The risk of West Nile Virus infection is associated with combined sewer overflow streams in urban Atlanta, Georgia, USA.
BACKGROUND
At present, the factors favoring transmission and amplification of West Nile Virus (WNV) within urban environments are poorly understood. In urban Atlanta, Georgia, the highly polluted waters of streams affected by combined sewer overflow (CSO) 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.


OBJECTIVE
Our goals were to describe and quantify the spatial distribution of WNV infection in mosquitoes, humans, and corvids, such as blue jays and American crows that 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.


METHODS
We applied spatial statistics to human, corvid, and mosquito WNV surveillance data from 2001 through 2007. Multimodel 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
We found that 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 among 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 CSO systems as a waste management practice.
Department of Environmental Studies, Emory University, Atlanta, Georgia 30322, USA. gmvazqu@emory.edu
Gonzalo M
GM
Vazquez-Prokopec
Jodi L
JL
Vanden Eng
Rosmarie
R
Kelly
Daniel G
DG
Mead
Priti
P
Kolhe
James
J
Howgate
Uriel
U
Kitron
Thomas R
TR
Burkot
D005845:Georgia / Q000453:epidemiology; D006801:Humans; D012722:Sewage; D014505:Urban Population; D014901:West Nile Fever / Q000453:epidemiology*
D012722:Sewage