Farmers and their environment: protective influences of the farming environment against the development of allergies.

Compared with other population groups, the way of life of farmers can be viewed as being similar to that of our ancestors. The settled continuation of generations within certain critical geographical and environmental conditions requires a special local network of knowledge and experience. The immune system provides protection against microbes and their toxins. Each strong reaction impedes an active adaptation. Allergy is therefore a harmful intolerance and represents one of many different paradoxes. The aim of this chapter is to demonstrate some of the interactions of tolerance and adaptation from a historical background.

Vaccinated students with negative enzyme immunoassay results show positive measles virus-specific antibody levels by immunofluorescence and plaque neutralisation tests.

BACKGROUND: The prevalence of measles antibodies was investigated by an enzyme immunoassay (EIA) in students aged 14 every year since 1996 in a Swiss municipality. This region has wide measles vaccine coverage (first dose > or = 95%, second dose > or = 65%) without any reported measles outbreaks since 20 years. In 2003 and 2004, in contrast to previous years, surprisingly many negative results (33% and 54%, respectively) were observed. OBJECTIVES: To corroborate the measles antibody values by different methods. STUDY DESIGN: Serum samples from 101 students with known vaccination status were available. Sera with equivocal and negative results obtained by two different EIAs were retested by indirect immunofluorescence test (IFT) and plaque neutralisation test (PNT). RESULTS: Retesting by IFT showed a positive result in 17/21 sera (81%) and retesting by PNT indicated that 46/49 sera (94%) were positive; the three sera with negative PNT result were from unvaccinated individuals. Only 3/96 vaccinated students showed measles antibodies below the putative protective level of 0.2 IU/ml after retesting by PNT. CONCLUSIONS: Negative EIA results should be interpreted with caution in a widely vaccinated population without booster by circulation of wild viruses. Retesting by IFT or PNT is recommended.

Decline of ambient air pollution levels and improved respiratory health in Swiss children.

The causality of observed associations between air pollution and respiratory health in children is still subject to debate. If reduced air pollution exposure resulted in improved respiratory health of children, this would argue in favor of a causal relation. We investigated whether a rather moderate decline of air pollution levels in the 1990s in Switzerland was associated with a reduction in respiratory symptoms and diseases in school children. In nine Swiss communities, 9,591 children participated in cross-sectional health assessments between 1992 and 2001. Their parents completed identical questionnaires on health status and covariates. We assigned to each child an estimate of regional particles with an aerodynamic diameter < 10 microg/m3 (PM10) and determined change in PM10 since the first survey. Adjusted for socioeconomic, health-related, and indoor factors, declining PM10 was associated in logistic regression models with declining prevalence of chronic cough [odds ratio (OR) per 10-microg/m3 decline = 0.65, 95% confidence interval (CI), 0.54-0.79], bronchitis (OR = 0.66; 95% CI, 0.55-0.80), common cold (OR = 0.78; 95% CI, 0.68-0.89), nocturnal dry cough (OR = 0.70; 95% CI, 0.60-0.83), and conjunctivitis symptoms (OR = 0.81; 95% CI, 0.70-0.95). Changes in prevalence of sneezing during pollen season, asthma, and hay fever were not associated with the PM10 reduction. Our findings show that the reduction of air pollution exposures contributes to improved respiratory health in children. No threshold of adverse effects of PM10 was apparent because we observed the beneficial effects for relatively small changes of rather moderate air pollution levels. Current air pollution levels in Switzerland still exceed limit values of the Swiss Clean Air Act; thus, children's health can be improved further.

Helicobacter pylori infection in Swiss adolescents: prevalence and risk factors.

OBJECTIVE: This investigation sought to study the influence exerted by demographic and socioeconomic factors on the prevalence of infection in adolescents living in Switzerland. DESIGN: Epidemiological study spanning 3 years. METHODS: We included 196 15- to 16-year-old adolescents from a north-eastern Swiss city in our study, recruited by the school health service during a medical check-up in the years 1999, 2000 and 2001. infection was detected by ELISA using 2nd generation anti- IgG antibodies. Demographic and socioeconomic data were collected by questionnaire. RESULTS: infection was found in 19 of the 196 (9.7%) tested adolescents. tested positive in, respectively, 13 (7.3%) of the 176 natives and six (30%) of the 20 (P = 0.01 chi-squared) subjects from foreign countries. infection was significantly highly correlated with demographic factors but did not correlate with most of the socioeconomic factors. CONCLUSION: The rate of infection among Swiss adolescents is one of the lowest in Europe. Nevertheless, an important disparity is evident between the rate of infection observed in the native population and that among immigrants. High living standards available to the majority of the population may explain the minor influence of socioeconomic factors on infection in our country.