, Martin Kulldorff†, Jessica J. Hartman*, James R. Miller*, and Varuni Kulasekera†
Figure 3. Dead bird clusters, West Nile virus (WNV)-positive dead birds, human cases, and mosquito traps, New York City, 2001. The shading represents the cumulative frequency of dead bird clusters in each census tract as of the date of analysis. Cumulative WNV-positive birds and mosquitoes are displayed on the basis of their date of collection; human cases are shown on the basis of their date of onset of illness.