Description of two waterborne disease outbreaks in France: a comparative study with data from cohort studies and from health administrative databases.

Waterborne disease outbreaks (WBDO) of acute gastrointestinal illness (AGI) are a public health concern in France. Their occurrence is probably underestimated due to the lack of a specific surveillance system. The French health insurance database provides an interesting opportunity to improve the detection of these events. A specific algorithm to identify AGI cases from drug payment reimbursement data in the health insurance database has been previously developed. The purpose of our comparative study was to retrospectively assess the ability of the health insurance data to describe WBDO. Data from the health insurance database was compared with the data from cohort studies conducted in two WBDO in 2010 and 2012. The temporal distribution of cases, the day of the peak and the duration of the epidemic, as measured using the health insurance data, were similar to the data from one of the two cohort studies. However, health insurance data accounted for 54 cases compared to the estimated 252 cases accounted for in the cohort study. The accuracy of using health insurance data to describe WBDO depends on the medical consultation rate in the impacted population. As this is never the case, data analysis underestimates the total number of AGI cases. However this data source can be considered for the development of a detection system of a WBDO in France, given its ability to describe an epidemic signal.

No increase in drug dispensing for acute gastroenteritis after Storm Klaus, France 2009.

During the night of 23-24 January 2009, Storm Klaus hit south-western France and caused power outages affecting 1,700,000 homes and stopping numerous pumping and drinking water disinfection systems. In France, medicalized acute gastroenteritis (MAGE) outbreaks are monitored by analysing the daily amount of reimbursements of medical prescriptions, registered in the French National Health Insurance database, at the 'commune' administrative level. As AGE is suspected to be associated with perturbations to water supply systems as well as power outages, Storm Klaus provided an opportunity to test its influence on the incidence of MAGE in the communes of three affected French departments (administrative areas larger than communes). The geographical exposure indicator was built by using the mapping of the water distribution zones, the reported distribution/production stoppages and their duration. Irrespective of exposure class, a relative risk of MAGE of 0.86 (95% confidence 0.84-0.88) was estimated compared with the 'unexposed' reference level. Although these results must be considered with caution because of a potential marked decrease in global medical consultation probably due to impassable roads, they do not suggest a major public health impact of Klaus in terms of increased MAGE incidence.

Cold spells and health: prevention and warning.

OBJECTIVES: The aim of this paper is to point out the kinds of measures that should be implemented to protect the population from the health effects of cold and when to put them into action, thanks to meteorological thresholds. STUDY DESIGN: The authors used pertinence criteria to determine if an alert system would be relevant to trigger preventive measures. METHODS: The pertinence criteria included ability to prevent health impact through specific measures, simplicity, reactivity, adaptability, and the possibility to find indicators able to predict a health impact of cold. This was investigated in two pilot cities, using time-series models to identify mortality-relevant thresholds, if any. RESULTS: Short-term measures are mainly directed at homeless people while actions focussing on the general population are mostly limited to providing advice on how to protect oneself from exposure to cold. The main long-term measures are housing insulation and heating. Combined minimum and maximum temperatures are the best indicators to predict the health impact of cold temperatures on mortality. Associated optimal thresholds for action in Paris were -9 °C and -2 °C for minimum and maximum temperatures respectively while thresholds in Marseille were -3 °C and +4 °C. When both thresholds are reached in a given city, the risk of excess mortality is greater than 15%. CONCLUSION: Simple meteorological indicators could be used to improve the detection of dangerous cold episodes and promote communication. Nevertheless, long-term housing improvement and financial aids for home heating remain the best means to prevent the adverse effects of cold weather on community health.

How can a climate change perspective be integrated into public health surveillance?

OBJECTIVES: Climate change may be considered as a key factor for environmental change, exposure to health risks and pathogens, consequently impairing the state of health among populations. Efficient health surveillance systems are required to support adaptation to climate change. However, despite a growing awareness, the public health surveillance sector has had very little involvement in the drafting of adaptation plans. This paper proposes a method to raise awareness about climate change in the public health community, to identify possible health risks and to assess the needs for reinforced health surveillance systems. METHODS: A working group was set up comprising surveillance experts in the following fields: environmental health; chronic diseases and; infectious diseases. Their goal was to define common objectives, to propose a framework for risk analysis, and to apply it to relevant health risks in France. RESULTS: The framework created helped to organize available information on climate-sensitive health risks, making a distinction between three main determinants as follows: (1) environment; (2) individual and social behaviours; and (3) demography and health status. The process is illustrated using two examples: heatwaves and airborne allergens. CONCLUSION: Health surveillance systems can be used to trigger early warning systems, to create databases which improve scientific knowledge about the health impacts of climate change, to identify and prioritize needs for intervention and adaptation measures, and to evaluate these measures. Adaptation requires public health professionals to consider climate change as a concrete input parameter in their studies and to create partnerships with professionals from other disciplines.

Syndromic surveillance of acute gastroenteritis based on drug consumption.

Since 1998, the French Health Insurance (NHI) system had established a national database in order to reimburse drug prescriptions. These electronical data are a considerable potential source for syndromic surveillance because of their exhaustive and regular updates. The aim of this study was to develop a method to identify acute gastroenteritis (AG) cases from drug reimbursements of the NHI database. The algorithm aimed at discriminating AG from other pathologies was determined from a sample of 206 AG prescriptions and 351 non-AG prescriptions collected in five pharmacies. The AG case identification was mainly based on the lag time between the prescription and delivery day, the occurrence of non-AG case-specific drugs, AG case-specific drug associations and treatment duration. The discriminant algorithm led to a sensitive and specific indicator of medically treated cases of AG with a time-spatial resolution power which met the need for waterborne AG surveillance.

Short-term effects of air pollution on mortality in the cities of Rouen and Le Havre, France, 1990-1995.

In this study, the authors examined the short-term effects of ambient air pollution on mortality across 2 French cities: Rouen and Le Havre. In Poisson regression models, which controlled for day-of-week effects, the authors used nonparametric smoothing to control for temporal trend, weather, and influenza epidemics. In Rouen, an interquartile range increase of 60.5-94.1 microg/m3 of ozone was associated with an increase of 4.1% (95% confidence interval = 0.6, 7.8) of total mortality. Daily variations in sulfur dioxide (interquartile range increase = 17.6-36.4 microg/m3) were also associated with an 8.2% increase (95% confidence interval = 0.4, 16.6) in respiratory mortality. An increase of 6.1% (95% confidence interval = 1.5, 10.9) of cardiovascular mortality was also observed with an interquartile range increase of nitrogen dioxide (i.e., 25.3-42.2 microg/m3). With respect to Le Havre, an interquartile range increase in daily levels of sulfur dioxide (11.3-35.6 microg/m3) was associated with an increase of approximately 3% (95% confidence interval = 0.8, 5) of cardiovascular mortality. For particulate matter less than or equal to 13 microm in diameter (interquartile increase = 21.5, 45.4 microg/m3), an increase of 6.2% (95% confidence interval = 0.1, 12.8) was observed. The estimates of pollutant effects and their standard deviations were slightly affected by the degree of smoothing temporal variations in this study. When low collinearity was present, the 2-pollutant models provided acceptable estimates of pollutant effects. They suggested that the ozone effect was independent of the Black Smoke effect, and that the effects of sulfur dioxide and nitrogen dioxide were unlikely to be confounded by ozone concentrations. However, high collinearity leads to large estimates of the pollutant coefficient variances and, therefore, leads to inaccurate estimates of pollutant effects. The analysis of the contributory effects of different pollutant mixtures requires further investigation in those instances in which high collinearity between pollutants is present.

In situ measurement and statistical modelling of Escherichia coli decay in small rivers.

Numerous studies have been carried out on the environmental factors associated with the decay of faecal bacteria in open (fresh or marine) waters. The present study aimed at understanding the fate of bacteria in small streams (flow <20 m3 s(-1)) for which there is a lack of knowledge. An original in situ protocol was developed for measuring the die-off of Escherichia coli (E. coli) from wastewater treatment plants. Based upon 80 values of the decay first-order parameter (K or its inverse T90), collected from five rivers in Normandy (France), a median T90 of 10 h and a minimal T90 of 1.3 h were obtained. K was then modelled as a linear function of variables made up from flow, water temperature and suspended particulate matter (SPM). The set of significant co-variables did not include light indicators. E. coli decay is inversely related to the river flow and it becomes highly significant below 0.3 m3 s(-1). The positive effect of small flows on die-off is increased by water temperature over 15 degrees C, whereas it could be reduced by SPM. The major co-variable of the model (p < 10(-9)) is an empiric composite variable integrating the effect of flow and temperature that explains more than 40% of the variance of K. We interpreted this as an expression of predation by benthic micro-grazers which could be the main cause of E. coli die-off in small streams in temperate countries.

Air pollution and respiratory drug sales in the City of Le Havre, France, 1993-1996.

The aim of this study is to evaluate ambulatory respiratory drug sales data as health indicators for the short-term effects of ambient air pollution in the city of Le Havre. Daily respiratory drug sales data were crossed with daily ambient air concentrations of sulfur dioxide (SO2), nitrogen dioxide (NO2), and black smoke (BS) using an autoregressive Poisson regression model adjusting for time trends, seasonal variations, influenza epidemics, and weather. Relative risks (RR) were expressed for an increase of two standard deviations above the mean of each pollutant. Respiratory drug sales were associated with most pollutants studied with lags varying from 1 to 9 days. For daily mean concentrations of BS, RR = 1.037 (95% confidence interval (CI) 1.009-1.066) for lag 1 and RR = 1.052 (95% CI 1.023-1.081) for lag 8. For daily mean concentrations of N02, RR = 1.033 (95% CI 1.001-1.066) for lag 1 and RR = 1.046 (95% CI 1.014-1.079) for lag 8. RR observed with a daily 1 h maximum of SO2 were RR= 1.027 (95% CI 1.004-1.051) for lag 3 and RR= 1.032 (95% CI 1.009-1.056) for lag 9. Our study concludes that ambulatory respiratory drug sales data could be useful for epidemiological surveillance of air pollutant health effects.

Assessment of the marker value of various components of the coli-aerogenes group of Enterobacteriaceae and of a selection of Enterococcus spp. for the official monitoring of drinking water supplies.

The traditional indicators Escherichia coli (in practice currently, though ecologically inaccurately, represented by 'thermotolerant coliforms' at 44 degrees C) and Enterococcus spp. proved to be suitable for the diagnosis of heavy and frequent faecal pollution observed in potentially dangerous waters, especially those originating from karstic aquifers. On the other hand, natural and treated waters, slightly and inconsistently contaminated, occasionally showed a variable Gram-negative flora, difficult to classify by routine tests. In that case, complete identification of isolates may be necessary to ensure a valid decision on the potability of the supply. At any rate some of the Enterobacteriaceae contained in the 'faecal coliform' group and many other 'coliforms', distinct from E. coli, lack sanitary significance although their presence at certain levels may indicate inadequate disinfection, hiatuses in the integrity of the distribution system or both.

[Licit and illicit drug consumption in the school environment. Results of a cross-sectional epidemiologic survey carried out among 663 high school students in Le Havre]. / Consommation de drogues licites et illicites en milieu scolaire. Résultats d'une enquête épidémiologique transversale réalisée auprès de 663 collégiens du Havre.

A cross-sectional epidemiologic study was undertaken in 1988 in the city of Le Havre, in order to study the licit and illicit drug consumption of adolescents attending high schools. The regular consumption of alcohol was higher in boys (9.2% vs 5.8%) whereas girls smoked more (16.4% vs 12.5%). In the group (4.2%) of every day drinkers, cider was the first alcoholic beverage used. One of 5 adolescents had been drunk at least once in 6 months, those over 15 years of age being involved twice as often as the youngest (28.2% vs 14.1%). The use of neuropsychotropic drugs was independent of sex, age and performance in school. Typological classification according to patterns of alcohol and drug consumption identified 4 groups of adolescents: the excessive consumers (3.6%), the moderate (25.6%), the abstainers (58.1%) and the consumers of psychotropic drugs (12.7%). The distribution of adolescents into these classes was influenced by age and, to a lesser extent, by school performance.