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[Application of geographical information systems in epidemiological studies exemplified by the ISAAC study in Munich].

Geographical Information Systems (GIS) are increasingly applied as modern tools for analysis and visualization of health-related spatial data, especially in epidemiological research. GIS are used by medical researchers and executives in the public health service. A community-based survey was conducted according to the phase II protocol of the International Study of Asthma and Allergies in Childhood (ISAAC) in Munich. The spatial patterns of disease incidence were analysed and related to exposure data by GIS. The prevalence study on fourth-grade pupils (n = 3354) and school beginners (n = 2890) was conducted during the school term 1995/96 in Munich. Parental questionnaires and measurements of lung function and immunological parameters were used. The questionnaire data were integrated in a GIS database. In this paper we discuss methodological aspects of GIS-based spatial analysis related to epidemiological data. In addition, we investigate whether there were spatial clusters of children with wheeze in the last 12 months of a magnitude unlikely to occur by chance and which could indicate local health risks. The study was based on permutation tests where global and local methods were applied. No spatial clusters of children with asthma symptoms were identified in the city of Munich.

Asthma↗

Geographical information systems as a tool in epidemiological assessment and wildlife disease management.

Geographical information systems (GIS) facilitate the incorporation of spatial relationships into epidemiological investigations of wildlife diseases. Consisting of data input, management, analysis and presentation components, GIS act as an integrative technology in that a range of very varied data sources can be combined which describe different aspect of the environment of wild animals. The analytical functionality of GIS is still evolving, and ranges from visual to exploratory and modelling methods. Output generated by GIS in map format has the particular advantage of allowing implicit representation of spatial dependence relationships in an intuitive manner. The technology is becoming an essential component of modern disease surveillance systems.

Animal Diseases↗

Geographic information systems and the environmental risk of schistosomiasis in Bahia, Brazil.

A geographic information system was constructed using maps of regional environmental features, Schistosoma mansoni prevalence in 30 representative municipalities, and snail distribution in Bahia, Brazil to study the spatial and temporal dynamics of infection and to identify environmental factors that influence the distribution of schistosomiasis. Results indicate that population density and the duration of annual dry period are the most important determinants of prevalence of schistosomiasis in the areas selected for study. Maximum rainfall, total precipitation during three consecutive months, annual maximum or minimum temperatures, and diurnal temperature difference were not shown to be significant factors influencing S. mansoni prevalence in local populations or distribution of snail hosts. Prevalence of the disease was highest in the coastal areas of the state. Higher prevalence tended to occur in areas with latossolo soil type and transitional vegetation.

Animals↗

The application of geographic information systems and spatial analysis to assess dumped and subsequently scattered human remains.

This study utilizes geographic information systems (GIS) and spatial analysis (SA) technology to address the problems associated with prediction of location and effective recovery of dumped and scattered human remains in Louisiana. The goals are to determine if a selective bias exists in Louisiana as to where and when human remains are dumped and to assess whether or not geographically specific patterns exist in the dispersal of human remains. We hypothesized that a positive relationship exists between postmortem interval (PMI) and dispersal distance, and that there are negative relationships between PMI and dispersal direction and between dispersal direction and distance. Our results indicate that, in Louisiana, remains are more often dumped in rural areas away from a structure, and are found within (1/4) mile of the nearest road. For Louisiana, no seasonal bias was found in the analysis of when remains are dumped. Furthermore, with the exception of the relationship between PMI and the shortest distance remains were dispersed, no geographically specific patterns were detected in the analyses of dispersal distance, dispersal direction, and PMI.

Environment↗

The need for open geographical information systems in medicine.

This paper presents a promising approach of using component-oriented geographical information systems (GIS) to facilitate improved medical and ecological applications. The integration of administrative geographical and medical data (map overlay) allows sophisticated and advanced analysis. This can serve as a basis to detect undiscovered relationships. We hope to increase the usage of geographical information by the creation of a general framework. This approach is mainly supported by two advances in recent years. Geographical data (e.g. administrative areas) is up-to-date, consistent and covers Germany completely. In addition, enormous technological improvements in the area of high-bandwidth networks and component-based software development have been made. These advances allowed to define our general framework for the integration of GIS functions into existing and already accepted applications.

Germany↗

A review of geographic information system and remote sensing with applications to the epidemiology and control of schistosomiasis in China.

Geographic information system (GIS) and remote sensing (RS) technologies offer new opportunities for rapid assessment of endemic areas, provision of reliable estimates of populations at risk, prediction of disease distributions in areas that lack baseline data and are difficult to access, and guidance of intervention strategies, so that scarce resources can be allocated in a cost-effective manner. Here, we focus on the epidemiology and control of schistosomiasis in China and review GIS and RS applications to date. These include mapping prevalence and intensity data of Schistosoma japonicum at a large scale, and identifying and predicting suitable habitats for Oncomelania hupensis, the intermediate host snail of S. japonicum, at a small scale. Other prominent applications have been the prediction of infection risk due to ecological transformations, particularly those induced by floods and water resource developments, and the potential impact of climate change. We also discuss the limitations of the previous work, and outline potential new applications of GIS and RS techniques, namely quantitative GIS, WebGIS, and utilization of emerging satellite information, as they hold promise to further enhance infection risk mapping and disease prediction. Finally, we stress current research needs to overcome some of the remaining challenges of GIS and RS applications for schistosomiasis, so that further and sustained progress can be made to control this disease in China and elsewhere.

Animals↗

[Geographic information systems as a tool for monitoring health inequalities].

OBJECTIVE: To show how geographic information systems (GISs) can be used as technological tools to support health policy and public health actions. METHODS: We assessed the relationship between infant mortality and a number of socio-economic and geographic determinants. In explaining how GISs are applied, we stressed their ability to integrate data, which makes it possible to perform epidemiologic evaluations in a simpler, faster, automated way that simultaneously analyzes multiple variables with different levels of aggregation. In this study, GISs were applied in analyzing infant mortality data with three levels of aggregation in countries of the Americas from 1995 to 2000. RESULTS: Infant mortality in the Region of the Americas was estimated at an overall average of 24.4 deaths per 1,000 live births. However, the inequalities that were found indicate that the probability of an infant death is almost 20 times greater in the less developed countries of the Region than in more developed ones. Mapping infant mortality throughout the Region of the Americas allowed us to identify the countries that need to focus more attention on health policy and health programs, but not to determine what specific actions are of the highest priority. An analysis of smaller geopolitical units (states and municipalities) revealed important differences within countries. This shows that, as is true of data for the entire Region of the Americas, using national-level average figures for indicators can obscure the differences that exist within countries. When we examined the relationship between female illiteracy and malnutrition as determinants of infant mortality in Brazil and Ecuador, we identified social and epidemiologic strata where risk factors had different distribution patterns and that thus require health interventions that match their individual social and epidemiologic profiles. CONCLUSIONS: With this type of epidemiologic study using GISs at the local level of health services, it is easy to see how a health event and its risk factors behave at a specific period in time. It is also possible to identify patterns in the spatial distribution of risk factors and in these factors' potential impact on health. Using GISs in an appropriate way will make it easier to deliver more effective, equitable public health services.

Americas↗

Surveillance around hazardous waste sites: geographic information systems and reproductive outcomes.

The purpose of this paper is to discuss the potential for integrating surveillance techniques in reproductive epidemiology with geographic information system technology in order to identify populations at risk around hazardous waste sites. Environmental epidemiologic studies have had problems with estimating or measuring exposures to individuals, and of detecting effects when the exposure is low, but continuous. In addition, exposures around hazardous waste sites are complex and frequently involve chemical mixtures. The birth weight of human babies has been reported to be sensitive to many environmental influences. Birth weight can be analyzed as a continuous variable or as a dichotomous one using the standard cutpoint of 2500 g or less to indicate low birth weight. It has the potential to be a powerful surveillance tool since exposures to the fetus reflect maternal and paternal exposures. The advent of recent environmental regulations pertaining to hazardous waste sites has greatly increased the availability of environmental data for many sites. The major problem with incorporating these data into epidemiologic studies has been with the logistics of data management and analysis. Computer-assisted geographic information systems hold promise in providing capabilities needed to address the data management and analysis requirements for effective epidemiologic studies around to hazardous waste sites.

Environmental Health↗

Spatial filtering using a raster geographic information system: methods for scaling health and environmental data.

Despite the use of geographic information systems (GIS) in academic research, it is still uncommon for public health officials to use such tools for addressing health and environmental issues. Complexities in methodological issues for addressing relationships between health and environment, investigating spatial variation of disease, and addressing spatial demand and supply of health care service, hinder the use of GIS in the health sector. This paper demonstrates simple spatial filtering methods for analyzing health and environmental data using a raster GIS. Computing spatial moving average rates reduces individual affects and creates a continuous surface of phenomena. Another spatial analytical method discussed is computation of exposure status surfaces including neighbors' influences weighted by distance decay. These methods describe how health and environmental data can be scaled in order to better address health problems. Spatial filtering methods are demonstrated using health and population surveillance data within a GIS that were collected for approximately 210,000 people in Matlab, Bangladesh.

Bangladesh↗

The use of a geographical information system for hospital catchment area research in Natal/KwaZulu.

We use a computerised geographical information system (GIS) to study the population per bed ratios and the implications of open access to the private and the formerly white hospital services in Natal. The advantages of the GIS method over the more usual administrative boundary-based beds per capita ratios are discussed. While the latter method would suggest that hospital bed resources in the province are racially unequal but nevertheless adequate (264 people per general and referral bed for the whole population, 195 for whites and 275 for blacks) the GIS analysis reveals widespread inadequacy, worse for blacks. Of the estimated hospital catchment areas half have more than 275 black people per general and referral bed, and half of these have more than 550 black people per bed. One-third of the catchment areas estimated for whites have ratios above 275 people per bed, and one half of these are also above 550 people per bed. The GIS analysis shows that open access to beds previously reserved for whites will make no difference to rural blacks, and almost none to urban blacks, because there were relatively few such beds, and they were concentrated in the cities. For the same reasons, the opening of private hospital beds to all patients would not significantly alleviate the apparent bed shortages in priority areas. By contrast, people in these priority areas would gain significantly improved access to general hospital care if selected chronic disease and industrial hospitals were upgraded to provide general hospital services.(ABSTRACT TRUNCATED AT 250 WORDS)

Catchment Area, Health↗

Factors influencing malaria endemicity in Yunnan Province, PR China (analysis of spatial pattern by GIS). Geographical Information System.

This study is an initial attempt to apply disease mapping through Geographical Information System (GIS) with multiple regression analysis to determine the nature and extent of factors influencing malaria transmission in Yunnan Province, PR China, particularly in border areas. Secondary county-based data covering the period 1990 to 1996 were collected and analyzed. The malaria situation in Yunnan Province as a whole is influenced mainly by the combined effects of the physical environment, the presence of efficient vector species, and mobile population along international borders with Myanmar, Lao PDR and Vietnam.

China↗

[Analysis for spatial distribution of Oncomelania snail in mainland China by geographic information system(GIS) database].

OBJECTIVE: To analyze spatial distribution of Oncomelania snail populations in mainland China by geographic information system (GIS) database. METHODS: Genetic variation experiment data and experimental data of susceptibility of 34 snail populations were collected from nine provinces in China, to set up a database. A world digital map was linked with the database in a software ArcView Release 3.0 a to be used to divide zones with ArcView spatial analyze function and GIS overlaying function. AVHRR NDVI satellite images were collected to form a new one for prevalent season, which were overlaid with distribution maps of heterozygous indices of snail populations, polymorphic locus percentage and infection rates of snail population with schistosome for classifying the images. RESULTS: Spatial analysis showed that distribution maps of genetic heterozygous indices of snail, percentage of polymophic loci and infection rate of snail can be divided into two large zones, i.e., east zone and west zone, both with varied pictures. Analysis for overlaying three-stratum distribution map with AVHRR NDVI satellite image showed four distinctly different spatial zones, including west Sichuan zone, west Yunnan zone, middle zone of river, lake and marshland, and southeast coastal zone. CONCLUSION: It is the first time using GIS to analyze data of Oncomelania population genetics and confirmed the population structure of Oncomelania snails presented discrete sub-population model, which supports the theory of sub-species of Oncomelania spp. Exited in mainland China.

Animals↗

[Development of a geographical information system and its application to Escherichia coli O-157 patient distribution].

The so called Geographical Information System (GIS) is one of the basic tools for wide range of public health applications. We had developed a general purpose GIS and applied it to represent geographical distribution of patients of the bacterium E. coli O-157 which bursted out in Japan last early summer particularly at Sakai City in Osaka Prefecture. The patient record have been supplied from the Food Safety Office of the Ministry of Health and Welfare. These records were handled by EXCEL. The basic geographical data was constructed from the map data provided by Japan Geographical Survey Institute, and ArcView 2 was used as the map system. The maps were converted to Graphics Interchange Format (GIF) files and put on our Web server.

Computer Communication Networks↗

Geographical Information System (GIS) as a tool for monitoring and analysing pesticide pollution and its impact on public health.

Geographical Information System (GIS) combines information from cartography sources (i.e. maps), earthbound surveys, remote sensing (i.e. aerial and satellite imagery) and creates overlapping layers that can be accessed, transformed, and manipulated interactively in one spatial structure. Thanks to the great flexibility of GIS, its possible applications are countless. For example, dynamic databases created by GIS can manage information from various sources and make spatial correlations with epidemiological data about temporal distribution of environmentally-related diseases. GIS has also been increasingly used to monitor, analyse and model pesticide migration in the environment. GIS analysis has proved to be a valuable tool in environmental and public health studies yielding important results that may ultimately help prevent excessive or uncontrolled exposure to xenobiotics, including pesticides. Despite its obvious advantages GIS technology is still not commonly used for such studies, particularly in the developing countries where the knowledge about GIS technology and its accessibility is limited. The presented review briefly explains the basic features of GIS and discusses exemplary studies where this technology has been successfully used for monitoring and analysing pesticide pollution and its impact on public health.

Databases, Factual↗

[Study on the geographic information system databases regarding the control of schistosomiasis in Zhongxiang, Hubei province, China].

OBJECTIVE: Using geographic information system (GIS) and the remote sensing techniques (RS), we developed a schistosomiasis database and geographic distribution map in Zhongxiang city,Hubei province in order to display and analyze the endemic situation longitudinally after the water conservancy project is completed. METHODS: Epidemiological data of schistosomiasis and the correlated climate and hydrology data for the last 30 years were collected and the relevant GIS databases were established under Artificial Neural Networks(ANN) and network training of Landsat TM images. RESULTS: GIS database of schistosomiasis in Zhongxiang city, Hubei province and its vicinity areas were developed including 1 maps regarding the epidemic situation of schistosomiasis. The areas of snail distributing were 4.4 hm2, 8.2 hm2, 24 hm2, 130.4 hm2, 8.13 hm2 and 7.53 hm2, respectively. CONCLUSION: The maps created by GIS database and RS techniques supported the complicated query on space and property, providing a new way in keeping,updating and analyzing available data. The techniques used should be able to provide evidence for the control of schistosomiasis to this water conservancy project.

Animals↗

[An attempt to estimate geographical accessibility to day service facilities among the elderly with a geographical information system].

OBJECTIVE: The objective of this study was to assess inequality in geographical accessibility to day service among the elderly in a municipality using a geographical information system (GIS). We also examined problems in measuring geographical accessibility and ways to validate results. METHODS: The target was Hachioji City. The following two data sets were constructed: a data set for day service facilities for all of Hachioji City and a data set for the people aged 65 and over, living within 1 km meshes in Hachioji City. These were integrated and displayed on a digital map with GIS software. Geographical accessibility was estimated by measuring the shortest road distance from the center point of each mesh to day service facilities. RESULTS: There were 47 day service facilities serving Hachioji City in October, 2000 and 139 meshes that had elderly residents. Their center points were all located within Hachioji City, which was estimated to have 73,760 elderly in 2000. The mean distance from the center point of each mesh to the nearest day service facility was 1.99 km (SD = 1.75, max = 9.21, min = 0.03). The proportions of the elderly who had 5 or more facilities within 3 km and 5 km from their residence were estimated to be 57.3% and 96.4%, respectively. CONCLUSIONS: The results of this study suggest that there is variation in geographical accessibility to day service facilities among the elderly living in a relatively large municipality. It is now necessary to examine whether the difference in geographical accessibility to day service affects the service utilization.

Aged↗

The potential of geographical information systems and remote sensing in the epidemiology and control of human helminth infections.

Geographic information systems (GIS) and remote sensing (RS) technologies are being used increasingly to study the spatial and temporal patterns of infectious diseases. For helminth infections, however, such applications have only recently begun despite the recognition that infection distribution patterns in endemic areas may have profound effects on parasite population dynamics and therefore the design and implementation of successful control programmes. Here, we review the early applications of these technologies to the major human helminths (geohelminths, schistosomes and the major lymphatic filarial worms), which demonstrate the potential of these tools to serve as: (1) an effective data capture, mapping and analysis tool for the development of helminth atlases; (2) an environment for modeling the spatial distribution of infection in relation to RS and environmental variables, hence furthering the understanding of the impact of density-independent factors in underlying observed parasite spatial distributions and their effective prediction; and (3) a focal tool in parasite control programming given their abilities to (i) better define endemic areas, (ii) provide more precise estimates of populations-at-risk, (iii) map their distribution in relation to health facilities and (iv) by facilitating the stratification of areas by infection risk probabilities, to aid in the design of optimal drug or health measure delivery systems. These applications suggest a successful role for GIS/RS applications in investigating the spatial epidemiology of the major human helminths. It is evident that further work addressing a range of critical issues include problems of data quality, the need for a better understanding of the population biological impact of environmental factors on critical stages of the parasite life-cycle, the impacts and consequences of spatial scale on these relationships, and the development and use of appropriate spatially-explicit statistical and modeling techniques in data analysis, is required if the true potential of this tool to helminthology is to be fully realized.

Animals↗

Estimating the cost of an interview survey using geographic information system software.

Estimating the cost of interview surveys is difficult but important. A geographic information system (GIS) was used to determine the shortest time route to survey 533 medical facility locations in Perth. The results provided time and cost estimates for undertaking the survey and the interviewer agreed to a contract for the job on the basis of these estimates.

Costs and Cost Analysis↗