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Geospatial Health 6(2), 2012, pp. 195-203 A real-time platform for monitoring schistosomiasis transmission supported by Google Earth and a web-based geographical information system Kun Yang1,2, Le-Ping Sun1,2, Yi-Xin Huang1,2, Guo-Jing Yang1,2, Feng Wu1,2, De-Rong Hang1,2, Wei Li1,2, Jian-Feng Zhang1,2, Yong-Sheng Liang1,2, Xiao-Nong Zhou3,4 1Jiangsu Institute of Parasitic Diseases, Wuxi 214064, People’s Republic of China; 2Key Laboratory on Technology for Parasitic Disease Prevention and Control, Ministry of Health, Wuxi 214064, People’s Republic of China; 3National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, Shanghai 200025, People’s Republic of China; 4WHO Collaborating Center for Malaria, Schistosomiasis and Filariasis, Key Laboratory of Parasite and Vector Biology, Ministry of Health, Shanghai, 200025, People’s Republic of China Abstract. A basic framework for the rapid assessment of the risk for schistosomiasis was developed by combining spatial data from Google Earth® with a geographical information system (GIS) package, bundling the modules together with an Internet connection into a WebGIS platform. It operates through functions such as “search“, “evaluation“, “risk analysis“ and “prediction“ and is primarily aimed to be a dynamic, early-warning system (EWS) providing user-friendly, evidence- based, near real-time awareness of the status of an important endemic disease. It contributes to rapid information-sharing at all levels of decision-making, facilitating “point-of-care“ response, i.e. treatment provided at newly discovered transmis- sion sites. The experience using the platform is encouraging and it has the potential to improve support systems and strength- en schistosomiasis control activities, in particular with regard to surveillance and EWS. It can quickly and intuitively locate early, high-risk areas, retrieve all important data needed as well as provide detailed, up-to-date information on the per- formance of the control programme. This WebGIS, the first of its kind in the People’s Republic of China, is not only appli- cable for schistosomiasis but can easily be adapted for improving control of any endemic disease in any geographical area. Keywords: geographical information system, remote sensing, spatio-temporal epidemiology, Google Earth, real-time sur- veillance, early-warning system, schistosomiasis, People’s Republic of China. Introduction These tools have proved particularly useful for the study of infectious agents relying on intermediate Remotely sensed data on land cover, elevation, tem- hosts for the completion of their lifecycles, since both perature, rainfall, etc. complement geographical infor- are vulnerable to changes in temperature, humidity, mation systems (GIS) by providing access to continu- and vegetation cover. The improved possibilities to ously updated background information. The Internet study the boundaries of the intermediate hosts and has played an integral part in this development allow- vectors, on which parasites often depend, have pro- ing scientists, control officers and decision-makers moted the field for gaining epidemiological informa- shared access to near real-time data. The presentation tion from satellite imagery (Hendrickx et al., 2004; of data based on interactive, computer-generated map Cringoli et al., 2005; Rinaldi et al., 2006). In addition, applications represents a straightforward way of visu- remote sensing had a strong impact on the creation of alizing large numbers of datasets in a geographical virtual globes with far-reaching consequences for any context for the non-specialist. activities having to do with map-based information. The industry has not been slow in utilizing this novel way of collating and visualizing this information Corresponding author: (http://www.google.com/earth/index.html), nor have Xiao-Nong Zhou National Institute of Parasitic Diseases professional epidemiologists deferred using this novel Chinese Center Diseases Control and Prevention approach (Stensgaard et al., 2009). Shanghai 200025 Many endemic diseases can be expected to occupy People’s Republic of China Tel. +86 21 64738058; Fax +86 21 64332670 new areas when climatic conditions change. This sce- E-mail address: [email protected] nario looks increasingly likely, for example with 196 K. Yang et al. - Geospatial Health 6(2), 2012, pp. 195-203 respect to schistosomiasis in the People’s Republic of Internet for dissemination of the information (Kamel China (P.R. China) (Yang et al., 2006) and leishmani- Boulos, 2004; Ptochos et al., 2004; Kamadjeu and asis and dirofilariasis in Italy (Otranto et al., 2009). Tolentino, 2006; Zhou et al., 2009). In addition, Indeed, several vector-borne diseases have emerged Google Earth® provides free access to satellite imagery and spread due to global and/or local changes along with editing tools for the generation of data-lay- (Hendrickx et al., 2004; Rogers and Randolph, 2006). ers for terrain, boundaries and socioeconomic infra- The current increase in international trade, tourism structures (Conroy et al., 2008; Lefer et al., 2008; and travel are also important drivers for the prolifera- Lozano-Fuentes et al., 2008; Chang et al., 2009). The tion of vector-borne parasites into new geographical aim of this study is to describe the design and testing areas (Harrus and Baneth, 2005). of a real-time, web-based platform (WebGIS) for schis- The parasitic trematode worm Schistosoma japon- tosomiasis surveillance in P.R. China. icum, the cause of schistosomiasis in P.R. China, requires the presence of a snail intermediate host, Materials and methods Oncomelania hupensis, to complete its lifecycle. This snail is common in the streams, great lakes and along Study area the Yangtze River in the southern part of the country. Strong advances in the control of S. japonicum have The lower reaches of the Yangtze River in Jiangsu been made in P.R. China, but elimination of schistoso- province, covering 102,600 km2 along the eastern miasis has yet to be achieved (Zhou et al., 2005, coast of P.R. China with a population of about 72 mil- 2007). Chinese applications of remote sensing and GIS lion, was chosen as trial area for the proposed for the study of the epidemiology of Schistosomiasis approach to schistosomiasis control. Even if the situa- have shown potential for improving the spatio-tempo- tion has improved along with the progress of the schis- ral aspects of disease surveillance including the devel- tosomiasis control programme, this area still con- opment of risk-mapping and predictive distribution tained 72 km2 of snail habitats and 18 km2 of high- studies at scales ranging from micro to macro. risk areas in 2006 (Sun et al., 2008; Hong et al., Prediction maps have been generated by the Bayesian 2011). It can therefore be expected that thousands of Poisson spatial model together with environmental people still run the risk of becoming infected (or re- surrogates and landscape metrics to predict the spatial infected) with S. japonicum each year. distribution of O. hupensis locally (Yang et al., 2005a, 2008, 2009; Zhou et al. 2009, 2010). However, the Development of the database approach is far from straightforward and there are obstacles restricting full utilization of the new tech- Designed to encompass broad information on geo- nologies. Firstly, spatio-temporal epidemiology is a graphical risk, the database is divided into three com- sophisticated profession requiring training, expertise ponents: one for the prevalence of the parasite in its and experience. Secondly, the cost of the necessary, definite hosts (humans and bovines for now, but keep- specialized software such as ArcGIS ing the door open for the inclusion of other species in (http://www.esri.com/software/arcgis/index.html), the future), one for the snail intermediate host, its dis- MapInfo (http://www.pbinsight.se/) or ERDAS tribution, infection prevalence and presence of cercari- (http://www.erdas.com/Homepage.aspx) is compara- ae (the infective stage of the parasite) in the water, and tively high since the software comes in packages con- one for the transmission risk owing to the characteris- taining a multitude of functions, only a few of which tics of general environmental. Risk maps were created are required in epidemiological research. Thirdly, real- by merging information on schistosomiasis epidemiol- time monitoring (e.g. of risk factors) is a necessity for ogy and cercarial presence in water-bodies along with early warning systems (EWS), without which counter landscape features of epidemiological interest. This responses would have a much reduced effect. information depends on processing and storage of GIS applications, although sometimes costly, are original data in the three components of the database. acquired at an ever increasing pace, which is likely to The server side of the database is interactive in the result in an exponential increase of the number of sense that, in addition to downloading disease-related potential users (Kamel Boulos, 2004; Chang et al., information, the user may also upload data to be 2009). The impediments related to cost and distribu- shared with others. tion of findings can be overcome by the current avail- The database was fed with data from previous field ability of free software for mapping and the use of the surveys for schistosomiasis in humans and bovines as K. Yang et al. - Geospatial Health 6(2), 2012, pp. 195-203 197 well as data on snail densities in various places, includ- bodies, villages,

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