Bronchial hyper-responsiveness and atopy in urban, peri-urban and rural South African children

Environmental exposures associated with atopy in a rural community in Gwanda district, Zimbabwe: a cross-sectional study

Introduction

The increasing prevalence of allergic diseases in Zimbabwe may be attributed to changing environmental exposure patterns. In this study, we sought to identify the most influential environmental and lifestyle factors that may explain the observed atopy in a rural community in Zimbabwe.

Methods

Using a cross-sectional study, information on a wide array of environmental and lifestyle exposures was self-reported by a sample of participants (children aged <18 years and adults aged ≥18 years) in the Gwanda district, Zimbabwe. To consenting participants, we performed skin prick testing (SPT) at a local clinic in Gwanda district to identify atopic individuals. Variables with a p value <0.25 from univariate analysis were included in backward-elimination multiple logistic regression analysis. Separate regression analyses were conducted for children (n = 108), adults (n = 388), and a subgroup of adults who reported ever being employed in any potentially harmful occupation (n = 153).

Results

Compared with boys, girls were more likely to be sensitised to at least one allergen (OR = 4.87, 95% CI = 1.22-19.51). Among adults, the likelihood of sensitisation increased with increasing age (OR = 1.02, 95% CI = 1.01-1.03) and with a history of bloody urine and/or schistosomiasis (OR = 2.20, 95% CI = 0.98-4.95). In the subgroup of adults who reported ever being employed in any potentially harmful occupation, atopic sensitisation was associated with a history of tuberculosis (TB; OR = 3.37, 95% CI = 1.08-10.52) and a history of bloody urine and/or schistosomiasis (OR = 4.36, 95% CI = 1.40-13.65). Other notable, though not significant, factors were passive or parental smoking, alcohol consumption, indoor dampness and visible mould on walls.

Conclusion

Girls were more likely to be sensitised to at least one allergen when compared to boys. Among adults, atopic sensitisation was positively associated with age, parental smoking, alcohol consumption and history of bloody urine or schistosomiasis but negatively associated with indoor cooking. A history of TB or helminth infection increased the likelihood of atopy among adults with history of employment. Longitudinal studies to explore the temporal and causal relationships between these factors and allergic outcomes are essential. There is a need for early public health interventions to address environmental and lifestyle factors for the prevention and control of allergic diseases in African rural communities.

Sensitisation to Imbrasia belina (mopane worm) and other local allergens in rural Gwanda district of Zimbabwe

Background

The prevalence of allergic diseases is increasing in Zimbabwe and the data relate to local as well as exotic allergen sources. As entomophagy, the practice of eating insects, is a recognised source of local allergens, we sought to measure the prevalence of and risk factors for sensitisation to Imbrasia belina (mopane worm), a popular edible insect. This was investigated alongside other locally relevant allergens in a rural community in Gwanda district, south of Zimbabwe.

Methods

A cross sectional study was conducted among 496 adults and children aged 10 years and above in Gwanda district, a mopane worm harvesting area in Zimbabwe. Data on individual characteristics and mopane worm exposure factors were collected using questionnaires. Sensitivity to allergens was assessed by performing skin prick tests at a local clinic using 10 different commercial allergen extracts (Stallergenes, France) and in-house extracts of mopane worm (Imbrasia belina) and mopane leaves (Colophospermum mopane). Data were analysed using Stata version 13 software.

Results

The prevalence of sensitisation to at least one allergen was 31.17% (n = 144). The prevalence of atopy was higher in adults (33.33%) than in children (23.53%) (p = 0.059). The commonest inhalant allergen sources were mopane worm (14.29%), Tyrophagus putrescentiae (14.29%), mopane leaves (13.42%), Alternaria alternata (6.49%) and Dermatophagoides pteronyssinus (6.49%). Polysensitisation was demonstrated in the study population and of the 108 participants (75%) who were sensitised to two or more allergens, 66 (61%) were women. Sensitisation to mopane worm and mopane leaves often clustered with Tyrophagus putrescentiae amongst adults. Adjusted logistic regression analyses between mopane worm sensitisation and self-reported exposure variables showed that sensitisation was more likely amongst mopane worm harvesters (OR = 1.92, 95%CI = 0.77–4.79), those who cooked or roasted mopane worms during harvesting (OR = 2.69, 95%CI = 0.78–9.31) and harvesting without personal protective equipment (PPE) (OR = 2.12, 95%CI = 0.83–5.44) compared to non-harvesters.

Conclusion

Atopic sensitization was common in this mopane worm harvesting community in Gwanda district of Zimbabwe. There was frequent co-sensitisation of mopane worm and mopane leaves with Tyrophagus putrescentiae in children and adults. It is important to determine the clinical relevance of our findings, particularly relating to mopane worm sensitisation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13223-022-00668-0.

Association between allergic sensitization and intestinal parasite infection in schoolchildren in Gqeberha, South Africa

Background

Inconsistent data exist regarding the influence of parasitic infection on the prevalence of allergic sensitization and disorders.

Objective

To investigate the impact of geohelminth and protozoan infections on sensitization patterns and allergic symptoms of children living in low‐income communities in Gqeberha, South Africa.

Methods

In a cross‐sectional study, 587 schoolchildren aged 8–12 years were recruited in June 2016 and screened for reactivity to common allergens by skin prick tests (SPTs) and for parasitic infections by stool examination. Additionally, questionnaires were completed to record allergic symptoms the children may have experienced.

Results

Positive SPTs were found in 237/587 children (40.4%), and about one‐third of whom were polysensitized. Sensitizations were most frequently detected against the house dust mites (HDM) Dermatophagoides spp. (31.9%) and Blomia tropicalis (21.0%). Infections with geohelminths (Ascaris lumbricoides, Trichuris trichiura) were found in 26.8% and protozoan infections (Giardia intestinalis, Cryptosporidia spp.) in 13.9% of study participants. Mixed logistic regression analyses revealed negative associations between parasite infection and sensitization to Blomia tropicalis (OR: 0.54, 95% CI 0.33–0.89) and to Dermatophagoides spp. (OR 0.65, 95% CI 0.43–0.96), and between protozoan infection and allergic sensitization to any aeroallergen, although these associations were not significant when adjusted for false discovery. Geohelminth infection and intensity of geohelminth infection were both associated with reduced risk of polysensitization (OR 0.41, 95% CI 0.21–0.86), and this association remained significant with adjustment for false discovery. Reported respiratory symptoms were associated with HDM sensitization (ORs from 1.54 to 2.48), but not with parasite infection.

Conclusions and clinical relevance

Our data suggest that geohelminth infection and high geohelminth infection intensity are associated with a reduced risk of polysensitization.

Epidemiology and management of asthma and atopic dermatitis in Sub-Saharan Africa

Sub-Saharan Africa (SSA) is currently undergoing a transformation process of unprecedented magnitude owing to economic development and urbanization. This process is paralleled by a dramatic increase in prevalence and incidence of noncommunicable diseases. In this article we analyze the current situation with regard to 1 group of the earliest noncommunicable diseases in a person's life, namely, allergies and asthma. This article provides an update on the epidemiology, availability, and access to management strategies by patients experiencing bronchial asthma or atopic dermatitis in SSA. Despite all of the progress, there is still a tremendous need to support education and training, transfer of resources, and cooperation with pharmaceutical and diagnostic companies to achieve adequate treatment and sustainability in SSA with regard to allergy, asthma, and eczema management.

Asthma in South African adolescents: a time trend and risk factor analysis over two decades

Background

South Africa has undergone major economic and health system changes, impacting the epidemiology of childhood asthma. This study aimed to investigate prevalence time trends of asthma in South African adolescents over two decades and to identify associated risk factors.

Methods

A cross-sectional survey was conducted in 2017, in a randomised sample of 13–14-year-old Cape Town adolescents, using the standardised Global Asthma Network written, video and environmental questionnaires. Using time-trend analysis, the prevalence and severity of asthma were compared with data from the 2002 ISAAC phase III study. Environmental and social risk factors were analysed.

Results

A total of 3979 adolescents were included. The prevalence of lifetime and current asthma were 34.5% and 21.3%, respectively, on the self-report written questionnaire, similar to 2002 results. The prevalence of severe asthma in the previous 12 months increased, measured by wheeze limiting speech (7.8% to 11.8%), four or more attacks of wheezing (5.0% to 5.8%) or woken by wheeze on one or more nights per week (5.0% to 6.9%). The video questionnaire revealed increases in lifetime (16.9% to 22.5%), current (11.2% to 18.7%) and severe asthma (12.1% to 14.8%). Multivariate analysis showed associations between current asthma and smoking, female sex, pet exposure and higher socioeconomic status. Severe asthma was associated with smoking, pet exposure, outdoor pollution exposure and informal housing; 33% of those with severe or current asthma had been diagnosed.

Conclusion

The prevalence of asthma is high, with increasing rates of severe asthma in adolescents. Underdiagnosis is a major concern and reduction in exposure to environmental factors, particularly smoking, and improved socioeconomic development are needed.

Among South African adolescents, the prevalence of asthma is high, with increasing rates of severe asthma from 1995 to 2017. Smoking, poor living conditions and exposure to pets or air pollution are risk factors. Underdiagnosis is a major concern.https://bit.ly/3l71DKy

Sensitisation to aeroallergens in relation to asthma and other allergic diseases in Angolan children: a cross-sectional study

INTRODUCTION AND OBJECTIVES

In Africa, few studies of sensitisation profiles have been performed in children or adolescents and, in Angola, there are none. The objectives of the present study were to assess the sensitisation profile of Angolan schoolchildren and to determine the relationship between that pattern, sociodemographic factors, asthma and other allergic diseases.

MATERIALS AND METHODS

Cross-sectional, observational study in 5-14-year-old children, performed between September and November 2017, in the Province of Bengo, Angola. Five schools (15%) were randomly selected in the geographical area of the study: three from an urban area, and two from a rural area. Data were collected using the Portuguese versions of the ISAAC questionnaires for children and adolescents, regarding asthma, rhinitis and eczema. Skin prick tests (SPT) were performed with a battery of 12 aeroallergens. Stools were assessed for the presence of helminths. Descriptive statistics were used, as well as univariate calculation of odds ratios.

RESULTS

Sensitisation to aeroallergens was low (8%) and most sensitised children were asymptomatic. Most frequent sensitisations involved house dust mites, cockroach or fungi, and a high proportion of children (78.1%) were monosensitised. No relationship was detected between sensitisations and asthma, rhinitis or eczema. Place of residence, gender, age or helminthic infection did not affect the probability of having positive SPTs.

CONCLUSIONS

The most frequent sensitisations in children from Bengo Province in Angola involve house dust mites, followed by cockroach and fungi. No relationship was found between atopic sensitisation and asthma or other allergic diseases.

Urbanisation and asthma in low-income and middle-income countries: a systematic review of the urban-rural differences in asthma prevalence

BACKGROUND

Urbanisation has been associated with temporal and geographical differences in asthma prevalence in low-income and middle-income countries (LMICs). However, little is known of the mechanisms by which urbanisation and asthma are associated, perhaps explained by the methodological approaches used to assess the urbanisation-asthma relationship.

OBJECTIVE

This review evaluated how epidemiological studies have assessed the relationship between asthma and urbanisation in LMICs, and explored urban/rural differences in asthma prevalence.

METHODS

Asthma studies comparing urban/rural areas, comparing cities and examining intraurban variation were assessed for eligibility. Included publications were evaluated for methodological quality and pooled OR were calculated to indicate the risk of asthma in urban over rural areas.

RESULTS

Seventy articles were included in our analysis. Sixty-three compared asthma prevalence between urban and rural areas, five compared asthma prevalence between cities and two examined intraurban variation in asthma prevalence. Urban residence was associated with a higher prevalence of asthma, regardless of asthma definition: current-wheeze OR:1.46 (95% CI:1.22 to 1.74), doctor diagnosis OR:1.89 (95% CI:1.47 to 2.41), wheeze-ever OR:1.44 (95% CI:1.15 to 1.81), self-reported asthma OR:1.77 (95% CI:1.33 to 2.35), asthma questionnaire OR:1.52 (95% CI:1.06 to 2.16) and exercise challenge OR:1.96 (95% CI:1.32 to 2.91).

CONCLUSIONS

Most evidence for the relationship between urbanisation and asthma in LMICs comes from studies comparing urban and rural areas. These studies tend to show a greater prevalence of asthma in urban compared to rural populations. However, these studies have been unable to identify which specific characteristics of the urbanisation process may be responsible. An approach to understand how different dimensions of urbanisation, using contextual household and individual indicators, is needed for a better understanding of how urbanisation affects asthma.

PROSPERO REGISTRATION NUMBER

CRD42017064470.

Nutrition and allergic diseases in urban and rural communities from the South African Food Allergy cohort

This study describes and compares allergic diseases and sensitization in urban and rural children in the SAFFA study cohort as well as infant feeding patterns and nutritional status. We assessed the relationship between nutritional status, breastfeeding, complementary feeding patterns, and atopic diseases including aeroallergen and food allergen sensitization, self-reported atopic dermatitis, allergic rhinitis, asthma, and challenge-proven food allergy (FA).

METHODOLOGY

A total of 1185 urban and 398 rural toddlers aged 12-36 months were screened for food sensitization (FS) and FA using skin prick testing and oral food challenges. Of these, 535 and 347, respectively, were additionally screened for aeroallergen sensitization. Information was collected on infant feeding practices, and anthropometric measurements and clinical signs for atopy were documented.

RESULTS

Markedly higher rates of allergy (asthma 9.0% vs 1.0%, eczema 25.6% vs 2.0%, rhinitis 25.3% vs 3.3%, and FA 2.5% vs 0.5%) exist in urban vs rural children. 13.1% unselected urban South African children were sensitized to aeroallergens compared to 3.8% of their rural counterparts and 9.0% to any food compared to 0.5%. Exclusive breastfeeding duration was longer, and there was a later introduction of allergenic foods in rural communities. Obesity rates were similar between the two groups, but rural children were more likely to be stunted. Being overweight was associated with asthma in urban but not rural settings. In the urban cohort, children with FS and allergy were thinner than their peers.

CONCLUSION

Allergy and sensitization rates are significantly higher in unselected urban South African toddlers than their rural counterparts. Risk and protective factors for allergy and atopy may differ between urban and rural settings.

21st century research in urban WASH and health in sub-Saharan Africa: methods and outcomes in transition

Tackling global inequalities in access to Water, Sanitation and Hygiene (WASH) remains an urgent issue - 58% of annual diarrhoeal deaths are caused by inadequate WASH provision. A global context of increasing urbanisation, changing demographics and health transitions demands an understanding and impact of WASH on a broad set of health outcomes. We examine the literature, in terms of health outcomes, considering WASH access and interventions in urban sub-Saharan Africa from 2000 to 2017. Our review of studies which evaluate the effectiveness of specific WASH interventions, reveals an emphasis of WASH research on acute communicable diseases, particularly diarrhoeal diseases. In contrast, chronic communicable and non-communicable health outcomes were notable gaps in the literature as well as a lack of focus on cross-cutting issues, such as ageing, well-being and gender equality. We recommend a broader focus of WASH research and interventions in urban Africa to better reflect the demographic and health transitions happening. Abbreviations: CBA: Controlled Before and After; GSD: Government Service Delivery; IWDSSD: International Drinking-Water, Supply and Sanitation Decade (IDWSSD); KAP: Knowledge, Attitudes and Practices; IBD: Irritable Bowel Diseases; MDG: Millennium Development Goals; NTD: Neglected Tropical Diseases; PSSD: Private Sector Service Delivery; SDG: Sustainable Development Goals; SSA: Sub Saharan Africa; SODIS: Solar Disinfection System; STH: Soil Transmitted Helminths; RCT: Randomised Control Trial; WASH: Water Sanitation and Hygiene; WHO: World Health Organization.

Asthma-related outcomes associated with indoor air pollutants among schoolchildren from four informal settlements in two municipalities in the Western Cape Province of South Africa

The health impact of indoor air pollution in informal settlement households has not been extensively studied in South Africa. This cross-sectional study investigated the association between asthma and common indoor exposures among schoolchildren from four informal settlements located in two municipalities in the Western Cape Province. A total of 590 children, aged 9-11 years, were recruited. The International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire was administered to caregivers. Pulmonary function assessment included spirometry and fractional exhaled nitric oxide (FeNO). Phadiatop test for atopy was done. The prevalence of doctor-diagnosed asthma was 3.4% (n = 20) among whom only 50% were on treatment. The prevalence of current wheeze was 12.9%, and 17.6% had airway obstruction (FEV₁  < lower limit of normal), while 10.2% had airway inflammation (FeNO > 35 ppb). In adjusted logistic regression models, dampness, visible mold growth, paraffin use for cooking, and passive smoking were associated with a twofold to threefold increased risk in upper and lower airway outcomes. The strongest association was that of visible mold growth with rhinitis (adjusted odds ratio-aOR 3.37, 95% CI: 1.69-6.71). Thus, there is a need for improved diagnosis of childhood asthma and Indoor Air Quality in informal settlement households.

Association between pro-inflammatory alleles and allergic phenotypes in Xhosa adolescents

BACKGROUND

Significant differences exist in the prevalence, spectrum, and severity of allergic diseases between developing and developed countries and between subpopulations within single countries. These discrepancies likely result from a complex interaction between genetic and environmental factors. However, the precise nature of the contribution of ethnicity to genetic differences in the predisposition to allergic disease is not yet fully understood. In particular, there is a paucity of literature regarding the genetic determinants of allergic disease in people of black African origin with little or no genetic admixture.

OBJECTIVE

We aimed to analyze associations between 27 single nucleotide polymorphisms (SNPs) and allergy phenotypes in the local Xhosa population.

METHODS

A convenience sample of 213 Xhosa teenagers was enrolled at a local high school. Phenotypic data were collected in the form of a symptom questionnaire, skin prick tests for common food and aeroallergens, total serum IgE, and IgE to Ascaris lumbricoides. In addition, genotyping was performed to establish the prevalence of putative pro-inflammatory alleles.

RESULTS

We demonstrated several significant associations between polymorphisms and allergy phenotypes. In particular, 2 polymorphisms in the IL-10 gene (IL10 -592A>C and IL10 -1082A>G) and 1 in the IL-4 gene (IL4 -589C>T) showed multiple associations with allergic sensitization and asthma phenotypes. Other polymorphisms, across a multitude of genes with discrepant functions, showed less consistent associations.

CONCLUSION

This study represents an important first step in genotype/phenotype association in this population. Further research is required to confirm or refute our findings.

Application of SCM with Bayesian B-Spline to Spatio-Temporal Analysis of Hypertension in China

Most previous research on the disparities of hypertension risk has neither simultaneously explored the spatio-temporal disparities nor considered the spatial information contained in the samples, thus the estimated results may be unreliable. Our study was based on the China Health and Nutrition Survey (CHNS), including residents over 12 years old in seven provinces from 1991 to 2011. Bayesian B-spline was used in the extended shared component model (SCM) for fitting temporal-related variation to explore spatio-temporal distribution in the odds ratio (OR) of hypertension, reveal gender variation, and explore latent risk factors. Our results revealed that the prevalence of hypertension increased from 14.09% in 1991 to 32.37% in 2011, with men experiencing a more obvious change than women. From a spatial perspective, a standardized prevalence ratio (SPR) remaining at a high level was found in Henan and Shandong for both men and women. Meanwhile, before 1997, the temporal distribution of hypertension risk for both men and women remained low. After that, notably since 2004, the OR of hypertension in each province increased to a relatively high level, especially in Northern China. Notably, the OR of hypertension in Shandong and Jiangsu, which was over 1.2, continuously stood out after 2004 for males, while that in Shandong and Guangxi was relatively high for females. The findings suggested that obvious spatial-temporal patterns for hypertension exist in the regions under research and this pattern was quite different between men and women.

A prospective cohort study on ambient air pollution and respiratory morbidities including childhood asthma in adolescents from the western Cape Province: study protocol

BACKGROUND

There is evidence from existing literature that ambient air pollutant exposure in early childhood likely plays an important role in asthma exacerbation and other respiratory symptoms, with greater effect among asthmatic children. However, there is inconclusive evidence on the role of ambient air pollutant exposures in relation to increasing asthma prevalence as well as asthma induction in children. At the population level, little is known about the potential synergistic effects between pollen allergens and air pollutants since this type of association poses challenges in uncontrolled real life settings. In particular, data from sub-Sahara Africa is scarce and virtually absent among populations residing in informal residential settlements.

METHODS/DESIGN

A prospective cohort study of 600 school children residing in four informal settlement areas with varying potential ambient air pollutant exposure levels in the Western Cape in South Africa is carried-out. The study has two follow-up periods of at least six-months apart including an embedded panel study in summer and winter. The exposure assessment component models temporal and spatial variability of air quality in the four study areas over the study duration using land-use regression modelling (LUR). Additionally, daily pollen levels (mould spores, tree, grass and weed pollen) in the study areas are recorded. In the panel study asthma symptoms and serial peak flow measurements is recorded three times daily to determine short-term serial airway changes in relation to varying ambient air quality and pollen over 10-days during winter and summer. The health outcome component of the cohort study include; the presence of asthma using a standardised ISAAC questionnaire, spirometry, fractional exhaled nitric-oxide (FeNO) and the presence of atopy (Phadiatop).

DISCUSSION

This research applies state of the art exposure assessment approaches to characterize the effects of ambient air pollutants on childhood respiratory health, with a specific focus on asthma and markers of airway inflammation (FeNO) in South African informal settlement areas by considering also pollen counts and meteorological factors. The study will generate crucial data on air pollution and asthma in low income settings in sub-Sahara Africa that is lacking in the international literature.

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.

Burden of asthma and chronic obstructive pulmonary disease and access to essential medicines in low-income and middle-income countries

Demographic and epidemiological transitions are changing the age structure of the population and the most common diseases. Non-communicable respiratory diseases are an increasing problem at both ends of the age range in low-income and middle-income countries. In children, who represent a large proportion of the total population, the increasing problem of asthma is a strain on health services. Improved survival of the older population is increasing the proportion of morbidity and mortality attributable to chronic lung diseases. Health services in low-resource countries are poorly adapted to treating chronic diseases. Designed to respond episodically to acute disease, almost all historical investment has focused on infectious diseases. Crucial to the successful management of chronic diseases is an infrastructure designed to support pro-active management, providing not only an accurate diagnosis, but also a secure supply of cost effective drugs at an affordable price. The absence of such an infrastructure in many countries and the market failure that makes drugs generally more expensive in low-resource regions means that many people with chronic non-communicable lung diseases are not given effective treatment. This has damaging economic consequences. The common causes of poor lung health in low-income countries are not the same as those in richer countries, and there is a need to study why they are so common and how best to manage them.

Meteorological conditions, climate change, new emerging factors, and asthma and related allergic disorders. A statement of the World Allergy Organization

The prevalence of allergic airway diseases such as asthma and rhinitis has increased dramatically to epidemic proportions worldwide. Besides air pollution from industry derived emissions and motor vehicles, the rising trend can only be explained by gross changes in the environments where we live. The world economy has been transformed over the last 25 years with developing countries being at the core of these changes. Around the planet, in both developed and developing countries, environments are undergoing profound changes. Many of these changes are considered to have negative effects on respiratory health and to enhance the frequency and severity of respiratory diseases such as asthma in the general population.

Increased concentrations of greenhouse gases, and especially carbon dioxide (CO₂), in the atmosphere have already warmed the planet substantially, causing more severe and prolonged heat waves, variability in temperature, increased air pollution, forest fires, droughts, and floods – all of which can put the respiratory health of the public at risk. These changes in climate and air quality have a measurable impact not only on the morbidity but also the mortality of patients with asthma and other respiratory diseases. The massive increase in emissions of air pollutants due to economic and industrial growth in the last century has made air quality an environmental problem of the first order in a large number of regions of the world. A body of evidence suggests that major changes to our world are occurring and involve the atmosphere and its associated climate. These changes, including global warming induced by human activity, have an impact on the biosphere, biodiversity, and the human environment. Mitigating this huge health impact and reversing the effects of these changes are major challenges.

This statement of the World Allergy Organization (WAO) raises the importance of this health hazard and highlights the facts on climate-related health impacts, including: deaths and acute morbidity due to heat waves and extreme meteorological events; increased frequency of acute cardio-respiratory events due to higher concentrations of ground level ozone; changes in the frequency of respiratory diseases due to trans-boundary particle pollution; altered spatial and temporal distribution of allergens (pollens, molds, and mites); and some infectious disease vectors. According to this report, these impacts will not only affect those with current asthma but also increase the incidence and prevalence of allergic respiratory conditions and of asthma. The effects of climate change on respiratory allergy are still not well defined, and more studies addressing this topic are needed. Global warming is expected to affect the start, duration, and intensity of the pollen season on the one hand, and the rate of asthma exacerbations due to air pollution, respiratory infections, and/or cold air inhalation, and other conditions on the other hand.

Effect of Submaximal Warm-up Exercise on Exercise-induced Asthma in African School Children

BACKGROUND

Regular physical activity has long been regarded as an important component of a healthy lifestyle. Exercise-induced asthma (EIA) is one of the major problems interfering with the performance of exercise. A warm-up exercise programme has been cited as a non-pharmacologic means of reducing EIA, but its effect has not been fully elucidated.

OBJECTIVE

The aims of this study were to determine the prevalence of unrecognized EIA in Pretoria primary school children, determine the effect of a warm-up exercise programme on EIA and to establish the relationship between history of allergy, family history of asthma and EIA.

METHODS

A random sample of 640 school children was selected. The study was divided into three phases. In phase one, a descriptive cross-sectional study was done using the standardized European Community Respiratory Health Survey (ECRHS) questionnaire. In phase two, non-asthmatic participants that returned a completed questionnaire were included in the field study. Pre-test and post-test experimental designs were used, where peak expiratory flow rate (PEFR) was measured at baseline and within ten minutes after exercise. A total of 340 subjects completed the Free Running Asthma Screening Test (FRAST); EIA was defined as a decrease in baseline PEFR ≥ 10% after exercise and 75 children (22%) had EIA. In phase three, 29 of the 75 subjects participated in the warm-up programme which was performed in the laboratory and subjects acted as their own controls. Predefined protocols for the study were followed.

RESULTS

Seventy-five (22%) of the 340 participants had EIA. The mean age, height and weight were 10.51 years, 139.26 cm and 33.45 kg, respectively. Exercise-induced asthma symptoms were cough (25%), chest pain (16%), wheeze (12%) and chest tightness (12%). The history of allergy was 75%, family history of allergy 40% and positive history of allergy when near animals, feathers or in dusty areas 38%. Wheezing during or after exercise, wheezing when near animals, feathers or in dusty areas and chest pain was significant (p < 0.05). The mean PEFR after exercise without warm-up was 4.43 L/min. The mean PEFR after exercise (warm-up) was 4.98. The mean percentage change in PEFR between exercise without warm-up and exercise with warm-up was 14.83%. The paired t-test showed a significant difference between PEFR with warm-up and PEFR without warm-up (p < 0.05).

CONCLUSION

There was a high prevalence of EIA among study participants. Exercise-induced asthma symptoms were significant for wheezing and chest pain. Exercise after warm-up was significant in reducing EIA. This study reports the effect of warm-up exercise on EIA and highlights the need to screen school children for EIA.

Pediatric asthma and ambient pollutant levels in industrializing nations

Asthma is one of the most common chronic diseases in childhood and its prevalence has been increasing within industrializing nations. The contribution of ambient pollutants to asthma symptomatology has been explored in some countries through epidemiological investigations, molecular analysis and monitoring functional outcomes. The health effects of rising environmental pollution have been of increasing concern in industrializing nations with rising urbanization patterns. This review article provides an overview of the link between pediatric asthma and exposure to rising sources of urban air pollution. It primarily focuses on the asthma-specific effects of sulfur dioxide, nitrogen dioxide, ozone and particulate matter. Worldwide trends of asthma prevalence are also provided which detail the prominent rise in asthma symptoms in many urban areas of Africa, Latin America and Asia. The molecular and functional correlation of ambient pollutants with asthma-specific airway inflammation in the pediatric population are also highlighted. The final aspect of the review considers the correlation of motor vehicle, industrial and cooking energy sources, ascribed as the major emitters among the pollutants in urban settings, with asthma epidemiology in children.

Asthma and the immune response to MMR vaccine viruses in Somali immigrant children: a cross-sectional retrospective cohort study

Background:

According to the ‘hygiene hypothesis’, an increase in microbial exposure in childhood leads to a T-helper cell 1 (Th1) predominant immune response and protection against asthma and atopic conditions.

Aims:

To assess the prevalence of asthma and other atopic conditions in Somali immigrants and to determine the humoral immune response to the measles, mumps, and rubella (MMR) vaccine viruses in Somali immigrants with asthma.

Methods:

A retrospective cohort study was conducted in Olmsted County, Minnesota. Study subjects were Somali immigrants who were born and lived in Africa during childhood and immigrated to the USA. The subjects had participated in a previous MMR vaccine study. Asthma was ascertained using predetermined asthma criteria after a thorough medical record review. An atopic condition was determined from physician-diagnosed ICD codes. Virus-specific IgG levels in response to the MMR vaccine viruses were determined using an enzyme immunoassay.

Results:

Of the 62 eligible subjects, 33 (53%) were female and 29 (47%) were male; 10 (16%) had asthma and 22 (35%) had other atopic conditions. There was no difference in the rubella (p=0.150) and measles (p=0.715) virus-specific IgG levels between the subjects with and without asthma. Mumps virus-specific IgG antibody levels were lower in those with asthma than in those without asthma (mean±SE 2.08±0.28 vs. 3.06±0.14, p=0.005).

Conclusions:

Our study results may not support the hygiene hypothesis. In addition, the previously reported abnormal T-cell development in Caucasian children with atopy can be considered even in Somali immigrants.

Socio-epidemiological Aspects of Respiratory Allergic Diseases in Southern Africa

The prevalence of respiratory allergic diseases has been increasing in Southern Africa both in urban and in rural environments. Various factors may contribute toward this situation, namely, exposure to aeroallergens, such as grass pollens and house dust mites. However, other irritant environmental triggers, such as exposure to tobacco smoke and certain indoor and outdoor fumes, may also play a relevant part. Furthermore, certain parasitic and mycobacterial infections may act as allergic disease risk modifiers, although such an influence should be confirmed. Finally, certain cultural and socioeconomic factors may also influence accessibility to healthcare and adherence to treatment of these diseases.

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 longitudinal study of allergy and intestinal helminth infections in semi urban and rural areas of Flores, Indonesia (ImmunoSPIN Study)

Background

The prevalence of asthma and atopic disease has been reported to be low in low income countries, however helminth infections are likely to be high among these communities. The question of whether helminth infections play a role in allergic diseases can best be addressed by intervention studies. None of the studies so far have been based on a large scale placebo-controlled trial.

Method/Design

This study was designed to assess how intestinal helminth infections can influence the immune response and atopic and allergic disorders in children in Indonesia. The relations between allergic outcomes and infection and lifestyle factors will be addressed. This study was set up among school-age children in semi urban and rural areas, located in Ende District of Flores Island, Indonesia. A randomized placebo-controlled anthelmintic treatment trial to elucidate the impact of helminth infections on the prevalence of skin prick test (SPT) reactivity and symptoms of allergic diseases will be performed. The children living in these semi-urban and rural areas will be assessed for SPT to allergens before and after 1 and 2 years of treatment as the primary outcome of the study; the secondary outcome is symptoms (asthma and atopic dermatitis); while the tertiary outcome is immune responses (both antibody levels to allergens and cellular immune responses).

Discussion

The study will provide information on the influence of helminth infections and anthelmintic treatment on immune response, atopy and allergic disorders.

Trial registration

Current Controlled Trials ISRCTN: ISRCTN83830814

GSTM1, GSTP1, and NQO1 polymorphisms and susceptibility to atopy and airway hyperresponsiveness among South African schoolchildren

Glutathione-S-transferases (GSTM1 and GSTP1) and nicotinamide quinone oxidoreductase (NQO1) genes play an important role in cellular protection against oxidative stress which has been linked to asthma pathogenesis. We investigated whether common, functional polymorphisms in GSTM1, GSTP1 and NQO1 influence airway hyperreactivity (AHR) and atopy among schoolchildren in South Africa. Genomic DNA was extracted from 317 primary schoolchildren, aged 9-11 years, from urban, low socioeconomic communities of Durban, South Africa. GSTM1 (null vs. present genotype), GSTP1 (Ile105Val; AA → AG + GG), and NQO1 (Pro/187Ser; CC → CT/TT) genotypes were determined using polymerase chain reaction (PCR) methods. Atopy was defined as a positive skin-prick test to any of several common allergens. Airway hyperreactivity (AHR) was evaluated by pulmonary function testing before and after methacholine challenge. Among the children, 30% were GSTM1 null, 65% carried the G allele for GSTP1, and 36% carried the C allele for NQO1. The frequency of GSTM1, GSTP1, and NQO1 variants among our South African sample was similar to frequencies found in similar ethnic groups worldwide. Marked airway reactivity (PC(20) ≤ 2 mg/ml) was found in 10.3% of children and approximately 40% of them were atopic. No significant associations for GSTM1 and NQO1 with either AHR or atopy were identified. A significant protective effect against atopy was found among children with one or two copies of the GSTP1 G allele.

Allergic disorders in Africa and africans: is it primarily a priority?

In Africa, the burden of some diseases has been a problem for centuries. The spectrum of African diseases includes allergies, infections, nutritional deficiencies, and natural disasters. Efforts made by scientists to search for possible means of disease control have been outstanding; however, in some infections, solutions are still out of reach. In disease control programs, it might be worthwhile to pay attention to the most striking diseases than merely follow a holistic approach. This short review tackles the problems of allergy and allergens in Africa as compared with other disease burdens that may suggest the need for a more balanced approach based on priority.

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.

Urban residence is associated with bronchial hyperresponsiveness in Italian general population samples

BACKGROUND

The role of different risk factors for bronchial hyperresponsiveness (BHR), such as gender, atopy, IgE, and environmental factors (smoking, occupational exposure, infections), has been described. Indoor and outdoor pollution play an important role too, but few studies have analyzed the association with BHR. The aim of this study was to assess the effect of urban residence on BHR.

METHODS

We studied two general population samples enrolled in two cross-sectional epidemiological studies performed in Northern Italy (Po Delta, rural area) and Central Italy (Pisa, urban area). We analyzed 2,760 subjects (age range, 8 to 74 years). We performed analysis of variance and logistic regression analysis using ln slope of the dose-response curve of the methacholine challenge test as dependent variable, and sex, age, smoking habits, respiratory symptoms, skin-prick test results, IgE value, residence, and airway caliber as independent variables.

RESULTS

The mean value of ln slope of the dose-response curve adjusted for initial airways caliber (by baseline FEV(1) percentage of predicted value) was significantly higher in female subjects, in smokers, in subjects with respiratory symptoms, in younger and older ages, in subjects with high values of IgE, and in subjects with positive skin-prick test results. After controlling for the independent effects of all these variables, living in urban area was an independent risk factor for having BHR (odds ratio, 1.41; 95% confidence interval, 1.13 to 1.76).

CONCLUSION

Living in urban area is a risk factor for increased bronchial responsiveness.

Household conditions, eczema symptoms and rhinitis symptoms: relationship with wheeze and severe wheeze in children living in the Polokwane area, South Africa

BACKGROUND

This is the fifth study that applied the International Study of Asthma and Allergies in Childhood (ISAAC) methodology in the Southern African Development Community (SADC region). However, it is the first ISAAC study that focused on 6- to 7-year-old children living in South Africa and that also investigated the association between potential risk factors and asthma symptoms. Objective To assess the 12-month prevalence of wheeze and severe wheeze along with their potential risk factors. Setting Within a 60-km radius from the Polokwane city centre, Limpopo Province.

METHODS

The survey was conducted during August 2004 and February 2005. Parents/guardians of 6- to 7-year-old children completed the questionnaires in English, Afrikaans or North-Sotho. However, the statistical analyses were restricted to the North-Sotho group (n = 2,437).

RESULTS

The 12-month prevalence rates of wheeze and severe wheeze were 11.2% and 5.7%, respectively. The 12-month prevalence rates of eczema symptoms and rhinoconjunctivitis symptoms were 8.0% and 7.3%, respectively. Living in a rural area significantly decreased the likelihood of wheeze by 31%. Exposure to environmental tobacco smoke at home and the presence of eczema symptoms and rhinoconjunctivitis symptoms increased the likelihood of wheeze by 77%, 104% and 226%, respectively. Only the presence of rhinoconjunctivitis symptoms increased the likelihood of severe wheeze by 107%.

CONCLUSION

Wheeze appears to be an emerging public health problem in the Polokwane area. Hopefully, detailed analytical intervention studies will further explicate these results in the near future.

Household conditions, eczema symptoms and rhinitis symptoms: relationship with wheeze and severe wheeze in adolescents living in the Polokwane area, South Africa

OBJECTIVE

Determine the prevalence and risk factors of wheeze and severe wheeze in 13-to 14-year-old children.

METHODS

The study was conducted August 2004 to February 2005 in the Polokwane area, South Africa.

RESULTS

The 12-month prevalence rate was 18.9% for wheeze and 9.2% for severe wheeze (n = 3,926). The presence of other allergic symptoms and industrial activities appear to increase the likelihood of wheeze, even more so for severe wheeze. Socioeconomic-related factors appear to have a protective effect on wheeze.

CONCLUSIONS

Wheeze appears to be a substantial public health problem in the Polokwane area.

The changing prevalence of asthma, allergic rhinitis and atopic eczema in African adolescents from 1995 to 2002

The prevalence of asthma and allergic disease in children has been increasing in developed countries, but there is little information on these trends in Africa. The aim of this study was to assess time trends in the symptoms of asthma, allergic rhinitis, and atopic eczema among South African adolescents. The study was carried out by comparing cross-sectional data from two International Study of Asthma and Allergies in Childhood (ISAAC phase I and phase III) questionnaire based surveys conducted 7 yr apart of self-reported symptoms in 13- to 14-yr-old adolescents. In both surveys, schools in the same geographical area in Cape Town, South Africa, were randomly selected. A school-based sample of 5178 (in 1995) and 5037 (in 2002) pupils participated. The 12-month prevalence of wheezing (16% vs. 20.3%), exercise-induced wheeze (21.5% vs. 32.5%), nocturnal cough (23.6% vs. 36.6%), sleep disturbance due to wheeze (9.6% vs. 16%), or severe wheeze (5.1% vs. 7.8%) increased significantly, as measured by the written questionnaire. A rise in asthma symptoms was confirmed by the video questionnaire responses, in which the 12-month prevalence of wheezing (6.5% vs.11.2%), exercise-induced wheeze (11.5% vs. 13.9%), nocturnal wheeze (3.9% vs. 5.3%), nocturnal cough (11.6% vs. 19.2%), or severe wheeze (5% vs. 7%) also increased significantly. There was a small increase in the percentage of children diagnosed with asthma from 1995 to 2002 (13.1% vs. 14.4%), this was not significant. The 12-month prevalence of symptoms of allergic rhinitis (30.4% vs. 38.5%), rhinoconjunctivitis (17.6% vs. 24.3%) and eczema (11.8% vs. 19.4%) also increased significantly. An increase in the prevalence of allergic symptoms occurred in girls and boys. Limitation of daily activity from nasal symptoms (22.3% vs. 37.8%) and sleep disturbance because of eczema (8.4% vs. 15.7%) increasingly affected quality of life on the quality of life. Symptoms of asthma, allergic rhinitis and atopic eczema in adolescents have increased over the past 7 yr in this geographical area. Allergic diseases are common in this group of adolescents and increasingly impair their quality of life.

Distinctive immunoglobulin E anti-house dust allergen-binding specificities in a tropical Australian Aboriginal community

BACKGROUND

There is evidence that the specificity of the IgE binding in allergy tests can vary for different populations.

OBJECTIVE

We aimed to examine the allergenic specificity of IgE binding in sera from house dust mite (HDM)-atopic subjects in a tropical Australian Aboriginal community.

METHODS

Sera shown to contain IgE antibodies to an HDM extract of Dermatophagoides pteronyssinus were examined for IgE binding to a panel of nine purified HDM allergens from this mite species by quantitative microtitre assays. IgG antibody binding (IgG1 and IgG4) was also measured.

RESULTS

The IgE-binding activity in the sera from the Aboriginal community was not directed to the expected major groups 1 and 2 HDM allergens but instead to the group 4 amylase allergen. There was also little IgE binding to the potentially cross-reactive tropomyosin (Der p 10) or arginine kinase (Der p 20) allergens. The IgG4 antibody was rarely detected and limited to the Der p 4 allergen. IgG1 antibody binding was frequently measured to all the allergens regardless of an individual's atopic status, whereas in urban communities it is restricted to the major allergens and to atopic subjects.

CONCLUSION

The high IgE anti-HDM response of Australian Aboriginals predominantly bound Der p 4 and not the Der p 1 and 2 allergens, showing a distinctive allergy that could affect the disease outcome and diagnosis.

Aeroallergen sensitization in healthy children: racial and socioeconomic correlates

OBJECTIVE

Allergic sensitization is very prevalent and often precedes the development of allergic disease. This study examined the association of race with allergic sensitization among healthy children with no family history of atopy.

STUDY DESIGN

Two hundred seventy-five children, predominantly from lower socioeconomic strata, from Cincinnati, Ohio, ages 2 to 18 years without a family or personal history of allergic diseases, underwent skin prick testing to 11 allergen panels. The Pediatric Allergic Disease Quality of Life Questionnaire (PADQLQ) was used to examine the impact of sensitization on quality of life.

RESULTS

Thirty-nine percent of healthy children were sensitized to 1 or more allergen panels. Multivariate logistic regression showed increased risk among African-American children for any sensitization (OR, 2.17; [95% CI: 1.23, 3.84]) and sensitization to any outdoor allergen (OR, 2.96 [95% CI: 1.52, 5.74]). Eighty-six percent of children had PADQLQ scores of 1 or less (0 to 6 scale).

CONCLUSIONS

Allergic sensitization is prevalent even among children who do not have a personal or family history of asthma, allergic rhinitis, or atopic dermatitis and who have no evidence of current, even subtle effects from this sensitization on allergic disease-related quality of life. African-American children are at greater risk for presence of sensitization, especially to outdoor allergens.

Increased sensitization in urban vs. rural environment--rural protection or an urban living effect?

In a population-based longitudinal cohort study, we tested the hypothesis that children growing up in a high-traffic polluted urban area (UA) in the Athens' basin have higher prevalence of allergies and sensitization when compared with those growing up in a Greek provincial rural area (RA). We recruited 478 and 342 children aged 8-10 living in the UA and the RA, respectively. Respiratory health was assessed by a parent-completed questionnaire in three phases: 1995-96 (phase 1), 1999-2000 (phase 2), 2003-04 (phase 3) and skin-prick testing to common indoor and outdoor aeroallergens was performed at phases 1 and 2. Reported asthma and eczema did not differ between the two areas, whereas reported hay fever was persistently more prevalent in the UA than in the RA (16.5%, 17.0%, 18.2% vs. 7.0%, 8.3%, 9.6%, respectively). Sensitization was more prevalent in the UA at both phases (19.0% vs. 12.1% in phase 1, 20.0% vs. 14.1% in phase 2). Residential area contributed independently to sensitization to >or=1 aeroallergens (OR: 0.29; 95% CI: 0.13-0.66; p = 0.003) and to polysensitization (OR: 0.28; 95% CI: 0.10-0.82; p = 0.020) in phase 1. These associations were independent of farming practices. No significant contributions were found in phase 2. Our results suggest that long-term exposure to urban environment is associated with a higher prevalence of hay fever but not of asthma or eczema. The negative association between rural living and the risk of atopy during childhood, which is independent of farming practices, implies that it is mainly driven by an urban living effect.

Atopy and asthma in rural Poland: a paradigm for the emergence of childhood respiratory allergies in Europe

BACKGROUND

We hypothesized that, in south-west Poland, a 'rural' protective effect on atopy and respiratory allergies would be most pronounced among children but that at all ages would be stronger among those with a rural background.

METHODS

A cross-sectional survey of the inhabitants (age >5 years, n = 1657) of Sobotka, a town of 4000 people in south-west Poland: and seven neighbouring villages. We measured and analysed responses to skin prick tests (atopy) and to a standard questionnaire (asthma and hayfever).

RESULTS

Atopy was very uncommon (7%) among villagers at all ages but not among townspeople (20%, P < 0.001); the differences were most marked among those aged under 40 years. Asthma and hayfever were similarly distributed, both being very rare among villagers. The differences appear to be explained by the cohort effect of a communal move away from rural life. This interpretation is supported by an ecological correlation (rho = -0.59) between rural populations and childhood wheeze in 22 European countries.

CONCLUSION

The very striking differences in the prevalence of allergy between these two neighbouring communities of central Europe reflect the pan-continental population movements that may have been responsible for the emergence of childhood allergies in Europe.

Allergic disorders in African countries: linking immunology to accurate phenotype

Identification and characterization of risk and protective factors for allergy is important for developing strategies for prevention or treatment. The prevalence of allergy is clearly higher in affluent countries than in developing countries like, e.g. Africa. Especially in urban areas of developing countries, allergy is however on the increase. In Africa, we have the unique opportunity to investigate risk and protective factors and the influence of urbanization and westernization, i.e. almost to take a look at Europe, Australia or the USA as they were before their allergy epidemics. Moreover, migrants from developing to affluent countries experiencing an increased burden of allergy provide new insights into risk and protective factors. Allergen exposure, diet and infections are the major exogenous influences playing a role as risk and protective factors. Depending on the nature, timing, chronicity and level of exposure, each of them can promote or inhibit allergy. Perhaps with the exception of infections, availability of data from Africa on their role in the development of allergy is limited. Detailed epidemiological studies in rural and urban Africa combined with basic immunological research are needed to unravel mechanisms of increase in allergy and of protection. The maturation of the immune system at young age under influence of exogenous factors results in differences in T-cell-skewing (Th1/Th2/Treg) and humoral responses. It is essential to perform studies from a 'non-Eurocentric' angle (e.g. local allergens, locally validated questionnaires and diagnostic procedures). Such studies will provide the affluent countries with new leads to combat the allergy epidemic and more importantly help prevent it in Africa.

The role of helminth infections in protection from atopic disorders

PURPOSE OF REVIEW

The observation that allergies are less prevalent in developing countries, especially in rural areas, has stimulated considerable research to identify environmental factors associated with protection against allergic disorders. Here, we review recent studies conducted in developing countries.

RECENT FINDINGS

Epidemiological studies conducted in South America, Asia and Africa have attempted to identify factors associated with differences in prevalence of atopy, asthma and atopic dermatitis. Particular attention is given to the complex relationship between helminth infections and allergies. In answer to the question of whether helminth infections are associated with protection against allergic disorders, conflicting data have been generated. In addition to epidemiological studies, animal models have been utilized to gain insight into the immunological mechanisms involved in the interaction between helminth infections and allergies. These animal studies are discussed. The possible explanations for discrepancies found within both human and murine studies have been considered, highlighting the need for further research.

SUMMARY

An in-depth understanding of the relevant protective mechanisms against allergic disorders will open the possibility of developing novel therapeutics to prevent the allergic march worldwide.

Allergy practice worldwide: a report by the World Allergy Organization Specialty and Training Council

In 2004 the World Allergy Organization's Specialty and Training Council conducted a survey of World Allergy Organization (WAO) member societies to obtain information about the status of the specialty of allergy worldwide. Responses were received from 33 countries, representing a population of 1.39 billion people, of whom it was estimated that 22% may suffer from some form of allergic disease. Allergy was reported by 23 respondents to be a certified or accredited specialty in their country, and the number of certified allergists per head of population ranged from 1:25 million to 1:16,000. Allergists were ranked as the fifth most likely clinicians to see cases of allergic asthma, third most likely to see allergic rhinitis, and fourth most likely to see eczema or sinusitis. Nine countries only reported that children with allergic diseases would be seen by a pediatrician with appropriate training. The survey results highlight a pressing need for the development of allergy services worldwide.

Low prevalence of latex sensitivity in South African spina bifida children in Cape Town

Spina bifida children have a high prevalence of latex allergy in studies reported from Europe and the USA. This study investigated the prevalence of latex allergy in a cohort of 24 spina bifida children at the Red Cross Children's Hospital from Cape Town, South Africa. The children were investigated using a detailed questionnaire, skin prick tests (ALK-Abello), ImmunoCap RASTs, Western blotting and ELISA, using the purified latex proteins Hev b1 and Hev b3 and whole latex preparation. A low overall prevalence of latex sensitization of 16.7% was found in the children. Children who were sensitive reacted to water insoluble to Hev b1 and Hev b3 proteins. The low prevalence of latex sensitization in the South African children may not be entirely explained by stringent latex avoidance. The children were from a low socioeconomic social status and 'hygiene' and other factors should be considered.