In Memorium: Swamy Laxminarayan [1939–2005]

Background: West Nile virus infection in humans in urban areas of the Midwestern United States has exhibited strong spatial clustering during epidemic years. We derived urban landscape classes from the physical and socio-economic factors hypothesized to be associated with West Nile Virus (WNV) transmission and compared those to human cases of illness in 2002 in Chicago and Detroit. The objectives were to improve understanding of human exposure to virus-infected mosquitoes in the urban context, and to assess the degree to which environmental factors found to be important in Chicago were also found in Detroit. Results: Five urban classes that partitioned the urban space were developed for each city region. The classes had many similarities in the two settings. In both regions, the WNV case rate was considerably higher in the urban class associated with the Inner Suburbs, where 1940–1960 era housing dominates, vegetation cover is moderate, and population density is moderate. The land cover mapping approach played an important role in the successful and consistent classification of the urban areas. Conclusion: The analysis demonstrates how urban form and past land use decisions can influence transmission of a vector-borne virus. In addition, the results are helpful to develop hypotheses regarding urban landscape features and WNV transmission, they provide a structured method to stratify the urban areas to locate representative field study sites specifically for WNV, and this analysis contributes to the question of how the urban environment affects human health. Background By November, 2006, the West Nile virus (WNV) was associated with 23,593 cases of recorded illness in humans and 905 deaths since its introduction into the United States in 1999 [1]. The primary transmission of WNV to humans is through infected mosquitoes that have fed on infected birds [2]. Between 1999 and 2001, only several dozen human cases were reported each year; however, in 2002, the number of WNV cases in the U.S. increased markedly to 4,156. Illinois and Michigan led the nation in numbers of human cases of illness from WNV that year (884 and 644 cases respectively), with important focal Published: 12 March 2007 International Journal of Health Geographics 2007, 6:10 doi:10.1186/1476-072X-6-10 Received: 30 December 2006 Accepted: 12 March 2007 This article is available from: http://www.ij-healthgeographics.com/content/6/1/10 © 2007 Ruiz et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.