Thunderstorm-associated asthma in an inland town in south-eastern Australia. Who is at risk?
The aim of the study was to characterize patients at risk of asthma exacerbation during spring thunderstorms and identify potential measures to ameliorate the impact of those events. A case-control study was conducted among patients aged 7-60 yrs, who attended Wagga Hospital (NSW, Australia) for asthma during the period of 1 June 1997 to 31 October 1997. One hundred and eighty-three patients who attended on 30 and 31 October 1997 were the cases and the remaining 121 patients were the controls. Questionnaire data were obtained from 148 (81%) cases and 91 (75%) controls. One hundred and thirty-eight (95%) cases who attended during the thunderstorm gave a history of hayfever prior to the event compared to 66 (74%) controls who attended at other times (odds ratio (OR) 6.01, 95% confidence interval (CI) 2.55-14.15); 111 (96%) cases were allergic to rye grass pollen compared to 47 (64%) controls (OR 23.6, 95% CI 6.6-84.3). Among subjects with a prior diagnosis of asthma (64% cases and 82% controls), controls (56%) were more likely to be taking inhaled steroids at time of the thunderstorm than cases (27%, OR 0.3, 95% CI 0.16-0.57). History of hayfever and allergy to rye grass are strong predictors for asthma exacerbation during thunderstorms in spring. The lower rate of inhaled steroid use in thunderstorm cases suggests that this treatment may be effective in preventing severe attacks during thunderstorms. (+info)
Weather and nodule mediated variations in delta 13C and delta 15N values in field-grown soybean (Glycine max L.) with special interest in the analyses of xylem fluids.
The nodulating soybean (Enrei) and its non-nodulating mutant (EN 1282) were grown in outdoor plots for 2 years (1994: extraordinary dry, high temperature, 1995: ordinary year). Carbon and nitrogen accumulation, delta 13C and delta 15N values in plant parts and xylem fluids and delta 15N values in the water-extractable soil N were analysed throughout the growing period. Plant growth in 1994 was rapid during the early growth stages, but no pods were produced. In 1995, plant growth was normal and pods were formed. The delta 13C values of the leaves were less negative in 1994 than in 1995 and the nodulated plants showed less negative delta 13C values than non-nodulated plants in both years. The delta 13C values of the leaves during the vegetative phase were positively correlated to the leaf N concentrations. Leaf N concentrations in their turn were influenced by nodulation and weather conditions and/or soil available N. The delta 15N values in the plants and xylem fluids were lower in the nodulated soybean than in non-nodulated soybean in both years, and estimates of the contribution of N2 fixation in nodulated plants based on plant top delta 15N values were 7-14% in 1994 and 37-63% in 1995. The delta 13C values of xylem fluids did not differ between nodulated and non-nodulated plants. Thus, the expected contribution by phosphopenolpyruvate carboxylase-mediated CO2 fixation in the root nodules to plant C-incorporation could not have been significant. (+info)
Cholera dynamics and El Nino-Southern Oscillation.
Analysis of a monthly 18-year cholera time series from Bangladesh shows that the temporal variability of cholera exhibits an interannual component at the dominant frequency of El Nino-Southern Oscillation (ENSO). Results from nonlinear time series analysis support a role for both ENSO and previous disease levels in the dynamics of cholera. Cholera patterns are linked to the previously described changes in the atmospheric circulation of south Asia and, consistent with these changes, to regional temperature anomalies. (+info)
An overview of remote sensing and geodesy for epidemiology and public health application.
The techniques of remote sensing (RS) and geodesy have the potential to revolutionize the discipline of epidemiology and its application in human health. As a new departure from conventional epidemiological methods, these techniques require some detailed explanation. This review provides the theoretical background to RS including (i) its physical basis, (ii) an explanation of the orbital characteristics and specifications of common satellite sensor systems, (iii) details of image acquisition and procedures adopted to overcome inherent sources of data degradation, and (iv) a background to geophysical data preparation. This information allows RS applications in epidemiology to be readily interpreted. Some of the techniques used in geodesy, to locate features precisely on Earth so that they can be registered to satellite sensor-derived images, are also included. While the basic principles relevant to public health are presented here, inevitably many of the details must be left to specialist texts. (+info)
Association of school absence with air pollution in areas around arterial roads.
Association of school absence with air pollution from suspended particulate matter (SPM) and nitrogen dioxide was analyzed in areas around arterial roads for five years, from 1993 to 1997. The prevalence of absence was calculated using the data for school absence in two schools around arterial roads, one of which is near a crossing (Sch.A), and the other is adjacent to an arterial road (Sch.B). Although the results from annual correlation analyses did not indicate common findings for five years or in the two schools, the prevalence of absence correlated positively with SPM, nitrogen dioxide, or relative humidity, and negatively with atmospheric temperature. As the results from multiple regression analyses, atmospheric temperature in Sch.A was adopted as the optimum explanatory variable, whereas SPM and relative humidity were considered in Sch.B. Odds ratios for the prevalence of absence to SPM were elevated and were significant in Sch.B, when using a quintile method. The other odds ratios for the air pollutants were not significant, but exceeded 1. When the data were classified by day of the week, significant associations of the prevalence of absence were observed with atmospheric temperature in Sch.A and with SPM in Sch.B. The slope of the regressive equations by day of the week became steeper with the day in Sch.B. SPM was weakly associated with the prevalence of absence in Sch.A and was closely associated in Sch.B according to the optimum variables selected from the multiple regression analyses by day of the week. (+info)
Effects of naturally-occurring acid fog on inflammatory mediators in airway and pulmonary functions in asthmatic patients.
Floating fog occurs every summer in Kushiro City in Japan, and the annual average of fog water pH in the past 4 years has been under 5.0. We previously reported that epidemiologically fog was the most important positive factor contributing to increased hospital visits of asthmatic patients compared with other meteorological values and air pollutants. This study aimed to investigate the mechanism of the effects of naturally-occurring acid fog on asthmatic patients. We compared pulmonary functions and inflammatory mediators in induced sputum between the foggy (July 1995) and the non-foggy (May 1996) season, and assessed airway responsiveness to hypo-osmolar aerosol. Forty-four out of 118 asthmatic patients of Kushiro City residents participated, pulmonary function tests were completed in 36 patients, and sputum data were available in 26 patients in both seasons. Percent forced expiratory volume in 1 sec (FEV1) was significantly (P< 0.05) decreased, and % peak expiratory flow rate (PEFR) had a trend to decrease in the foggy season more than in the non-foggy, and sputum eosinophil cationic protein (ECP) and interleukin (IL)-8 were higher in the foggy season but not significantly. A moderate inverse correlation was revealed between sputum ECP and %PEFR in the foggy season (r= -0.55, P<0.005). Subjects were divided into two groups according to the best PEFR; one had >10% lower PEFR levels in the foggy season than in the non-foggy season (Group A, n = 7), the remainder did not (Group B, n = 19). In group A, sputum ECP was significantly increased (P< 0.01) in the foggy season, but there were no changes in IL-8 and prostaglandin D2. Ultrasonic nebulized distilled water provocation test revealed no differences between group A and B. These results suggested that eosinophilic inflammation rather than hypo-osmolar effect of fog might contribute to respiratory deterioration by inhalation of naturally-occurring acid fog. (+info)
Do respiratory epidemics confound the association between air pollution and daily deaths?
Daily deaths are associated with air pollution. This association might be con*hhy;founded by uncontrolled risk factors. In order to estimate the potential confounding caused by respiratory epidemics of the association between air pollution and health effects, a time series study of air pollution and daily deaths was carried out. Daily records of deaths for all ages were obtained from five US cities: Chicago, IL; Detroit, MI; Minneapolis, MN; Pittsburgh, PA; and Seattle, WA. Daily levels of particles with a 50% cut-off aerodynamic diameter of 10 microm (PM10) and weather measurements were obtained. City-specific analysis was carried out using Poisson regression, adjusting for time trend, ambient temperature, dew point, barometric pressure and day of the week. A cubic polynomial was used for each epidemic period (> or =10 days of excessive pneumonia hospital admissions), and a dummy variable was used to control for isolated epidemic days. A 10-microg x m(-3) increase in PM10 concentration (lag 0-1) was associated with increased daily deaths in Chicago (0.81%, 95% confidence internal (CI) 0.54-1.09); Detroit (0.87%, 95% CI 0.60-1.15), Minneapolis (1.34%, 95% CI 0.78-1.90), Pittsburgh (0.84%, 95% CI 0.51-1.18) and Seattle (0.52%, 95% CI 0.11-0.94). When controlling for respiratory epidemics, small decreases in the PMlo effect were observed (Chicago 9%, Detroit 11%, Minneapolis 3%, Pittsburgh 5%, and Seattle 15%). The overall effect of PM10 concentration was 0.85% (95% CI 0.60-1.10) per 10 microg x m(-3) before controlling for epidemics and 0.78% (95% CI 0.51-1.05) after. This study showed that the association between air pollution and daily deaths is not due to failure to control for influenza or pneumonia epidemics. (+info)
Malaria early warning in Kenya.
Kenya displays large spatiotemporal diversity in its climate and ecology. It follows that malaria transmission will reflect this environmental heterogeneity in both space and time. In this article, we discuss how such heterogeneity, and its epidemiological consequences, should be considered in the development of early warning systems for malaria epidemics. (+info)