Infectious burden as a determinant of atopy-- a comparison between adults in Finnish and Russian Karelia

BACKGROUND: Evidence of the influence of pathogen exposure on the development of atopy and atopic disease is not unequivocal. We investigated the association between markers of infections and occurrence of atopy among adults in eastern Finland and western Russia, two adjacent areas with profound differences in living conditions and lifestyles. METHODS: Randomly selected adults aged 25-54 years from Finland (n = 790) and from Russia (n = 387) participated in the study. Skin prick tests were performed to 11 common airborne allergens, and at least one positive prick reaction was considered to indicate atopy. Antibodies to different pathogens including hepatitis A virus (HAV), Helicobacter pylori, Toxoplasma gondii, herpes simplex virus (HSV), Chlamydia pneumoniae and the periodontal pathogens Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans were measured. RESULTS: In Finland 34.3% and in Russia 23.3% of the study population was atopic (p < 0.001). Seroprevalences to all these pathogens were significantly higher among the Russians. In multivariate logistic regression analysis, only H. pylori was inversely associated with atopy in Russia. A further stepwise analysis revealed that H. pylori alone can explain 32% of the difference in atopy between the countries, and T. gondii, A. actinomycetemcomitans, HSV and C. pneumoniae had a slightly additive effect, whereas, unexpectedly, seropositivity to HAV and, to a lesser extent, P. gingivalis had an opposite effect. The net result of the stepwise analysis showed that 44% of the difference in atopy between the countries could be explained by seropositivity to these seven pathogens. CONCLUSIONS: Seropositivity to select pathogens, particularly to H. pylori, could explain a substantial part of the difference in atopy prevalence between Finland and Russia. Exposure to HAV was not associated with protection against atopy in this adult population.     

IgG antibodies against microorganisms and atopic disease in Danish adults: the Copenhagen Allergy Study

BACKGROUND: Seropositivity to food-borne and orofecal microorganisms (hepatitis A virus, Helicobacter pylori, and Toxoplasma gondii ), which are considered to be markers of poor hygiene, has been reported to be associated with a lower prevalence of atopy. In contrast, colonization of the gut with Clostridium difficile, a potential intestinal bacterial pathogen, in early childhood may be associated with a higher prevalence of atopy. OBJECTIVE: The objective of this study was to investigate the association between atopy and exposure to 2 groups of food-borne and orofecal microorganisms: (1) markers of a poor hygiene and (2) intestinal bacterial pathogens. METHODS: A cross-sectional population-based study of 15- to 69-year-olds living in Copenhagen, Denmark, was carried out in 1990 to 1991. Atopy was defined as a positive test result for specific IgE to at least 1 of 6 inhalant allergens. Exposure to microorganisms was assessed as IgG seropositivity to microorganisms. RESULTS: Seropositivity to 2 or 3 markers of poor hygiene (hepatitis A virus, H pylori, and T gondii ) was associated with a lower prevalence of atopy (adjusted odds ratio, 0.5; 95% CI, 0.3 to 0.8). In contrast, seropositivity to 2 or 3 intestinal bacterial pathogens (C difficile, Campylobacter jejuni, and Yersinia enterocolitica ) was associated with a higher prevalence of atopy (adjusted odds ratio, 1.7; 95% CI, 1.2 to 2.6). CONCLUSION: Exposure to markers of poor hygiene was associated with a lower prevalence of atopy, whereas exposure to intestinal bacterial pathogens was associated with a higher prevalence of atopy. These findings raise the hypothesis that different groups of food-borne and orofecal microorganisms may have different effects on the risk of atopy.     

Crete: does farming explain urban and rural differences in atopy?

BACKGROUND: Urban-rural differences in the prevalence of atopy and associated allergic diseases have been reported in several non-European countries. Within Europe, where such variations are less striking, a farm childhood has been postulated to be protective. OBJECTIVE: We aimed to compare the prevalence of atopy in urban and rural children living in Crete and to examine the role of early exposure to a farming environment in explaining any measured differences. METHODS: A cross-sectional survey of children attending secondary schools in Iraklion, the capital city, and five villages 100 km to the south. Atopy was determined by the responses to skin prick tests with seven common aeroallergens. RESULTS: Nine-hundred and ninety-seven children participated in the survey. 19.6% of those living in Iraklion, but only 9.6% of those from the villages, had a positive response to one or more skin prick tests. Among urban children there were significant gradients in the prevalence of atopy across several categories of animal contact and consumption of farm (unpasteurized) milk products--before the age of 5 years. These differences, however, were not apparent among the rural children.     

A seroepidemiologic study of Helicobacter pylori and hepatitis A virus infection in primary school students in Taipei.

Helicobacter pylori and hepatitis A virus (HAV) share a common fecal-oral transmission route. The aim of this study was to investigate the prevalence of and risk factors for H. pylori and HAV infection in primary school students in Taiwan. We studied 289 Grade 1 to 6 students from a single primary school in Taipei County in 2003. The students volunteered for blood tests for H. pylori immunoglobulin G (IgG) antibody and anti-hepatitis A antibody after consent from their parents. Questionnaires were administered to the parents to investigate possible risk factors. The seroprevalence rates of H. pylori IgG antibody and anti-hepatitis A antibody were 21.5% (62/289) and 1.4% (4/289), respectively. No statistically significant relationship was found between seropositivity for H. pylori and for HAV. If parents had knowledge of H. pylori and HAV, their children were significantly more likely to be seronegative for H. pylori (p=0.020, odds ratio [OR] 2.1, 95% confidence interval [CI] 1.2-3.7) and HAV (p=0.012, OR 11.2, 95% CI 1.5-83.4). Students whose family members had no history of HAV infection were significantly less likely to be seropositive for HAV (p=0.001, OR 0.04, 95% CI 0.004-0.5). No other factors were found to be significantly associated with seropositivity, including blood type; age; gender; family members' history of H. pylori infection; travel to China; parents' educational level; sources of water supply; family members' use of tobacco, alcohol, or betel nut; family members' history of peptic ulcer or gastritis; and students' history of recurrent abdominal pain. Lack of public health knowledge appears to be related to seroprevalence of H. pylori in primary school students. The low seroprevalence of anti-HAV antibodies demonstrates the lack of protection against this infection in school-age children in Taiwan and suggests that universal administration of HAV vaccine would be wise.     

Helicobacter pylori genotypes, host factors, and gastric mucosal histopathology in peptic ulcer disease

From 183 patients undergoing upper gastrointestinal endoscopy, we used antral and corpus gastric biopsies for bacterial culture and histopathologic examination, blood samples to detect immunoglobulin G antibodies against Helicobacter pylori, and H pylori genomic DNA to analyze cytotoxin-associated gene A (cagA) and vacuolating cytotoxin (vacA) genotypes. As expected, among H pylori biopsy-positive patients, those with duodenal ulcer (DU) (n = 34) had significantly more severe chronic and acute inflammation (P <.001) and epithelial degeneration (P =.004) in the gastric antrum than in the gastric corpus. Each of those 3 parameters and H pylori density were significantly higher in the antrum of patients with DU than in patients with gastric ulcer (GU) or no ulcer. Colonization with vacA s1/cagA-positive strains of H pylori was associated with inflammation and epithelial degeneration in gastric mucosa and increased risk for peptic ulcer disease (PUD), whereas colonization with vacA s2m2/cagA-negative strains was associated with mild gastric histopathology and was not associated with any significant risk for PUD. The predominant H pylori strains in African Americans were vacA s1bm1/cagA-positive, whereas all genotypes were well represented in non-Hispanic-Caucasians. By multivariate analysis, H pylori colonization was significantly associated with DU (Adjusted odds ratio [AdjOR] = 3.2 [1.4-7.2]) and nonsteroidal anti-inflammatory drugs (NSAID) use was inversely associated (AdjOR = 0.3 [0.2-0.7]). NSAID use (AdjOR = 4.3 [1.02-18.5]) and African-American ethnicity (AdjOR = 10.9 [2.6-50]) were significantly associated with GU. Smoking and age were not significantly associated with either DU or GU. These data indicate that DU is associated with an antral-dominant gastritis, and H pylori genotype and NSAID use independently contribute to the pathogenesis of PUD. HUM PATHOL 32:264-273. This is a US Government work. There are no restrictions on its use.     

Association between farm exposure and atopy, according to the CD14 C-159T polymorphism

BACKGROUND: A higher exposure to bacterial compounds is purported to explain the lower prevalence of allergy in farm children, but responsiveness to bacterial compounds is modulated by genetic factors. OBJECTIVE: To assess whether the protective effect of farm exposure on atopy is influenced by a CD14 promoter functional polymorphism. METHODS: We administered a detailed questionnaire on farm exposure in childhood and genotyped the CD14 C-159T polymorphism in 2 French centers participating in the European Community Respiratory Health Survey (ECRHS)-II. RESULTS: Six hundred randomly selected young adults provided blood samples for IgE measurements and had CD14 C-159T genotyped. Exposure to a farming environment in early life was associated with a reduced risk of nasal allergies (odds ratio [OR], 0.54; 95% CI, 0.29-1.00) and atopic sensitization (OR, 0.47; 95% CI, 0.24-0.93) in adulthood. A lower risk of allergic rhinitis and atopy was also observed in carriers of the CD14-159TT genotype compared with -159CC subjects (OR, 0.52; 95% CI, 0.30-0.88; and OR, 0.54; 95% CI, 0.31-0.92, respectively). When farm exposure and CD14 C-159T were considered together, the risk of nasal allergies and atopy was the most reduced in the subjects who combined both an early-life exposure to a farming environment and the -159TT genotype (OR, 0.26; 95% CI, 0.07-0.94; and OR, 0.21; 95% CI, 0.05-0.93, respectively, vs nonexposed -159CC+CT subjects). The results were consistent in the 2 centers, supporting the validity of the results. CONCLUSION: A gene-by-environment interaction between CD14 C-159T and environmental exposure in childhood may modify the development of atopy. CLINICAL IMPLICATIONS: This polymorphism should be considered in interventions studies that use microbial stimuli to reduce sensitization.     

Seropositivity to Helicobacter pylori: lack of association with length of hospitalization.

To examine the possibility of nosocomial spread of Helicobacter pylori, a serosurvey (n = 238) was conducted at Perry Point Department of Veterans Affairs Medical Center, an institution providing both acute and chronic care. We hypothesized that if significant nosocomial transmission was occurring, seropositivity (as measured by enzyme-linked immunosorbent assay [ELISA]) would correlate with length of stay in the facility. Whether treated as a continuous or dichotomous variable, the ELISA results did not correlate significantly with length of stay even after adjustments were made for age, race, antibiotic use, gastrointestinal instrumentation, and diagnoses by using multiple-regression models. Age was found to be a significant risk factor for a higher ELISA optical density value. A history of chronic obstructive pulmonary disease was significantly protective among internal medicine ward patients in adjusted analysis; black race was a significant risk factor among psychiatry ward patients. Our results confirm the association of H. pylori infection with age but provide no indication that extended hospitalization is a risk factor for infection.     

Inverse association of farm milk consumption with asthma and allergy in rural and suburban populations across Europe

BACKGROUND: Dietary interventions as a means for atopy prevention attract great interest. Some studies in rural environments claimed an inverse association between consumption of farm-produced dairy products and the prevalence of allergic diseases, but current evidence is controversial. OBJECTIVE: To investigate whether consumption of farm-produced products is associated with a lower prevalence of asthma and allergy when compared with shop-purchased products. METHODS: Cross sectional multi-centre study (PARSIFAL) including 14,893 children aged 5-13 years from five European countries (2823 from farm families and 4606 attending Steiner Schools as well as 5440 farm reference and 2024 Steiner reference children). A detailed questionnaire including a dietary component was completed and allergen-specific IgE was measured in serum. RESULTS: Farm milk consumption ever in life showed a statistically significant inverse association with asthma: covariate adjusted odds ratio (aOR) 0.74 [95% confidence interval (CI) 0.61-0.88], rhinoconjunctivitis: aOR 0.56 (0.43-0.73) and sensitization to pollen and the food mix fx5 (cut-off level of >or=3.5 kU/L): aOR 0.67 (0.47-0.96) and aOR 0.42 (0.19-0.92), respectively, and sensitization to horse dander: aOR 0.50 (95% CI 0.28-0.87). The associations were observed in all four subpopulations and independent of farm-related co-exposures. Other farm-produced products were not independently related to any allergy-related health outcome. CONCLUSION: Our results indicate that consumption of farm milk may offer protection against asthma and allergy. A deepened understanding of the relevant protective components of farm milk and a better insight into the biological mechanisms underlying this association are warranted as a basis for the development of a safe product for prevention.     

Specific IgE to allergens in cord blood is associated with maternal immunity to Toxoplasma gondii and rubella virus

Background: Various studies have found reduced prevalences of atopic sensitization and atopic diseases in children previously exposed to infections or living conditions with a high microbial burden, such as the farming environment. Objective: We sought to determine the relationships of cord blood immunoglobulin E (IgE) with maternal health conditions before and during pregnancy. Methods: Pregnant women living in rural areas in five European countries were recruited in the third trimester of pregnancy. Information on maternal health during pregnancy was collected from maternity records and by questionnaires (n = 497). Specific IgE for inhalant and food allergens was assessed in cord blood and peripheral blood samples of the mothers. Results: Inverse associations of cord blood IgE to seasonal allergens with positive maternal records for Toxoplasma gondii (adjusted odds ratio = 0.37 [0.17–0.81]) and rubella virus (adjusted odds ratio = 0.35 [0.13–0.96]) were found. The previously described effect of prenatal farm exposure on IgE to seasonal allergens was partly confounded by a positive maternal record for T. gondii. The number of maternal siblings, maternal contact to cats during pregnancy or during her first year of life, predicted a positive maternal record for T. gondii. Conclusions: Maternal immunity to T. gondii and rubella may impact on atopic sensitization in the fetus. A positive T. gondii record explained the previously identified effect of prenatal farm exposure on IgE to seasonal allergens only to a minor extent.     

Helicobacter pylori infection in an urban African population

We have studied 221 adults drawn from an impoverished urban population with high human immunodeficiency virus (HIV) seroprevalence (35%) to determine the prevalence of gastroduodenal pathology and its relationship to serological markers of Helicobacter pylori virulence proteins and other potential environmental and immunological determinants of disease including HIV infection. Eighty-one percent were H. pylori seropositive, and 35% were HIV seropositive. Urban upbringing and low CD4 count were associated with a reduced likelihood of H. pylori seropositivity, as was current Ascaris infection, in keeping with recent evidence from an animal model. One hundred ninety-one adults underwent gastroduodenoscopy, and 14 had gastroduodenal pathology. Mucosal lesions were a major cause of abdominal pain in this population. While the majority of patients with gastroduodenal pathology (12 of 14) were seropositive for H. pylori, none were seropositive for HIV. Smoking was associated with increased risk of macroscopic pathology, and a history of Mycobacterium bovis BCG immunization was associated with reduced risk. Antibodies to H. pylori lipopolysaccharide were associated with pathology. HIV infection was associated with protection against mucosal lesions, suggesting that fully functional CD4 lymphocytes may be required for the genesis of gastroduodenal pathology.     

The effect of infectious burden on the prevalence of atopy and respiratory allergies in Iceland, Estonia, and Sweden

BACKGROUND: Epidemiologic reports on the effect of microbe exposure on the development of atopy and allergic asthma are inconsistent. OBJECTIVES: The study investigates the association between serologic markers of infections and occurrence of atopy, allergic asthma, and rhinitis among adults in Iceland, Sweden, and Estonia. METHODS: Individuals (n = 1249; mean age, 42 years) from Iceland, Sweden, and Estonia underwent a structured interview and blood sampling. Specific IgE was measured against 4 allergens, and IgG antibodies were measured against Helicobacter pylori, Toxoplasmosis gondii, hepatitis A virus, herpes simplex virus 1, Chlamydia pneumoniae, EBV, and cytomegalovirus. RESULTS: Nonatopic subjects more often had positive serology for Helicobacter pylori, herpes simplex virus 1, Chlamydia pneumoniae, and cytomegalovirus. Having a low number (相似文献   

Seropositivity to a major allergen of Anisakis simplex, Ani s 1, in dyspeptic patients with Helicobacter pylori infection: histological and laboratory findings and clinical significance

Previous studies have demonstrated a high prevalence of seropositivity to the Ani s 1 protein in dyspeptic patients with Helicobacter pylori infection, but it is not known whether this represents episodes of anisakiasis misdiagnosis or previous exposure to the parasite without clinical relevance. To investigate the clinical significance of seropositivity to the Ani s 1 protein, a cohort study was performed with 87 consecutive dyspeptic patients who were treated for H. pylori infection. Fourteen (16.5%) patients were seropositive for the Ani s 1 protein, which was associated with the consumption of uncooked fish (p 0.0002). There were no differences in histological findings between subjects seropositive or seronegative for Ani s 1, but seropositive patients had increased eosinophil and basophil leukocyte counts (p < 0.05). Anti-Ani s 1 IgE was associated with a lack of improvement in the group of patients with non-ulcer dyspepsia after successful eradication of H. pylori (p 0.016). Thus, in at least a subset of patients with H. pylori infection, seropositivity to Ani s 1 could have clinical relevance. In addition, these data highlight that only anisakiasis associated with severe allergic or gastric symptoms is currently being diagnosed.     

Evaluation of western blot CagA seropositivity in Helicobacter pylori-seropositive and -seronegative subjects

CagA seropositivity is an important risk factor for gastric adenocarcinoma and duodenal ulcer. However, CagA seropositivity is also found in Helicobacter pylori-seronegative subjects. Is CagA seropositivity in these subjects a sign of a past H. pylori infection, or does it represent a false-positive reaction? This study investigates the intensity of the CagA immune reaction and the variation in CagA seroprevalence with year of birth for 650 subjects belonging to the Malmo Preventive Medicine cohort. CagA and H. pylori seroprevalences were determined by Western blot analysis (Helicoblot 2.1) and enzyme-linked immunosorbent assay. The peak intensity of the CagA band was significantly lower in H. pylori-seronegative subjects than in those with concomitant H. pylori seropositivity. In H. pylori-seropositive subjects, peak CagA intensity had a bimodal distribution. The prevalence of CagA-seropositive but H. pylori-seronegative subjects increased successively and significantly with year of birth, in contrast to the prevalence of CagA-seropositive and H. pylori-seropositive subjects, which decreased significantly. However, within H. pylori-seropositive and -seronegative subgroups, CagA seroprevalences were constant for different birth cohorts. If CagA seropositivity in H. pylori-seronegative subjects represents a past H. pylori infection, there must have been some mechanisms of eradication that were more common in younger subjects and that were of more importance than the presence of gastric atrophy and the longer duration and higher prevalence of H. pylori infection found in older subjects. Antibiotic treatment of H. pylori was not common practice at the time of enrollment. On the other hand, a false-positive reaction would be constant and independent of birth cohorts, as with the H. pylori-seronegative subgroup of our study. Peak CagA intensity in H. pylori-seronegative subjects corresponded to the lower part of the bimodal distribution of peak CagA intensity in H. pylori-seropositive subjects. We conclude that a major proportion of CagA seropositivity in H. pylori-seronegative subjects represents a false-positive reaction. Peak CagA intensity has a bimodal distribution in H. pylori-seropositive subjects. Low-intensity CagA seropositivity in H. pylori-seropositive subjects is indeterminate, representing both false-positive and true-positive reactions.     

IL-1B基因多态性和H.pylori感染与汉族人胃癌的相关性研究

目的：通过比较胃癌患者与匹配人群的幽门螺旋杆菌（Helicobacter pylori，H.pylori）感染率和IL-1B基因多态性，探讨IL-1B基因多态性是否增加H．pylori感染后胃癌发生的危险性。方法：采用聚合酶链反应-限制性片段长度多态性（Restriction fragment length polymorphism，RFLP）分析法检测胃癌低发区84例胃癌患者和84例与之性别、年龄匹配的普通人群的1L-1B基因多态性。采用酶联免疫吸附法（Enzyme—linked immunosorbent assay，ELISA）检测上述人群中的H.pylori感染率。结果：①胃癌患者IL-1B-511T／T基因型频率显著高于性别、年龄匹配的对照人群（P〈0．05），IL-1B-31T／T基因型频率在两组间无显著差异（P〉0．05）。84例胃癌患者的H.pylori感染率显著高于对照人群（P〈0．01）。胃癌患者H.pylori阳性感染者IL-1B-511 T／T基因型个体显著多于对照人群。结论：H.pylori感染者胃癌组织中IL-1B-511 T／T基因型为主，提示IL-1B-511 T／T基因型可能增加H.pylori感染后中国汉族人群发生胃癌的危险性，而IL-1B-31基因型与H.pylori感染后中国汉族人群胃癌发生无显著相关性。     

Infection with Helicobacter pylori, coronary heart disease, cardiovascular risk factors, and systemic inflammation: the Third National Health and Nutrition Examination Survey

BACKGROUND: Few data have been published on the association of variables of the metabolic syndrome and infection with Helicobacter pylori, a putative risk factor for cardiovascular morbidity, in large, representative samples of total populations. The null hypothesis was no association of prevalent infection with H. pylori with prevalent coronary heart disease (CHD), systemic inflammation, and variables associated with the metabolic syndrome in American men. DESIGN: Cross-sectional survey of a large national sample, the Third National Health and Nutrition Examination Survey. METHODS: Among men aged 40-74 years, the survey measured history of CHD, glycated hemoglobin percent, and concentrations of fasting serum glucose, insulin, triglycerides, HDL cholesterol, and C-reactive protein (CRP). RESULTS: Prevalence of infection with H. pylori increased with age. H. pylori infection was not correlated with serum CRP, prevalence of diagnosed diabetes mellitus, glycated hemoglobin percent, or other risk factors other than age. In diabetic men but not in all men, seropositivity was significantly associated with CHD prevalence. CONCLUSIONS: No consistent associations of H. pylon infection with diabetes prevalence or variables of the insulin resistance syndrome were found in American men aged 40-74 years. In diabetic men, H. pylori infection was associated with CHD prevalence.     

Helicobacter pylori serology in patients with coeliac disease and dermatitis herpetiformis.

AIMS: To investigate whether Helicobacter pylori infection or autoimmune gastritis is responsible for the reported increase in gastric pathology and abnormalities of gastric function in patients with coeliac disease and dermatitis herpetiformis (DH). METHODS: Serum H pylori IgG antibodies were assayed by enzyme linked immunosorbent assay and intrinsic factor antibodies by radioimmunoassay in 99 patients with coeliac disease and 58 patients with dermatitis herpetiformis from two geographic areas. RESULTS: H pylori positivity in patients with coeliac disease and dermatitis herpetiformis increased with age, reaching 50% and 70%, respectively, in patients over 50 years. The percentage H pylori seropositivity in coeliac disease did not differ from the percentage positivity observed in 250 similarly aged blood donors from the same geographic area (Leeds). Seropositivity in patients with dermatitis herpetiformis was not significantly different from the level of positivity observed in 98 age matched patients without dermatitis herpetiformis attending the same Edinburgh dermatology clinic. Only one patient with coeliac disease had positive intrinsic factor antibodies. H pylori seropositivity in Edinburgh control subjects under 30 years of age (41.9%) was significantly higher (p less than 0.03) than in Leeds controls (18%) of corresponding age. An increasing prevalence of H pylori seropositivity with age in coeliac disease and dermatitis herpetiformis paralleled that of the control groups. CONCLUSIONS: Gastritis in coeliac disease and dermatitis herpetiformis is largely caused by H pylori infection at a level that is no different from that of the general population. Any increase in the prevalence of gastritis in these two diseases might be caused by lymphocytic gastritis rather than pernicious anaemia.     

Cytomegalovirus seroprevalence in exposed and unexposed populations of hospital employees

The objective of this work was to compare the seroprevalence of cytomegalovirus in an unexposed and exposed population, both working in a hospital, and to study the occupational risk factors related to seropositivity, while taking personal risk factors into account. We conducted a cross-sectional study in a French hospital over a period of 12 months. The overall seroprevalence among the 550 subjects was 49.5%. The multivariate analysis showed that seropositivity was significantly associated with age (36–43 years: odds ratio [OR] = 1.7; 95% confidence interval [CI]: [1.1–2.8]) and working as a pediatric nurse’s aide (OR = 1.8; 95% CI: [1.1–2.8]). This study confirms the need to improve prevention procedures in the workplace, including screening, information, and hygiene rules.     

The protective effect of rural living against atopy in Mongolia

BACKGROUND: Farm environment in childhood protects against atopy. We investigated in a population-based study in Mongolia the effects of rural living and migration from rural to urban areas on the risk of atopy. METHODS: The screening study data of 9453 subjects, aged 10-60 years, were used for taking the sample for the clinical study in which 869 subjects were examined. Asthma, allergic rhinoconjunctivitis and sensitization were clinically defined and their risk factors analysed by logistic regression. RESULTS: The risks of allergic rhinoconjunctivitis [adjusted odds ratio (OR) 0.43, 95% confidence interval (CI) 0.19-0.98] and allergic sensitization (OR 0.26, 95% CI 0.13-0.55) were the lowest in subjects living in a village from birth and intermediate in subjects who had relocated from a village to a town (OR for rhinoconjunctivitis 0.68, 95% CI 0.36-1.27, OR for sensitization 0.62, 95% CI 0.35-1.12) compared with subjects living in a town from birth. Simultaneous exposure to herd animals and dung heating decreased the risk of atopy. Keeping animals was a risk-factor for asthma only in Ulaanbaatar city. CONCLUSIONS: Continuing farm exposure after childhood may be important in reducing the risk of atopy.     

Prevalence and risk-factors for Helicobacter pylori infection in urban and rural Beninese populations

In total, 446 healthy individuals (240 in urban and 206 in rural environments, respectively) were selected from 96 households, based on cluster sampling of residential location. Demographic, sociological and environmental data were collected by face-to-face interviews using a standard questionnaire. Infection with Helicobacter pylori was assessed by detection of anti-H. pylori IgG serum antibodies. The prevalence of H. pylori antibodies was 75.4% in the urban population and 72.3% in rural (village) residents (p 0.459). No association was found between infection and age, gender, education level, size of household, economic activity or source of drinking water. The infection rate was higher in children whose parents were both infected, and also in children whose mother was infected (p < 0.001). By logistic regression analysis, the density of occupation of sleeping accommodation (more than three persons sharing a room; 95% odds ratio (OR) = 9.82 (4.13-23.31), p < 0.001), and the mother's status within the household (95% OR = 3.85 (1.53-9.67), p 0.003), were independent predictors for H. pylori infection. The 74% seroprevalence of H. pylori infection found in healthy Beninese individuals is similar to that reported previously from other parts of sub-Saharan Africa. Family contact with infected persons and crowded living conditions were associated with increased risk of infection. These findings are consistent with intra-familial H. pylori transmission and suggest that improvement of living conditions should be protective against infection.     

Serum CagA antibodies in asymptomatic subjects and patients with peptic ulcer: lack of correlation of IgG antibody in patients with peptic ulcer or asymptomatic Helicobacter pylori gastritis.

AIM/BACKGROUND: Several studies have suggested that Helicobacter pylori which express CagA may be more virulent than those that do not, but limited populations have been studied to date. The aim of this study was to confirm and extend the association of CagA positive H pylori strains in a different geographical area and to a large, well defined patient population. METHOD: A validated ELISA for serum IgG to CagA was used to investigate the prevalence of CagA seropositivity in 100 patients with peptic ulcer compared with 77 with H pylori infection without ulcer disease in a North American population. The extent of antral and corpus inflammation and H pylori density in relation to CagA seropositivity in 40 subjects with H pylori infection were assessed semiquanitatively. All studies were carried out in a coded and blinded manner. RESULTS: The prevalence of serum IgG CagA antibodies was higher in H pylori infected patients with ulcer (59%) compared with healthy H pylori infected volunteers (44%), but the difference was not significant. In contrast, the titre of serum IgG anti-CagA antibodies was higher among the seropositive subjects without ulcer disease, but again the difference was not significant. Comparison of histological features between asymptomatic individuals with H pylori infection in relation to CagA IgG antibody status revealed no differences in infiltration with acute inflammatory cells, H pylori density, or gastritis index. There was no relation evident between the degree of polymorphonuclear cell infiltration and the serum IgG antibody titre to CagA. Mononuclear cell infiltration in the antrum, but not the corpus, was greater in those with CagA IgG compared with those without (median score 5 v 3). CONCLUSIONS: A right association between the presence or titre of serum IgG to CagA and peptic ulcer disease, greater H pylori density or infiltration of the mucosa with acute inflammatory cells could not confirmed in a North American population. Perhaps geographical differences in the prevalence of circulating H pylori strains are responsible for the discrepant results reported.