Volatile and semi-volatile organic compounds of respiratory health relevance in French dwellings.

Over the last decades, the prevalence of childhood respiratory conditions has dramatically increased worldwide. Considering the time spent in enclosed spaces, indoor air pollutants are of major interest to explain part of this increase. This study aimed to measure the concentrations of pollutants known or suspected to affect respiratory health that are present in dwellings in order to assess children's exposure. Measurements were taken in 150 homes with at least one child, in Brittany (western France), to assess the concentrations of 18 volatile organic compounds (among which four aldehydes and four trihalomethanes) and nine semi-volatile organic compounds (seven phthalates and two synthetic musks). In addition to descriptive statistics, a principal component analysis (PCA) was used to investigate grouping of contaminants. Formaldehyde was highly present and above 30 µg/m(3) in 40% of the homes. Diethyl phthalate, diisobutyl phthalate, and dimethylphthalate were quantified in all dwellings, as well as Galaxolide and Tonalide. For each chemical family, the groups appearing in the PCA could be interpreted in term of sources. The high prevalence and the levels of these compounds, with known or suspected respiratory toxicity, should question regulatory agencies to trigger prevention and mitigation actions.

Asthma attacks and deprivation: gradients in use of mobile emergency medical services.

BACKGROUND: To test whether rates of emergency telephone calls for asthma attacks are associated with contextual socioeconomic deprivation in the Strasbourg metropolitan area (France). METHODS: Two mobile emergency medical service networks provided all data for 2000-2005 about emergency calls for asthma attacks, georeferenced by census block. Contextual deprivation was measured for each census block by a composite index, constructed by principal component analysis. Emergency call rates were calculated for each census block and for different age groups. Empirical Bayesian smoothing was used to reduce the instability of outlying rates. RESULTS: Positive spatial autocorrelation was detected in both the health and the socioeconomic datasets. In all age groups, rates of calls for asthma attacks increased linearly with deprivation. Correlation coefficients between these two factors varied according to age group: 0.53 for the group aged 0-9 years, 0.46 for 10-19 years, 0.65 for 20-39 years, 0.70 for 40-64 years, 0.68 for 65 and older, and 0.77 for the age-standardised incidence ratio. These correlation coefficients were highly significant (p<0.01), even after spatial autocorrelation was taken into account. CONCLUSION: The socioeconomic gradients observed are consistent with those observed for severe forms of asthma and asthma hospitalisations in Western countries.

Estimation of the contact rate in a seasonal SEIR model: application to chickenpox incidence in France.

This work was an attempt at analysing the seasonal pattern of varicella epidemics in France by fitting a susceptibles-exposed-infectives-recovered (SEIR) model with a periodic contact rate function to weekly chickenpox incidence data collected over the period 1991 to 1996. The contact rate was assumed to be either a continuous, or a piecewise constant, periodic function. Both assumptions gave a reasonable fit to the data and yielded estimates of the incubation and infectious periods that were consistent with values derived on clinical or serological grounds. Seasonal fluctuation of the estimated contact rate function was likely to reflect the impact of school holidays on chickenpox diffusion among schoolchildren.

Impact on immunization of seasonal cycle of chickenpox.

The objective of this work was to study the effect of incorporating a seasonal term in a compartmental age-structured theoretical transmission model, on the performance of vaccination strategies for chickenpox. The epidemiologic parameters are taken from data or are based on a review of literature. We used a realistic age-structure model (RAS): It is a model that incorporate both age and seasonal structure. The seasonality was introduced in the model with the addition of sinusoidal forcing term. This seasonal term varies between 0 and 1. From a susceptible/exposed/infectious/removed (SEIR) model with or without age-structure, the pattern of time series is dramatically modified after introducing a seasonal term. This dynamic ends to the transition to chaos. Regarding the evaluation of vaccination strategies, the results of the model without seasonality may be disturbed when the seasonality is introduced, especially during the first 30 years of simulations.

Epidemiology of chickenpox in France (1991-1995).

STUDY OBJECTIVES: To decide whether a mass immunisation against chickenpox should be or should not be organised, it is important to have up to date data on the disease and to have baseline data to further assess a mass immunisation strategy, if any. DESIGN: Recent chickenpox epidemiology (age and sex distribution, seasonal dynamic and complications) in France are reviewed. SETTING: The system works with about 500 Sentinelle general practitioners (SGPs) and has provided surveillance of frequent communicable diseases in continental France since 1984. PARTICIPANTS: The data were collected by the computerised Sentinelle system. The Sentinelle system uses a videotex server that allows information exchange, data entry, and synthetic return of information. Chickenpox was defined as a sudden onset of typical skin eruption with pruritus, leaving scabs and associated with moderate fever. For each reported case, the SGP gave information on the age of the patient, sex, prevailing childcare for the children, contacts and complications (skin superinfections, lower and upper respiratory infections, conjunctivitis and corneal infections, nervous system injuries, stomatitis and others). Spectral analysis was used to detect cyclical patterns. MAIN RESULTS: Between 1991 and 1995, 15,817 cases of chickenpox were reported and provided the basis for the analysis. The yearly national incidence was 1.0-1.35 cases per 100 inhabitants. A pronounced annual periodicity of the incidence was observed and confirmed by spectral analysis. Ninety two per cent of chickenpox cases occurred in children under 14 years of age with about 5% being under one. Complications were reported in 2% of the cases. Common complications reported were skin superinfections, lower and upper respiratory tract infections. However, 21 cases out of 318 complications were nervous system injuries including six encephalitis or cerebellar ataxia. All these cases recovered completely. CONCLUSIONS: Chickenpox is usually a benign childhood disease. This study affords up to date observations on the disease in France. A large panel of complications has been reported. This paper provides the first attempt to describe the epidemiology of chickenpox in France.

A mathematical model for the European spread of influenza.

Following a study modelling the geographical spread of influenza in France, on the basis of population movements through the use of railroad data, we applied the same methodology on a European scale. We simulated an epidemic within a network of 9 European cities (Amsterdam, Berlin, Budapest, Copenhagen, London, Madrid, Milano, Paris, Stockholm), only taking into account regular between-cities air transport. Transportation data were obtained from the International Civil Aviation Organization (1991). The theoretical results show that the time lag for action is probably short (less than one month) after the first detection of an epidemic focus.