The use of high-resolution remote sensing for plague surveillance in Kazakhstan E.A. Addink a, ⁎, S.M. De Jong a , S.A. Davis b,c , V. Dubyanskiy d , L.A. Burdelov d , H. Leirs e,f a Utrecht University, Department of Physical Geography, Heidelberglaan 2, PO Box 80115, 3508 TC Utrecht, The Netherlands b Yale University, School of Medicine, Epidemiology and Public Health, 60 College Street, PO Box 208034, New Haven, Connecticut 06520-8034, USA c Utrecht University, Department of Veterinary Medicine, Yalelaan 1, PO Box 80163, 3508 TD Utrecht, The Netherlands d Anti Plague Institute, M. Aikimbayev's Kazakh Science Center for Quarantine and Zoonotic Diseases, 14 Kapalskaya Street, Almaty 050074, Kazakhstan e University of Antwerp, Department of Biology, Groenenborgerlaan 171, B-2020 Antwerpen, Belgium f Danish Pest Infestation Laboratory, University of Aarhus, Department of Integrated Pest Management, Skovbrynet 14, DK-2800 Kongens Lyngby, Denmark abstract article info Article history: Received 24 March 2009 Received in revised form 11 November 2009 Accepted 16 November 2009 Keywords: Bubonic plague Object-based image analysis Quickbird Bubonic plague, caused by the bacteria Yersinia pestis, persists as a public health problem in many parts of the world, including central Kazakhstan. Bubonic plague occurs most often in humans through a flea bite, when a questing flea fails to find a rodent host. For many of the plague foci in Kazakhstan the great gerbil is the major host of plague, a social rodent well-adapted to desert environments. Intensive monitoring and prevention of plague in gerbils started in 1947, reducing the number of human cases and mortalities drastically. However, the monitoring is labour-intensive and hence expensive and is now under threat due to financial constraints. Previous research showed that the occupancy rate of the burrow systems of the great gerbil is a strong indicator for the probability of a plague outbreak. The burrow systems are around 30 m in diameter with a bare surface. This paper aims to demonstrate the automatic classification of burrow systems in satellite images using object-oriented analysis. We performed field campaigns in September 2007 and May and September 2008 and acquired corresponding QuickBird images of the first two periods. User's and producer's accuracy values of the classification reached 60 and 86%, respectively, providing proof of concept that automatic mapping of burrow systems using high-resolution satellite images is possible. Such maps, by better defining great gerbil foci, locating new or expanding foci and measuring the density of great gerbil burrow systems could play a major role in a renewed monitoring system by better directing surveillance and control efforts. Furthermore, if similar analyses can separate occupied burrow systems from empty ones, then very-high-resolution images stand to play a crucial role in plague surveillance throughout central Asia. © 2009 Elsevier Inc. All rights reserved. 1. Introduction Bubonic plague is best known for the disastrous effects that it had in the mid 14th century. This outbreak of bubonic plague, more commonly referred to as the Black Death, was one of the deadliest pandemics in human history. Death toll estimates greatly vary but it is believed that in southern Europe around 75% of the population fell victim and in central Europe around 50% of the population died from this disease. Although plague is now absent from Europe and can be treated with antibiotics, it persists on all other continents except for Australia. In North America, human cases occur but plague is mainly a conservation concern as it plays havoc with efforts such as re-introductions of the black-footed ferret. Most human cases reported to the World Health Organization (WHO) now come from Africa, and in places like Madagascar, Tanzania and the DR Congo it is a serious public health issue with frequent human cases and deaths (Davis et al., 2004; Laudisoit et al., 2007). In central Asia too, plague remains a public health concern. Plague is a vector-borne disease, i.e. the disease is spread by arthropod vectors that live and feed on hosts (Gage and Kosoy, 2005). In the steppe areas of Kazakhstan the hosts are great gerbils Rhomb- omys opimus. Transmission happens through bites of infected fleas that earlier fed on infected hosts. In the late 1940s, the Soviet government began an intensive monitoring and control programme to prevent outbreaks of human plague in Central Asia. Within this monitoring system samples (of fleas and rodents) were collected from 10 by 10 km areas (“sectors”) and tested for plague by the Anti Plague Institute of Kazakhstan. The PreBalkhash focus (one of at least 18 plague foci in Kazakhstan) alone has over 350 such sectors spread out over an area of thousands square kilometers. The monitoring programme is very labor intensive and expensive and in this study we investigate how high-resolution earth observation may contribute to the monitoring programme and in controlling the outbreaks of bubonic plague. The monitoring programme would greatly benefit from information about the whereabouts of the great gerbils (their burrows), the degree of occupancy of the burrows and the dynamics of the great gerbil population over the seasons and the years. Remote Sensing of Environment 114 (2010) 674–681 ⁎ Corresponding author. E-mail address: e.addink@geo.uu.nl (E.A. Addink). 0034-4257/$ – see front matter © 2009 Elsevier Inc. All rights reserved. doi:10.1016/j.rse.2009.11.015 Contents lists available at ScienceDirect Remote Sensing of Environment journal homepage: www.elsevier.com/locate/rse