Spatial patterns of tuberculosis incidence in Cologne (Germany).

In many European countries, the decline of tuberculosis notification rates levelled off in the mid 1980s. Germany has been facing only a very modest resurgence of tuberculosis (TB) in the early 1990s, but until now, the notification rate does not yet fulfil the WHO definition of a low incidence country. Mainly immigration from high incidence countries is held responsible for the delayed decline and temporary increase of TB. This paper seeks to investigate the inner-urban strength of association between tuberculosis and several potential risk factors in the city of Cologne using geographical and statistical methods within a small-area division based, GIS-supported ecological study, which never before has been conducted for a German city. Standardised annual TB incidence rates for 78 urban subdistricts between 1986 and 1997, disaggregated by age, have been analysed. Twelve independent variables representing contemporary ethnic and socioeconomic conditions are used to calculate Poisson regression models. For the entire population and for the <60 age group, a strong positive association was found between tuberculosis incidence and share of immigrants. Interestingly enough the share of German-origin immigrants from eastern Europe was seen not to be instrumental in increasing TB rates. Reflecting strong ecological correlations between variables depicting economic conditions and TB as well as immigration variables, the deprivation of certain ethnicities rather than high prevalence immigration background is inferred to be significant to TB level. As for the 60 + age group regression analysis fails to model the TB incidence patterns sufficiently it seems reasonable to assume an autonomous, spatially disaggregated TB epidemic of the elderly, echoing a severe post-war epidemic by reactivation, only marginally associated with contemporary living conditions, but contributing substantially to the current TB incidence level. This assumption is reinforced by further results of the statistical analysis (deviance of regression null models, testing for Normal distribution, time trends). It could be shown that in Cologne the HIV/AIDS epidemic is not significantly influencing the TB incidence rate of men aged 30-49 being the most AIDS-afflicted population subgroup.

New perspectives on the use of Geographical Information Systems (GIS) in environmental health sciences.

At first glance, the domain of health is no typical area to applicate Geographical Information Systems (GIS). Nevertheless, the recent development clearly shows that also within the domains of environmental health, disease ecology and public health GIS have become an indispensable tool for processing, analysing and visualising spatial data. In the field of geographical epidemiology, GIS are used for drawing up disease maps and for ecological analysis. The striking advantages of GIS for the disease mapping process are the considerably simplified generation and variation of maps as well as a broader variety in terms of determining a real units. In the frame of ecological analysis, GIS can significantly assist with the assessment of the distribution of health-relevant environmental factors via interpolation and modelling. On the other hand, the GIS-supported methods for the detection of striking spatial patterns of disease distribution need to be much improved. An important topic in this respect is the integration of the time dimension. The increasing use of remote sensing as well as the integration into internet functionalities will stimulate the application of GIS in the field of Environmental Health Sciences (EHS). In future, the integration and analysis of health-relevant data in one single data system will open up many new research opportunities.

Spatial patterns of diarrhoeal illnesses with regard to water supply structures--a GIS analysis.

This paper presents an application of a geographical information system (GIS) in the field of research of drinking water epidemiology. A retrospective study regarding gastrointestinal infections was carried out in the Rhine-Berg District (North Rhine-Westphalia, Germany), which is characterised by different drinking water supply structures. The main objective was to examine the hypothesis that spatial variations of diarrhoeal illnesses may be linked with different drinking water sources (groundwater or surface water). We introduced a GIS for storing and analysing the wide range of data sets comprising features of the water supply structure and the epidemiological databases which constitute the basic elements of a surveillance-system for waterborne infectious diseases. GIS-techniques supported the generation of hypotheses regarding disease distribution and causation. The data bases which are routinely available turned out to be of sufficient quantity and quality for running a waterborne disease surveillance-system. Geo-statistical analysis revealed spatial variations in the incidence of diarrhoeal illnesses. Parameters depicting the water supply structures, especially the amount of drinking water produced from surface or groundwater, were correlated with the age-standardised incidence rates of gastrointestinal infections. The correlation models showed a trend of positive linkage between disease incidence and amount of groundwater. We found GIS-techniques extremely useful to carry out area-based correlation studies and to analyse the exposure of populations in drinking water epidemiology.