Incidence of all-cause adult community-acquired pneumonia in primary care settings in France.

OBJECTIVES: To estimate the incidence of all-cause outpatient community-acquired pneumonia (CAP) in adults in France from a national prospective observational study of CAP management in general practice (CAPA). METHODS: Patients aged over 18 years presenting with signs or symptoms indicative of CAP associated with recent onset of unilateral crackles on auscultation and/or a new opacity on chest X-ray were included in the CAPA study. An ancillary survey (AIMSIS) aiming at identifying family physicians' difficulties in including patients and at collecting their opinion on the use of an electronic case report form, determined the number of non-included eligible patients. A three-step analysis was then performed, including computation of the total number of eligible patients, adjustment for seasonality, and extrapolation to the French FP population using indirect standardization to adjust for differences in characteristics between CAPA FPs and French FPs. RESULTS: Between September 2011 and July 2012, 267 (63%) CAPA investigators included 886 CAP patients. Most patients presented with mild CAP. The rates of hospitalization and one-month case fatality were 7% and 0.3%, respectively. Data from 336 (79%) AIMSIS investigators identified 641 additional patients and estimated at 234,023 the number of CAP patients per year (incidence of 4.7 per 1000 persons per year). CONCLUSIONS: Using a pragmatic case definition of CAP patients, this study estimated an incidence of 4.7 per 1000 persons per year that is in the lower half of the range of estimated incidences reported in primary care settings in industrialized countries.

Virtual surveillance of communicable diseases: a 20-year experience in France.

Inserm has developed, since 1984, an information system based on a computer network of physicians in France. It allows for constitution of large databases on diseases, with individual description of cases, and to explore some aspects of the mathematical theory of communicable diseases. We developed user-friendly interfaces for remote data entry and GIS tools providing real-time atlas of the epidemiologic situation in any location. The continuous and ongoing surveillance network is constituted of about 1200 sentinel voluntary and unpaid investigators. We studied their motivation, reasons for either withdrawal or compliance using survival analyses. We implemented early warning systems for outbreak detection and for time-space forecasting. We conducted epidemiological surveys for investigating outbreaks. Large available time and space series allowed us to calibrate and explore synchronism of influenza epidemics, to test the assumption of panmixing in susceptibles-infectious-removed type models and to study the role of closing school in influenza morbidity and mortality in elderly. More than 250 000 cases of influenza, 150 000 cases of acute diarrheas, 35,000 patients for whom HIV tests have been prescribed by general practitioners and 25,000 cases of chickenpox have been collected. Detection of regional influenza or acute diarrhea outbreaks and forecasting of epidemic trends three weeks ahead are currently broadcasted to the French media and published on Sentiweb on a weekly basis. Age-cohort-period models assessed field effectiveness of mass immunization strategies against measles and influenza in the country. Case-control studies with more than 1200 sets of cases of acute diarrheas and their matched controls showed the role of calicivirus and rotavirus as probable major causes of gastroenteritis during recurrent widespread outbreaks in winter in France. An age-specific model for chickenpox showed the probable role of children in disease transmission to their susceptible parents or grandparents. High level of synchronism between influenza epidemics has been demonstrated, either at a regional level (in France) or between France and the USA. The designation of our lab as a WHO collaborating center for electronic disease surveillance stimulates the development of global monitoring of diseases. We developed operational systems that are now available for the global monitoring of influenza (FluNet), and human and animal rabies (RABNET). Extension of electronic syndromic surveillance is needed in the world for improving surveillance capacities and real-time response against emerging diseases.

Some Innovative Approaches for Public Health and Epidemiology Informatics.

OBJECTIVES: Summarize excellent current research published in 2015 in the field of Public Health and Epidemiology Informatics. METHODS: The complete 2015 literature concerning public health and epidemiology informatics has been searched in PubMed and Web of Science, and the returned references were reviewed by the two section editors to select 14 candidate best papers. These papers were then peer-reviewed by external reviewers to allow the editorial team an enlightened selection of the best papers. RESULTS: Among the 1,272 references retrieved from PubMed and Web of Science, three were finally selected as best papers. The first one presents a language agnostic approach for epidemic event detection in news articles. The second paper describes a system using big health data gathered by a statewide system to forecast emergency department visits. The last paper proposes a rather original approach that uses machine learning to solve the old issue of outbreak detection and prediction. CONCLUSIONS: The increasing availability of data, now directly from health systems, will probably lead to a boom in public health surveillance systems and in large-scale epidemiologic studies.

The geographical spread of influenza.

How infectious diseases spread in space within one cycle of an epidemic is an important question that has received considerable theoretical attention. There are, however, few empirical studies to support theoretical approaches, because data are scarce. Weekly reports obtained since 1984 from a network of general practitioners spanning the entire French territory allows the analysis of the spatio-temporal dynamics of influenza over a fine spatial scale. This analysis indicates that diffusion over long distances, possibly due to global transportation systems, is so quick that homogeneous global mixing occurs before the epidemic builds up within infected patches. A simple model in which the total number of cases is given by the empirical time-series and cases are randomly assigned to patches according to the population weight of the patches exhibits the same spatio-temporal properties as real epidemic cycles: homogeneous mixing models constitute appropriate descriptions, except in the vicinity of the epidemic's peak, where geographic heterogeneities play a role.

Epidemic spread and bifurcation effects in two-dimensional network models with viral dynamics.

We extend a previous network model of viral dynamics to include host populations distributed in two space dimensions. The basic dynamical equations for the individual viral and immune effector densities within a host are bilinear with a natural threshold condition. In the general model, transmission between individuals is governed by three factors: a saturating function g( small middle dot) describing emission as a function of originating host virion level; a four-dimensional array B that determines transmission from each individual to every other individual; and a nonlinear function F, which describes the absorption of virions by a host for a given net arrival rate. A summary of the properties of the viral-effector dynamical system in a single host is given. In the numerical network studies, individuals are placed at the mesh points of a uniform rectangular grid and are connected with an m(2)xn(2) four-dimensional array with terms that decay exponentially with distance between hosts; g is linear and F has a simple step threshold. In a population of N=mn individuals, N0 are chosen randomly to be initially infected with the virus. We examine the dependence of maximal population viral load on the population dynamical parameters and find threshold effects that can be related to a transcritical bifurcation in the system of equations for individual virus and host effector populations. The effects of varying demographic parameters are also examined. Changes in alpha, which is related to mobility, and contact rate beta also show threshold effects. We also vary the density of (randomly chosen) initially infected individuals. The distribution of final size of the epidemic depends strongly on N0 but is invariably bimodal with mass concentrated mainly near either or both ends of the interval [1,N]. Thus large outbreaks may occur, with small probability, even with only very few initially infected hosts. The effects of immunization of various fractions of the population on the final size of the epidemic are also explored. The distribution of the final percentage infected is estimated by simulation. The mean of this quantity is obtained as a function of immunization rate and shows an almost linear decline for immunization rates up to about 0.2. When the immunization rate is increased past 0.2, the extra benefit accrues more slowly. We include a discussion of some approximations that illuminate threshold effects in demographic parameters and indicate how a mean-field approximation and more detailed studies of various geometries and rates of immunization could be a useful direction for future analysis.

Big data and smart health strategies: findings from the health information systems perspective.

OBJECTIVES: To summarize excellent current research in the field of Health Information Systems. METHOD: Creation of a synopsis of the articles selected for the 2014 edition of the IMIA Yearbook. RESULTS: Four papers from international peer reviewed journals were selected and are summarized. CONCLUSIONS: Selected articles illustrate current research regarding the impact and the evaluation of health information technology and the latest developments in health information exchange.

Health Information Systems. Toward Evidence-based Health Information Systems?

OBJECTIVES: Summarize excellent current research in the field of Health Information Systems. METHOD: Synopsis of the articles selected for the IMIA Yearbook 2013. RESULTS: Five papers from international peer reviewed journals have been selected for the section on health information systems. CONCLUSIONS: The selected articles illustrate current research regarding health information technology (IT) impacts and evaluation and the latest developments in health information exchange.

A space-time criterion for early detection of epidemics of influenza-like-illness.

OBJECTIVES: To develop a method based on a space-time criterion for early detection of epidemics of influenza-like-illness in France. METHODS: Since 1984, the French Communicable Diseases computer Network (FCDN) routinely detects epidemics of influenza-like-illness when the national incidence rate is, for 2 consecutive weeks, above a threshold computed by a periodic regression model. It appears that some areas reported early increases in incidence several weeks before the national epidemic. An optimised space-time criterion allows an early detection of the epidemic periods. RESULTS: Applying this space-time criterion to the last 11 epidemics (from 1986), the sensitivity was 0.82 and the specificity was 0.99. CONCLUSION: This simple procedure can be used as an additional tool for early detection of an epidemic taking into account the distribution of new cases in space and time.

Enhancement of epidemic spread by noise and stochastic resonance in spatial network models with viral dynamics.

We extend a previous dynamical viral network model to include stochastic effects. The dynamical equations for the viral and immune effector densities within a host population of size n are bilinear, and the noise is white, additive, and Gaussian. The individuals are connected with an n x n transmission matrix, with terms which decay exponentially with distance. In a single individual, for the range of noise parameters considered, it is found that increasing the amplitude of the noise tends to decrease the maximum mean virion level, and slightly accelerate its attainment. Two different spatial dynamical models are employed to ascertain the effects of environmental stochasticity on viral spread. In the first model transmission is unrestricted and there is no threshold within individuals. This model has the advantage that it can be analyzed using a Fokker-Planck approach. The noise is found both to synchronize and uniformize the trajectories of the viral levels across the population of infected individuals, and thus to promote the epidemic spread of the virus. Quantitative measures of the speed of spread and overall amplitude of the epidemic are obtained as functions of the noise and virulence parameters. The mean amplitude increases steadily without threshold effects for a fixed value of the virulence as the noise amplitude sigma is increased, and there is no evidence of a stochastic resonance. However, the speed of transmission, both with respect to its mean and variance, undergoes rapid increases as sigma changes by relatively small amounts. In the second, more realistic, model, there is a threshold for infection and an upper limit to the transmission rate. There may be no spread of infection at all in the absence of noise. With increasing noise level and a low threshold, the mean maximum virion level grows quickly and shows a broad-based stochastic resonance effect. When the threshold within individuals is increased, the mean population virion level increases only slowly as sigma increases, until a critical value is reached at which the mean infection level suddenly increases. Similar results are obtained when the parameters of the model are also randomized across the population. We conclude with a discussion and a description of a diffusion approximation for a model in which stochasticity arises through random contacts rather than fluctuation in ambient virion levels.

SITIE: a health care workstation integration architecture for epidemiologists.

SITIE is a workstation devoted to epidemiological data selection, analysis, and representation. Epidemiological data are collected using the French Communicable Diseases computer Network and stored in an Oracle database. Disease selection and spatial and temporal representations can be done using a user friendly graphic interface. SITIE automatically generates SQL requests to the Oracle database, extracts the data, processes it according to the user's choice, and represents the data. SITIE is built upon the AVS graphic package and allows the creation of new applications using previously developed modules linked together to form a network. SITIE can be viewed as a tool box for epidemiological data representations. Three example applications are detailed in order to make clear the way a new application can be built using SITIE. The reusability of modules is exemplified by a compound application.

Regulation of plasma calcium and phosphate in calcitonin-infused rats.

The effects of long-term constant infusion of moderate doses (2-32 ng/h) of salmon calcitonin (sCT) on plasma Ca (and its radionuclide 45Ca), Pi, Mg, and on endogenous rat CT (rCT) metabolism were investigated in the rat. Daily variations were included. 1) The plasma concentrations of Ca and Pi fell and that of Mg increased transiently during infusion, with the duration of responses (1-3 days) depending on the sCT dose. Rats infused with 8 ng/h sCT remained sensitive to CT after 7 and 14 days, as indicated by the effects of minipump removal and of a bolus injection of exogenous sCT on plasma mineral concentrations. 2) In contrast to control rats, the well-established daily variations in plasma Ca and Pi levels were no longer observed after 7 and 14 days of sCT infusion (8 ng/h), but normal variations persisted for plasma Mg, circulating rCT, rCT mRNA, and rCT thyroid content. 3) Statistical analysis of plasma mineral data, collected at five sequential times during days 7 and 14, showed that the means were not significantly different and that the daily variations were essentially identical on days 7 and 14 in control rats. In contrast, the variability of measurements for plasma Ca and Pi, but not for Mg, increased significantly between days 7 and 14 in infused rats, and the mean differences were significantly lower in infused rats on day 7 than in control rats. These results are consistent with a transitory loss of the daily variations for Ca and Pi (day 7) and the later (day 14) spontaneous recovery of some variations in these parameters, although the individuals remain unsynchronized.(ABSTRACT TRUNCATED AT 250 WORDS)