West Nile Virus Infection Risk is Associated with Combined Sewer Overflow Streams in Urban Atlanta, Georgia

Environmental Health Perspectives, 2010

Gonzalo M. Vazquez-Prokopec, Jodi L. Vanden Eng, Rosmarie Kelly, Daniel G. Mead, Priti Kolhe, James Howgate, Uriel Kitron, and Thomas R. Burkot

“Background. At present, the factors favoring transmission and amplification of West Nile Virus (WNV) within urban environments are poorly understood. In urban Atlanta, GA, the highly polluted waters of Combined Sewer Overflow (CSO) affected streams represent significant habitats for the WNV mosquito vector Culex quinquefasciatus. However, their contribution to the risk of WNV infection in humans and birds remains unclear.

“Objectives. Our goals were to describe and quantify the spatial distribution of WNV infection in mosquitoes, humans and corvids (blue jays and American crows, which are particularly susceptible to WNV infection) and to assess the relationship between WNV infection and proximity to CSO-affected streams in the city of Atlanta, Georgia.

“Materials and Methods. We applied spatial statistics to human, corvid and mosquito WNV surveillance data from 2001-2007. Multi-model analysis was used to estimate associations of WNV infection in Cx. quinquefasciatus, humans and dead corvids with selected risk factors including distance to CSO-streams and catch basins, land cover, median household income, and housing characteristics.

“Results. WNV infection in mosquitoes, corvids and humans was spatially clustered and statistically associated with CSO-affected streams. WNV infection in Cx. quinquefasciatus was significantly higher in CSO compared with non-CSO streams, and WNV infection rates in humans and corvids were significantly associated with proximity to CSO-affected streams, the extent of tree cover and median household income.

“Conclusions. Our study strongly suggests that CSO-affected streams are significant sources of Cx. quinquefasciatus mosquitoes that may facilitate WNV transmission to humans within urban environments. Our findings may have direct implications for the surveillance and control of WNV in other urban centers that continue to use CSOs as a waste management practice.”

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