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.

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.

Soil-transmitted helminths (STH) cause significant morbidity among children in low and middle-income countries (LMICs). We followed a birth cohort to 8 years of age in a rural area of coastal Ecuador and showed almost half acquired STH infections during childhood. The dominant STH parasites in this setting in children were Ascaris lumbricoides and Trichuris trichiura and infections peaked in frequency between 3 and 5 years of age. Risk of infection during childhood was associated with markers of marginalisation (Afro-Ecuadorian ethnicity and low educational level), household poverty (overcrowding and poor sanitation), and STH infections among other household members. There was evidence of a reduction in STH infection risk across all ages in study households over the calendar time course of this longitudinal study in parallel with improvements in living conditions, a period of economic growth, and increased government support for those living in extreme poverty. Our data indicate that targeting anthelmintic treatment at members of STH-infected households is likely to reduce the risk of infection in young children.

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).

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 (3^rd -4^th vs. 1^st - 2^nd: 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.

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.

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.

Cochlear obliteration following a translabyrinthine approach and its implications in cochlear implantation

The most frequent sequelae following a translabyrinthine approach for vestibular schwannoma resection is complete hearing loss on the affected side. Such patients could benefit from a cochlear implant, provided that two essential requisites are met before surgery: a preserved cochlear nerve and a patent cochlea to accommodate the electrode array. The goal of our study is to determine the prevalence and extent of cochlear ossification following a translabyrinthine approach. Postoperative MRI of 41 patients were retrospectively reviewed. Patients were classified according to the degree of cochlear obliteration into three groups (patent cochlea, partially obliterated cochlea and totally obliterated cochlea). The interval between surgery and the first MRI was studied as well as its relationship with the rate of cochlear ossification. At first postoperative MRI (mean interval of 20 months), 78% of patients showed some degree of cochlear ossification. Differences were found in the time interval between surgery and first MRI for each group, showing a smaller interval of time the patent cochlea group (p > 0.05). When MRI was performed before the first year after surgery, a larger rate of patent cochlea was found (p > 0.05). The present study suggests that cochlear ossification is a time-depending process, whose grounds are still to be defined.

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.

Effects of poor hygiene on cytokine phenotypes in children in the tropics

We describe immune phenotypes (innate and adaptive cytokines) according to environmental exposure using latent class analysis. A total of 310 schoolchildren living in Ecuador were assayed for spontaneous cytokine production as well as mitogen (SEB)-stimulated cytokines in whole blood cultures. We collected data on environmental exposures by questionnaire and on intestinal parasites by examination of stool samples. Latent class analysis (LCA) was used to group children according to their innate (IL-6, IL-8, IL-10 and TNF-α) and adaptive (IL-5, IL-13, IL-17, IFN-γ and IL-10) cytokine profile. We also conducted multiple-group LCA and LCA with covariates to evaluate the effect of predictors on profile membership. We identified both hyporesponsive and Th2-modified immune phenotypes produced by peripheral blood leukocytes (PBLs) that were associated with intestinal worms and birth order, providing insights into how poor hygiene mediates immunologic effects on immune-mediated diseases.

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.

Effect of urban vs. rural residence on the association between atopy and wheeze in Latin America: findings from a case-control analysis

Background

The association between atopy and asthma is attenuated in non-affluent populations, an effect that may be explained by childhood infections such as geohelminths.

Objective

To investigate the association between atopy and wheeze in schoolchildren living in urban and rural areas of Ecuador and examine the effects of geohelminths on this association.

Methods

We performed nested case–control studies among comparable populations of schoolchildren living in rural communities and urban neighbourhoods in the Province of Esmeraldas, Ecuador. We detected geohelminths in stool samples, measured recent wheeze and environmental exposures by parental questionnaire, and atopy by specific IgE (sIgE) and skin prick test (SPT) reactivity to aeroallergens.

Results

Atopy, particularly sIgE to house dust mite (HDM), was more strongly associated with recent wheeze in urban than rural schoolchildren: (urban, adj. OR 5.19, 95% CI 3.37–8.00, P < 0.0001; rural, adj. OR 1.81, 95%CI 1.09–2.99, P = 0.02; interaction, P < 0.001). The population fractions of wheeze attributable to atopy were approximately two-fold greater in urban schoolchildren: SPT to any allergen (urban 23.5% vs. rural 10.1%), SPT to HDM (urban 18.5% vs. rural 9.6%), and anti-HDM IgE (urban 26.5% vs. rural 10.5%), while anti-Ascaris IgE was related to wheeze in a high proportion of rural (49.7%) and urban (35.4%) children. The association between atopy and recent wheeze was attenuated by markers of geohelminth infections.

Conclusions

Our data suggest that urban residence modifies the association between HDM atopy and recent wheeze, and this effect is explained partly by geohelminth infections.

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.

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.

Patent human infections with the whipworm, Trichuris trichiura, are not associated with alterations in the faecal microbiota

Background

The soil-transmitted helminth (STH), Trichuris trichiura colonises the human large intestine where it may modify inflammatory responses, an effect possibly mediated through alterations in the intestinal microbiota. We hypothesised that patent T. trichiura infections would be associated with altered faecal microbiota and that anthelmintic treatment would induce a microbiota resembling more closely that observed in uninfected individuals.

Materials and Methods

School children in Ecuador were screened for STH infections and allocated to 3 groups: uninfected, T. trichiura only, and mixed infections with T. trichiura and Ascaris lumbricoides. A sample of uninfected children and those with T. trichiura infections only were given anthelmintic treatment. Bacterial community profiles in faecal samples were studied by 454 pyrosequencing of 16 S rRNA genes.

Results

Microbiota analyses of faeces were done for 97 children: 30 were uninfected, 17 were infected with T. trichiura, and 50 with T. trichiura and A. lumbricoides. Post-treatment samples were analyzed for 14 children initially infected with T. trichiura alone and for 21 uninfected children. Treatment resulted in 100% cure of STH infections. Comparisons of the microbiota at different taxonomic levels showed no statistically significant differences in composition between uninfected children and those with T. trichiura infections. We observed a decreased proportional abundance of a few bacterial genera from the Clostridia class of Firmicutes and a reduced bacterial diversity among children with mixed infections compared to the other two groups, indicating a possible specific effect of A. lumbricoides infection. Anthelmintic treatment of children with T. trichiura did not alter faecal microbiota composition.

Discussion

Our data indicate that patent human infections with T. trichiura may have no effect on faecal microbiota but that A. lumbricoides colonisation might be associated with a disturbed microbiota. Our results also catalogue the microbiota of rural Ecuadorians and indicate differences with individuals from more urban industrialised societies.

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.

A novel, multi-parallel, real-time polymerase chain reaction approach for eight gastrointestinal parasites provides improved diagnostic capabilities to resource-limited at-risk populations

Diagnosis of gastrointestinal parasites has traditionally relied on stool microscopy, which has low diagnostic sensitivity and specificity. We have developed a novel, rapid, high-throughput quantitative multi-parallel real-time polymerase chain reaction (qPCR) platform. Species-specific primers/probes were used for eight common gastrointestinal parasite pathogens: Ascaris lumbricoides, Necator americanus, Ancylostoma duodenale, Giardia lamblia, Cryptosporidium spp., Entamoeba histolytica, Trichuris trichiura, and Strongyloides stercoralis. Stool samples from 400 13-month-old children in rural Ecuador were analyzed and the qPCR was compared with a standard direct wet mount slide for stool microscopy, as were 125 8-14-year-old children before and after anthelmintic treatment. The qPCR showed higher detection rates for all parasites compared with direct microscopy, Ascaris (7.0% versus 5.5%) and for Giardia (31.5% versus 5.8%). Using an enhanced DNA extraction method, we were able to detect T. trichiura DNA. These assays will be useful to refine treatment options for affected populations, ultimately leading to better health outcomes.

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.

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.

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.

High prevalence of bacterial vaginosis in adolescent girls in a tropical area of Ecuador

Bacterial vaginosis (BV) is a common clinical syndrome, but data are scarce on the BV prevalence in tropical regions among sexually active and virgin adolescents. To estimate the prevalence of BV among adolescent girls in an Ecuadorian coastal town, girls were asked to complete a questionnaire on risk factors for BV and vaginal samples were examined. Bacterial vaginosis was present in 31.5% of 213 girls, and the prevalence was similar in self-reported virgin and sexually active girls (OR 1.06, 95% CI, 0.51-2.21, P = 0.88), although the power of this analysis was limited. The prevalence of BV was high among Ecuadorian adolescent girls, and did not appear to be associated with sexual activity.

Repeated treatments with albendazole enhance Th2 responses to Ascaris Lumbricoides, but not to aeroallergens, in children from rural communities in the Tropics

Geohelminth infections are associated with modulation of immunity to parasite antigens and aeroallergens. To investigate the possibility that this modulation is affected by anthelmintic treatment, we compared cytokine responses in children who were treated with repeated doses of albendazole over 1 year versus those in children who had were not treated. Whole-blood samples were cultured with Ascaris antigen and house dust mite and cockroach allergens, and levels of interleukin (IL)-5, IL-13, interferon-gamma, and IL-10 were measured. Anthelmintic treatment was associated with enhanced production of Th2 cytokines in response to parasite antigen but did not affect responses to aeroallergens. The data indicate that long-term treatment may be associated with increased Th2 antiparasite immunity.

Alum recovery and wastewater sludge stabilization with sulfuric acid

Coagulation-flocculation is used to remove helminth ova from wastewater intended for agricultural reuse. Nevertheless, it has the drawback of producing a large amount of sludge which together with the chemicals used to treat the wastewater increases the operating cost. This can be overcome by recovering and recycling the aluminium contained in the sludge. This paper presents how an acid recovery process was applied to an Advanced Primary Treatment (APT) sludge to partially treat it and to reduce its quantity. This is a method applied several decades ago in water sludge that has not been used in secondary wastewater sludge to recover aluminium and to inactivate microorganisms. By adding sulphuric acid to a 6%TS sludge, more than 70% of the aluminium added during the coagulation flocculation process was recovered when a pH of 2 was maintained during 30 minutes and at 300 rpm of mixing conditions. This way the sludge was reduced by 45% in volume and by 63% by mass, inactivating 5 logs of faecal coliforms and 68% of helminth ova. Due to the lower alum consumption, the operating cost of the APT is reduced by 3.78 US$/1,000 m(3).