Space technologies for the delineation of potential habitats of Banticota indica rodents, Hantavirus hosts in Nakhon Pathom province (Thailand)  Mr. Vincent Herbreteau Center for Vectors and Vector-borne Diseases Faculty of Sciences and Technology, Mahidol University Thanon Rama VI, Phyathai, Ratchatevi, Bangkok 10400, Thailand Email : vherbreteau@hotmail.com Tel : (66) 2 201 5934 (office), (66) 2 201 5931 (center) Fax : (66) 2 247 0079 H. Andrianasolo Asian Institute of Technology, Thailand - IRD (Institute pour la Recherche et le Développement), UR034, Thailand. G. Chauvancy IRD (Institute pour la Recherche et le Développement), UR034, Thailand. J.P. Gonzalez IRD (Institute pour la Recherche et le Développement), UR034, Thailand. Abstract The emerging diseases are mostly caused by viruses and among them hantaviruses regroup some viral species, which have been documented for only a few years. Rodents are vectors and reservoirs of hantaviruses and many other zoonotic diseases. In the frame of a research on emerging diseases, we have then decided to focus this work on a vector approach. The aim of this study was to realize the delineation of the habitats of Bandicota indica, the main rodent with medical interest in Thailand. It allows assessing the potential contacts for humans with this rodent and then the risks of human exposure to the related diseases. We used space technologies to delimit each rodent habitat by identifying the ecological parameters, which describe the ecology of Bandicota indica. The study was realized in Nakhon Pathom province (west of Bangkok, Thailand) where a large sampling has been conducted. From the rodents trapped and the data associated we can define the parameters (physical, demographic, social), which characterize the species and then make its distribution. This delineation helps now to improve the sampling and adapt the model for other Thai study areas. Furthermore it helps to go on our research on the dynamics of rodents and emerging rodent-borne diseases. 1. Introduction The historical association of wild animals, especially rodents, with certain human endemic diseases is well documented and was referred to for centuries before the economic and scientific developments since the nineteenth century. However knowledge concerning the enzootic nature of such diseases in relation to the ecology of rodent vectors and even more the understanding of the environmental changes that make a disease emerge has rarely been studied. Rodents are known to carry many diseases and in particular hantaviruses, which have caused several deaths especially in North America. Deaths caused by hantaviruses have recently been registered in Thailand. The emergence of hantavirus related diseases is now reaching Thailand, where these diseases are still not studied. Little data is then available but this creates a great challenge to describe the present state of hantaviruses. This study deals with the identification and delineation of the main rodent with medical interest in Thailand in order to assess the human exposure to hantavirus related diseases. It is part of a study on emerging viral diseases realized in cooperation with the Asian Institute of Technology and the unit 34 of IRD (Institut de Recherche pour le Développement) in Salaya (Thailand). 2. Material We have chosen Nakhon Pathom province as study area, because of its suitable location in the west of Bangkok metropolitan area (56 km) and the large database already collected there. It’s a small Thai province (2168,327 sq. km), composed of 7 districts and 104 tambons (sub-districts). Rodents have been studied for several years by the unit 34 of IRD in Salaya. The data is huge and tackles ecological, medical and human aspects. This database constitutes a first step in the description of vectors. For each rodent caught, a characterization of the ecology has been made in order to describe the different habitats. The GPS coordinates have also been taken to localize precisely each sample and allow us to integrate this data in a GIS. Among the rodents trapped in Nakhon Pathom province, Bandicota indica (Bandioot rat) was the most frequently caught. This species is also known to be vector of the THAI hantavirus. Then we kept it as the studied rodent for this delineation. We used space technologies to describe the whole province from satellite images. They provide a synoptic view, which allows delineating the land use classes and also their spatial distribution. We processed a LANDSAT 5 TM image acquired on 11th June 1997. The resolution of thus image, which is 30 meters for one pixel, is quite low but convenient relating to the large study area.
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