-2015. Categorical principal components analysis was used to generate an urbanicity score derived from 18 indicators measured at census ward level based on data from the national census in 2010. Indicators represent demographic, socioeconomic, built environment and geographical dimensions of the urbanisation process. Geographical information system analysis was used to allocate observations and urban characteristics to census wards. Logistic random effects regression models were used to identify associations between urbanicity score, urban indicators and three widely used definitions for asthma. RESULTS: The prevalence of wheeze ever, current wheeze and doctor diagnosis of asthma was 33.3%, 13% and 6.9%, respectively. The urbanicity score ranged 0-10. Positive significant associations were observed between the urbanicity score and wheeze ever (adjusted OR=1.033, 95% CI 1.01 to 1.07, p=0.05) and doctor diagnosis (adjusted OR=1.06, 95% CI 1.02 to 1.1, p=0.001). For each point of increase in urbanicity score, the prevalence of wheeze ever and doctor diagnosis of asthma increased by 3.3% and 6%, respectively. Variables related to socioeconomic and geographical dimensions of the urbanisation process were associated with greater prevalence of wheeze/asthma outcomes. CONCLUSIONS: Even small increases in urbanicity are associated with a higher prevalence of asthma in an area undergoing the urban transition. The use of a multidimensional urbanicity indicator has greater explanatory power than the widely used urban-rural dichotomy to improve our understanding of how the process of urbanisation affects the risk of asthma.

Soil-transmitted helminth parasites and allergy: Observations from Ecuador.

There is considerable interest as to potential protective effects of soil-transmitted helminths (STH) against allergy and allergic diseases. Here, we discuss findings of studies done of the effects of STH parasites on atopy and allergic diseases in Ecuador. While cross-sectional studies have consistently shown a reduced prevalence of allergen skin prick test (SPT) reactivity among infected schoolchildren, the removal of these infections by repeated deworming did not affect SPT prevalence over the short-term (ie, 12 months) but may have increased SPT prevalence over the long-term (ie, 15-17 years). In the case of allergic symptoms, cross-sectional studies have generally not shown associations with STH and intervention studies showed no impact on prevalence. However, a birth cohort suggested that early STH infections might reduce wheeze by 5 years. Allergic sensitization to Ascaris, however, explained a significant proportion of wheezing among rural schoolchildren. Studies of the effects of STH on immune and inflammatory responses indicated a potential role of STH in contributing to more robust regulation. The effects of STH on allergy are likely to be determined by history of exposure over the life-course and by interactions with a wide variety of other infectious and non-infectious factors.

Effect of Early-Life Geohelminth Infections on the Development of Wheezing at 5 Years of Age.

RATIONALE: Exposures to geohelminths during gestation or early childhood may reduce risk of wheezing illness/asthma and atopy during childhood in tropical regions. OBJECTIVES: To investigate the effect of maternal and early childhood geohelminths on development of wheeze/asthma and atopy during the first 5 years of life. METHODS: A cohort of 2,404 neonates was followed to 5 years of age in a rural district in coastal Ecuador. Data on wheeze were collected by questionnaire and atopy was measured by allergen skin prick test reactivity to 10 allergens at 5 years. Stool samples from mothers and children were examined for geohelminths by microscopy. MEASUREMENTS AND MAIN RESULTS: A total of 2,090 (86.9%) children were evaluated at 5 years. Geohelminths were observed in 45.5% of mothers and in 34.1% of children by 3 years. Wheeze and asthma were reported for 12.6% and 5.7% of children, respectively, whereas 14.0% had skin test reactivity at 5 years. Maternal geohelminths were associated with an increased risk of wheeze (adjusted odds ratio, 1.41; 95% confidence interval, 1.06-1.88), whereas childhood geohelminths over the first 3 years of life were associated with reduced risk of wheeze (adjusted odds ratio, 0.70; 95% confidence interval, 0.52-0.96) and asthma (adjusted odds ratio, 0.60; 95% confidence interval, 0.38-0.94) but not skin prick test reactivity. The effects on wheeze/asthma were greatest with later age of first infection, were observed only in skin test-negative children, but were not associated with parasite burden or specific geohelminths. CONCLUSIONS: Although maternal exposures to geohelminths may increase childhood wheeze, childhood geohelminths during the first 3 years may provide protection through a nonallergic mechanism. Registered as an observational study (ISRCTN41239086).

Associations between infant fungal and bacterial dysbiosis and childhood atopic wheeze in a nonindustrialized setting.

BACKGROUND: Asthma is the most prevalent chronic disease of childhood. Recently, we identified a critical window early in the life of both mice and Canadian infants during which gut microbial changes (dysbiosis) affect asthma development. Given geographic differences in human gut microbiota worldwide, we studied the effects of gut microbial dysbiosis on atopic wheeze in a population living in a distinct developing world environment. OBJECTIVE: We sought to determine whether microbial alterations in early infancy are associated with the development of atopic wheeze in a nonindustrialized setting. METHODS: We conducted a case-control study nested within a birth cohort from rural Ecuador in which we identified 27 children with atopic wheeze and 70 healthy control subjects at 5 years of age. We analyzed bacterial and eukaryotic gut microbiota in stool samples collected at 3 months of age using 16S and 18S sequencing. Bacterial metagenomes were predicted from 16S rRNA data by using Phylogenetic Investigation of Communities by Reconstruction of Unobserved States and categorized by function with Kyoto Encyclopedia of Genes and Genomes ontology. Concentrations of fecal short-chain fatty acids were determined by using gas chromatography. RESULTS: As previously observed in Canadian infants, microbial dysbiosis at 3 months of age was associated with later development of atopic wheeze. However, the dysbiosis in Ecuadorian babies involved different bacterial taxa, was more pronounced, and also involved several fungal taxa. Predicted metagenomic analysis emphasized significant dysbiosis-associated differences in genes involved in carbohydrate and taurine metabolism. Levels of the fecal short-chain fatty acids acetate and caproate were reduced and increased, respectively, in the 3-month stool samples of children who went on to have atopic wheeze. CONCLUSIONS: Our findings support the importance of fungal and bacterial microbiota during the first 100 days of life on the development of atopic wheeze and provide additional support for considering modulation of the gut microbiome as a primary asthma prevention strategy.

Rural to urban migration is associated with increased prevalence of childhood wheeze in a Latin-American city.

INTRODUCTION: The urbanisation process has been associated with increases in asthma prevalence in urban and rural areas of low-income and middle-income countries (LMICs). However, although rural to urban migration and migration between cities are considered important determinants of this process, few studies have evaluated the effects of internal migration on asthma in urban populations of LMICs. The present study evaluated the effects of internal migration on the prevalence of wheeze in an urban area of Latin America. METHODS: We did a cross-sectional analysis of 2510 schoolchildren living in the city of Esmeraldas, Ecuador. Logistic regression was used to analyse associations between childhood wheeze and different aspects of migration among schoolchildren. RESULTS: 31% of schoolchildren were migrants. Rural to urban migrants had a higher prevalence of wheeze, (adj.OR=2.01,95% CI1.30 to 3.01, p=0.001) compared with non-migrants. Age of migration and time since migration were associated with wheeze only for rural to urban migrants but not for urban to urban migrants. Children who had migrated after 3 years of age had a greater risk of wheeze (OR 2.51, 95% CI 1.56 to 3.97, p=0.001) than non-migrants while migrants with less than 5 years living in the new residence had a higher prevalence of wheeze than non-migrants (<3 years: OR=2.34, 95% CI 1.26 to 4.33, p<0.007 and 3-5 years: OR=3.03, 95% CI 1.49 to 6.15, p<0.002). CONCLUSIONS: Our study provides evidence that rural to urban migration is associated with an increase in the prevalence of wheeze among schoolchildren living in a Latin-American city. Age of migration and time since migration were important determinants of wheeze only among migrants from rural areas. A better understanding of the social and environmental effects of internal migration could improve our understanding of the causes of the increase in asthma and differences in prevalence between urban and rural populations.

Comparison of Cytokine Responses in Ecuadorian Children Infected with Giardia, Ascaris, or Both Parasites.

AbstractMore than 2 billion people are infected with parasites globally, and the majority have coinfections. Intestinal protozoa and helminths induce polarizing CD4+ T-helper cell 1 (Th1) mediated cytokine responses within the host. Such immune polarization may inhibit the ability of the host to mount an adequate immune response for pathogen clearance to concurrent pathogens. The current study evaluated the plasma cytokine profile in Ascaris and Giardia coinfected children compared with Giardia- and Ascaris-only infected children. Fecal samples and blood samples were collected from asymptomatic 3-year-old children living in the district of Quininde, Ecuador. Stool samples that tested positive for Giardia lamblia-only, Ascaris lumbricoides-only, or G. lamblia and A. lumbricoides coinfections were confirmed by quantitative real-time polymerase chain reaction. Plasma samples from the study subjects were used to quantitate cytokines. A total of 39 patients were evaluated. Children with coinfection had a significant decrease in Th1 cytokine production, interleukin 2 (IL-2) (P < 0.05), IL-12 (P < 0.05), and tumor necrosis factor alpha (P < 0.05) compared with Giardia-only infected children. Coinfected children had an increase in IL-10/interferon gamma (IFN-γ) ratio compared with uninfected (P < 0.05) and Ascaris alone (P < 0.05). The increased IL-10/IFN-γ ratio in the setting of decreased Th1 cytokine response indicates Th2 polarization in the coinfected group. Reduced Th1 cytokines in children coinfected with Ascaris and Giardia may impair the host's ability to eradicate Giardia infection leading to chronic giardiasis.

Maternal Helminth Infection Is Associated With Higher Infant Immunoglobulin A Titers to Antigen in Orally Administered Vaccines.

BACKGROUND: Many studies have documented lower vaccine efficacy among children in low-income countries, compared with their counterparts in high-income countries. This disparity is especially apparent with respect to oral vaccines such as rotavirus and oral polio vaccines. One potential contributing factor is the presence of maternal antenatal helminth infections, which can modulate the infant's developing immune system. METHODS: Using a multiplex immunoassay, we tested plasma immunoglobulin A (IgA) or immunoglobulin G (IgG) levels specific for antigens in 9 routinely administered childhood vaccines among 1639 children aged approximately 13 months enrolled in the ECUAVIDA (Ecuador Life) birth cohort study in Ecuador. We compared vaccine responses in 712 children of mothers who tested positive for helminth infections in the last trimester of pregnancy to responses in 927 children of mothers without helminth infection. RESULTS: Plasma IgA levels specific for antigens in rotavirus vaccine and oral polio vaccine containing poliovirus serotypes 1 and 3 were all significantly higher in children of helminth-infected mothers, compared with children of uninfected mothers. Plasma IgG levels specific for diphtheria, tetanus, pertussis, measles, rubella, and Haemophilus influenzae type b vaccine antigens were comparable between the 2 groups. CONCLUSIONS: Antenatal maternal helminth infections were not associated with reduced antibody responses to infant vaccines, but rather with modestly increased IgA responses to oral vaccines.

Effects of maternal geohelminth infections on allergy in early childhood.

BACKGROUND: Maternal geohelminth infections during pregnancy may protect against allergy development in childhood. OBJECTIVE: We sought to investigate the effect of maternal geohelminths on the development of eczema, wheeze, and atopy during the first 3 years of life. METHODS: A cohort of 2404 neonates was followed to 3 years of age in a rural district in coastal Ecuador. Data on wheeze and eczema were collected by means of questionnaire and physical examination at 13, 24, and 36 months of age. Atopy was measured based on skin prick test (SPT) reactivity to 9 allergens at 36 months. Maternal stool samples were examined for geohelminths by microscopy. Data on potential confounders was collected after birth by questionnaire. RESULTS: Geohelminths were observed in 45.9% of mothers. Eczema and wheeze were reported for 17.7% and 25.9%, respectively, of 2069 (86.1%) children with complete follow-up to 3 years, and allergen SPT reactivity to any allergen was present in 17.2% and to house dust mite in 8.7%. Maternal geohelminth infections were not significantly associated with eczema (adjusted odds ratio [OR], 1.26; 95% CI, 0.98-1.61), wheeze (adjusted OR, 1.02; 95% CI, 0.82-1.27), and SPT reactivity to any allergen (adjusted OR, 0.79; 95% CI, 0.61-1.01). In subgroup analyses maternal geohelminths were associated with a significantly reduced risk of SPT reactivity to mite and other perennial allergens, and maternal ascariasis was associated with an increased risk of eczema and reduced risk of SPT reactivity to all allergens. CONCLUSION: Our data do not support a protective effect of maternal infections with geohelminth parasites during pregnancy against the development of eczema and wheeze in early childhood, although there was evidence in subgroup analyses for a reduction in SPT reactivity to house dust mites and perennial allergens.

Effects of environment on human cytokine responses during childhood in the tropics: role of urban versus rural residence.

BACKGROUND: Environment may have a key role in the development of the immune system in childhood and environmental exposures associated with rural residence may explain the low prevalence of allergic and autoimmune diseases in the rural tropics. We investigated the effects of urban versus rural residence on the adaptive immune response in children living in urban and rural areas in a tropical region of Latin America. METHODS: We recruited school children in either rural communities in the Province of Esmeraldas or in urban neighborhoods in the city of Esmeraldas, Ecuador. We collected data on environmental exposures by questionnaire and on intestinal parasites by examination of stool samples. Peripheral blood leukocytes (PBLs) in whole blood were stimulated with superantigen, parasite antigens and aeroallergens and IFN-γ, IL-5, IL-10, IL-13, and IL-17 were measured in supernatants. RESULTS: We evaluated 440 school children; 210 living in rural communities and 230 in the city of Esmeraldas. Overall, urban children had greater access to piped water (urban 98.7 % vs. rural 1.9 %), were more likely to have a household bathroom (urban 97.4 % vs. rural 54.8 %), and were less likely to be infected with soil-transmitted helminth infections (urban 20.9 % vs. rural 73.5 %). Generally, detectable levels of cytokines were more frequent in blood from children living in urban than rural areas. Urban residence was associated with a significantly greater frequency of IL-10 production spontaneously (adjusted OR 2.56, 95 % CI 1.05-6.24) and on stimulation with Ascaris (adj. OR 2.5, 95 % CI 1.09-5.79) and house dust mite (adj. 2.24, 95 % CI 1.07-4.70) antigens. Analysis of effects of environmental exposures on SEB-induced IL-10 production within urban and rural populations showed that some environmental exposures indicative of poor hygiene (urban - higher birth order, A. lumbricoides infection; rural - no bathroom, more peri-domiciliary animals, and living in a wood/bamboo house) were associated with elevated IL-10. CONCLUSIONS: In our study population, the immune response of children living in an urban environment was associated more frequently with the production of the immune regulatory cytokine, IL-10. Some factors related to poor hygiene and living conditions were associated with elevated IL-10 production within urban and rural populations.

Risk factors for acute asthma in tropical America: a case-control study in the City of Esmeraldas, Ecuador.

BACKGROUND: Despite the high asthma rates described in Latin America, asthma risk factors in poor urban settings are not well established. We investigated risk factors for acute asthma among Ecuadorian children. METHODS: A matched case-control study was carried out in a public hospital serving a coastal city. Children with acute asthma were age- and sex-matched to non-asthmatics. A questionnaire was administered, and blood, as well as stool, and nasopharyngeal swabs were collected. RESULTS: Sixty cases and 119 controls aged 5-15 were evaluated. High proportions of cases were atopic with population-attributable fractions for atopy of 68.5% for sIgE and 57.2% for SPT. Acute asthma risk increased with greater titers of mite IgE (3.51-50 kU/l vs. <0.70kU/l - OR 4.56, 95% CI 1.48-14.06, p = 0.008; >50kU/l vs. <0.70kU/l - OR 41.98, 95% CI: 8.97-196.39, p < 0.001). Asthma risk was significantly independently associated with bronchiolitis (adj. OR: 38.9, 95% CI 3.26-465), parental educational level (adj. OR 1.26, 95% CI: 1.08-1.46), and presence of sIgE (adj. OR: 36.7, 95% CI: 4.00-337), while a reduced risk was associated with current contact with pets (adj. OR: 0.07, 95% CI: 0.01-0.56). Rhinovirus infection was more frequent in cases (cases 35.6% vs. controls 7.8%, p = 0.002). None of the cases were on maintenance therapy with inhaled corticosteroids and most relied on emergency department for control. CONCLUSIONS: A high proportion of children presenting to a public hospital with acute asthma were allergic to mite, particularly at high IgE titer. Poor asthma control resulted in overuse of emergency care.

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.

Norovirus Infection and Disease in an Ecuadorian Birth Cohort: Association of Certain Norovirus Genotypes With Host FUT2 Secretor Status.

BACKGROUND: Although norovirus is the most common cause of gastroenteritis, there are few data on the community incidence of infection/disease or the patterns of acquired immunity or innate resistance to norovirus. METHODS: We followed a community-based birth cohort of 194 children in Ecuador with the aim to estimate (1) the incidence of norovirus gastroenteritis from birth to age 3 years, (2) the protective effect of norovirus infection against subsequent infection/disease, and (3) the association of infection and disease with FUT2 secretor status. RESULTS: Over the 3-year period, we detected a mean of 2.26 diarrheal episodes per child (range, 0-12 episodes). Norovirus was detected in 260 samples (18%) but was not found more frequently in diarrheal samples (79 of 438 [18%]), compared with diarrhea-free samples (181 of 1016 [18%]; P = .919). A total of 66% of children had at least 1 norovirus infection during the first 3 years of life, and 40% of children had 2 infections. Previous norovirus infections were not associated with the risk of subsequent infection. All genogroup II, genotype 4 (GII.4) infections were among secretor-positive children (P < .001), but higher rates of non-GII.4 infections were found in secretor-negative children (relative risk, 0.56; P = .029). CONCLUSIONS: GII.4 infections were uniquely detected in secretor-positive children, while non-GII.4 infections were more often found in secretor-negative children.

Hygiene, atopy and wheeze-eczema-rhinitis symptoms in schoolchildren from urban and rural Ecuador.

BACKGROUND: Rural residence is protective against atopy and wheeze-rhinitis-eczema symptoms in developed countries, an effect attributed to farming and poor hygiene exposures. There are few data from developing countries addressing this question. We compared atopy and wheeze-rhinitis-eczema symptoms between urban and rural Ecuador, and explored the effects of farming and poor hygiene exposures. METHODS: We performed cross sectional studies of schoolchildren living in rural and urban Ecuador. Data on symptoms and farming/hygiene exposures were collected by parental questionnaire, atopy by allergen skin prick test reactivity and geohelminth infections by stool examinations. RESULTS: Among 2526 urban and 4295 rural schoolchildren, prevalence was: atopy (10.0% vs 12.5%, p=0.06), wheeze (9.4% vs 10.1%, p=0.05), rhinitis (8.1% vs 6.4%, p=0.02) and eczema (5.9% vs 4.7%, p=0.06). A small proportion of symptoms were attributable to atopy (range 3.9-10.7%) with greater attributable fractions for respiratory symptoms observed in urban schoolchildren. Respiratory symptoms were associated with poor hygiene/farming exposures: wheeze with lack of access to potable water; and rhinitis with household pets, no bathroom facilities and contact with large farm animals. Birth order was inversely associated with respiratory symptoms. Area of residence and atopy had few effects on these associations. CONCLUSIONS: Urban schoolchildren living in Ecuador have a similar prevalence of atopy, eczema and wheeze but a higher prevalence of rhinitis compared with rural children. Some farming and poor hygiene exposures were associated with an increase in the prevalence of wheeze or rhinitis while birth order was inversely associated with these symptoms.