Need for improved methods to collect and present spatial epidemiologic data for vectorborne diseases

Abstract

Improved methods for collection and presentation of spatial epidemiologic data are needed for vectorborne diseases in the United States. Lack of reliable data for probable pathogen exposure site has emerged as a major obstacle to the development of predictive spatial risk models. Although plague case investigations can serve as a model for how to ideally generate needed information, this comprehensive approach is cost-prohibitive for more common and less severe diseases. New methods are urgently needed to determine probable pathogen exposure sites that will yield reliable results while taking into account economic and time constraints of the public health system and attending physicians. Recent data demonstrate the need for a change from use of the county spatial unit for presentation of incidence of vectorborne diseases to more precise ZIP code or census tract scales. Such fine-scale spatial risk patterns can be communicated to the public and medical community through Web-mapping approaches.

Figure 1

Areas predicted by a model based on peridomestically acquired plague cases from 1957 through 2004 to pose high risk to humans in the Four Corners Region (Arizona, Colorado, New Mexico, and Utah) are depicted in light gray. Those high-risk areas on privately or tribally owned land are shown in dark gray. Black circles represent locations of peridomestically acquired human plague cases. States comprising the Four Corners Region are shown within the United States in the inset. Reprinted with permission of the Journal of Medical Entomology from Eisen et al. (9).

Figure 2

Comparison of spatial distributions of areas of California with different incidences of endemic Lyme disease (LD), 1993–2005, when calculated by A) the county spatial unit and B) the 5-digit ZIP code spatial unit. Adapted from a figure published in the American Journal of Tropical Medicine and Hygiene by Eisen et al. (8).

Figure 3

State and county boundaries within the contiguous United States. Note the increasing size of counties from east to west.