Andrea Venn

Independent effects of intestinal parasite infection and domestic allergen exposure on risk of wheeze in Ethiopia: a nested case-control study

BACKGROUND Why asthma is rare in rural subsistence societies is not clear. We tested the hypotheses that the risk of asthma is reduced by intestinal parasites or hepatitis A infection, and increased by exposure to dust-mite allergen or organophosphorus insecticides in urban and rural areas of Jimma, Ethiopia. METHODS From 12876 individuals who took part in a study of asthma and atopy in urban and rural Jimma in 1996, we identified all who reported wheeze in the previous 12 months, and a random subsample of controls. In 1999, we assessed parasites in faecal samples, Der p 1 levels in bedding, hepatitis A antibodies, serum cholinesterase (a marker of organophosphorus exposure), total and specific serum IgE, and skin sensitisation to Dermatophagoides pteronyssinus in 205 cases and 399 controls aged over 16 years. The effects of parasitosis, Der p 1 level, hepatitis A seropositivity, and cholinesterase concentration on risk of wheeze, and the role of IgE and skin sensitisation in these associations, were analysed by multiple logistic regression. FINDINGS The risk of wheeze was independently reduced by hookworm infection by an odds ratio of 0.48 (95% CI 0.24-0.93, p=0.03), increased in relation to Der p 1 level (odds ratio per quartile 1.26 [1.00-1.59], p=0.05), and was unrelated to hepatitis A seropositivity or cholinesterase concentration. In the urban population, D pteronyssinus skin sensitisation was more strongly related to wheeze (9.45 [5.03-17.75]) than in the rural areas (1.95 [0.58-6.61], p for interaction=0.017), where D pteronyssinus sensitisation was common, but unrelated to wheeze in the presence of high-intensity parasite infection. INTERPRETATION High degrees of parasite infection might prevent asthma symptoms in atopic individuals.

Atopic eczema and domestic water hardness

BACKGROUND The environment plays an important part in the aetiology of atopic eczema, but specific causes are unknown. Exposure to hard water is thought to be a risk factor for eczema. We undertook an ecological study of the relation between domestic water hardness and the prevalence of eczema among Nottinghamshire schoolchildren. METHODS Questionnaire details of 1-year period and lifetime prevalence of eczema were obtained from parents of 4141 randomly selected primary-school children and 3499 secondary-school children in southern Nottinghamshire. Geographical information systems (GIS) were used to link the geographical distribution of eczema prevalence with domestic water-hardness data (four categories). Adjustment was made for potential confounding by sex, age, socioeconomic status, and access to health care. FINDINGS Among the primary-school children there was a significant direct relation between both 1-year period and lifetime prevalence of eczema and water hardness, both before and after adjustment for confounders. The 1-year period prevalence was 17.3% (261/1509) in the highest water-hardness category and 12.0% (94/786) in the lowest (adjusted odds ratio 1.54 [95% CI 1.19-1.99] p for trend <0.001). The corresponding values for lifetime prevalence were 25.4% (384/1509) and 21.2% (167/786; adjusted odds ratio 1.28 [1.04-1.58], p for trend=0.02). Eczema prevalence trends in the secondary-school population were not significant (adjusted odds ratio for highest compared with lowest hardness category for 1-year prevalence 1.03 [0.79-1.33], p for trend=0.46; for lifetime prevalence 0.99 [0.83-1.23], p for trend=0.93). Eczema prevalence in primary-school children increased in relation to chlorine content of water, but the trend across four chlorine-content categories was not independently significant after adjustment for confounders. INTERPRETATION Exposure to hard water in the home may increase the risk of eczema in children of primary-school age.

Experimental hookworm infection: a randomized placebo-controlled trial in asthma

Background Epidemiological studies suggest that hookworm infection protects against asthma, and therefore that hookworm infection may have a direct or an indirect therapeutic potential in this disease. We now report the first clinical trial of experimental hookworm infection in people with allergic asthma.

Questionnaire study of effect of sex and age on the prevalence of wheeze and asthma in adolescence

In early childhood wheezing and asthma are more common in boys than girls.1 This difference has either disappeared or reversed by early adulthood,2 although the age at which the change occurs is unclear. We therefore measured the age and sex specific prevalence of self reported wheeze and diagnosed asthma in 11-16 year old children attending secondary schools in the Nottingham area. In 1996 we completed a prevalence survey of all pupils attending 44 secondary schools in a defined postcode area in and around Nottingham. Questionnaires about lifetime and current wheeze and asthma diagnosed by a doctor (Appendix) were distributed to pupils for self completion during school time. Data were collected on 27 826 pupils (over 80% of registered pupils) aged 11-16 years, 51% of whom were boys. Parental responses to the same questions were obtained for a 1 in 4 random subsample of 3894 pupils (59% response). The self reported lifetime prevalence of wheeze was 30.1% (8317/27 632), with 19.0% …

Secondhand Smoke and Adverse Fetal Outcomes in Nonsmoking Pregnant Women: A Meta-analysis

OBJECTIVE: To determine the risk of adverse fetal outcomes of secondhand smoke exposure in nonsmoking pregnant women. METHODS: This was a systematic review and meta-analysis in accordance with Meta-analysis of Observational Studies in Epidemiology (MOOSE) guidelines. We searched Medline and Embase (to March 2009) and reference lists for eligible studies; no language restrictions were imposed. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were estimated by using random-effect models. Our search was for epidemiologic studies of maternal exposure to secondhand smoke during pregnancy in nonsmoking pregnant women. The main outcome measures were spontaneous abortion, perinatal and neonatal death, stillbirth, and congenital malformations. RESULTS: We identified 19 studies that assessed the effects of secondhand smoke exposure in nonsmoking pregnant women. We found no evidence of a statistically significant effect of secondhand smoke exposure on the risk of spontaneous abortion (OR: 1.17 [95% CI: 0.88–1.54]; 6 studies). However, secondhand smoke exposure significantly increased the risk of stillbirth (OR: 1.23 [95% CI: 1.09–1.38]; 4 studies) and congenital malformation (OR: 1.13 [95% CI: 1.01–1.26]; 7 studies), although none of the associations with specific congenital abnormalities were individually significant. Secondhand smoke exposure had no significant effect on perinatal or neonatal death. CONCLUSIONS: Pregnant women who are exposed to secondhand smoke are estimated to be 23% more likely to experience stillbirth and 13% more likely give birth to a child with a congenital malformation. Because the timing and mechanism of this effect is not clear, it is important to prevent secondhand smoke exposure in women before and during pregnancy.

Exposure to Secondhand Smoke and Biomarkers of Cardiovascular Disease Risk in Never-Smoking Adults

Background— Exposure to secondhand smoke has been associated with a disproportionately high risk of coronary heart disease, thought to be mediated through inflammation, platelet aggregation, and/or endothelial dysfunction. The epidemiological association between objectively measured exposure to secondhand smoke and biomarkers of heart disease risk has not been investigated, however. Methods and Results— We have investigated the cross-sectional relation between secondhand smoke exposure, measured objectively as cotinine, and recognized biomarkers of heart disease risk, namely C-reactive protein, homocysteine, fibrinogen, and white blood cell count, in 7599 never-smoking adults from the Third National Health and Nutrition Examination Survey. Compared with subjects with no detectable cotinine, those with detectable but low-level cotinine (range, 0.05 to 0.215 ng/mL) had significantly higher levels of both fibrinogen (adjusted mean difference, 8.9 mg/dL; 95% CI, 0.9 to 17.0; P=0.03) and homocysteine (0.8 &mgr;mol/L; 95% CI, 0.4 to 1.1; P<0.001) but not C-reactive protein or white blood cell count. Effect estimates of similar magnitude and significance were seen in subjects in the high category of cotinine exposure (>0.215 ng/mL). The increased levels of fibrinogen and homocysteine seen in relation to secondhand smoke exposure were equivalent to ≈30% to 45% of those seen for active smoking. Conclusions— Passive smokers appear to have disproportionately increased levels of 2 biomarkers of cardiovascular disease risk, fibrinogen and homocysteine. This finding provides further evidence to suggest that low-level exposure to secondhand smoke has a clinically important effect on susceptibility to cardiovascular disease.

Local road traffic activity and the prevalence, severity, and persistence of wheeze in school children: combined cross sectional and longitudinal study

OBJECTIVES To investigate the relation between local road traffic activity and the occurrence, severity, and persistence of wheeze in children. METHODS Data on wheeze and asthma were collected in a cross sectional questionnaire survey of 22 968 primary school children (age 4–11) and 27 826 secondary school children (age 11–16) in the Nottingham area. Direct measures of road traffic flow were made in the locality of each school and combined with Local Authority traffic data for major roads to estimate local traffic activity in vehicle metres/day/km2. Assessment of the effects of potential confounders was performed in nested case-control groups of 6576 primary and 5936 secondary children. Data on frequency of wheeze were collected for the cases to study disease severity. Longitudinal data on a historical cohort of 883 children who reported wheeze when aged 4–11 in 1988 were used to study the persistence of wheeze into adolescence. RESULTS Unadjusted prevalence of wheeze in the past year within schools varied widely but was not associated with traffic activity in the school locality (weighted regression coefficient β=−0.01, p=0.93 for primary schools, β=−0.18, p=0.26 for secondary schools). The risk of wheeze in individual primary school children was not associated with traffic activity analysed as a continuous variable, although there was some suggestion of a weak, non-linear plateau effect. Similar effects were found for diagnosed asthma and recent cough. There was no evidence of any relation between traffic activity and risk of wheeze in secondary school children. There were positive but non-significant dose related effects of traffic activity on wheeze severity in primary and secondary children and on persistence of wheeze in the longitudinal cohort. CONCLUSIONS Traffic activity in the school locality is not a major determinant of wheeze in children.

Effects of volatile organic compounds, damp, and other environmental exposures in the home on wheezing illness in children

Background: The effects of indoor exposure to volatile organic compounds (VOCs), including formaldehyde, on respiratory health are not clearly understood. The aim of this study was to determine the independent effects of VOCs and other common environmental exposures in the home on the risk and severity of persistent wheezing illness in children. Methods: Total volatile organic compounds, formaldehyde, nitrogen dioxide, damp (on a four category scale of % wood moisture equivalent), and environmental tobacco smoke (from salivary cotinine) were measured objectively in the homes of 193 children with persistent wheezing illness and 223 controls aged 9–11 years in Nottingham, UK. Results: The risk of wheezing illness was significantly increased only in relation to damp (odds ratio (OR) per increasing category=1.32 (95% confidence interval (CI), 1.00 to 1.75)), and was unrelated to the other exposures measured. Among cases, formaldehyde and damp were associated with more frequent nocturnal symptoms (OR per increasing quartile and category, respectively, 1.45 (1.06 to 1.98) and 1.97 (1.10 to 3.53)), significantly more so in atopic cases, but there was no effect of total volatile organic compounds, nitrogen dioxide, or cotinine. Conclusions: Domestic volatile organic compounds are not a major determinant of risk or severity of childhood wheezing illness, though formaldehyde may increase symptom severity. Indoor damp increases both the risk and severity of childhood wheezing illness.

Effects of Helicobacter pylori, geohelminth infection and selected commensal bacteria on the risk of allergic disease and sensitization in 3-year-old Ethiopian children

Background Epidemiological studies have suggested that gastro‐intestinal infections including Helicobacter pylori, intestinal microflora (commensal bacteria) and geohelminths may influence the risk of asthma and allergy but data from early life are lacking.

Prevalence and associated factors of atopic dermatitis symptoms in rural and urban Ethiopia

Background Allergic diseases, including atopic dermatitis (AD), are increasingly becoming a clinical problem in developing countries.