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The risk of West Nile Virus infection is associated with combined sewer overflow streams in urban Atlanta, Georgia, USA.

Vazquez-Prokopec GM, Vanden Eng JL, Kelly R, Mead DG, Kolhe P, Howgate J, Kitron U, Burkot TR - Environ. Health Perspect. (2010)

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Environmental Studies, Emory University, Atlanta, Georgia 30322, USA. gmvazqu@emory.edu

ABSTRACT

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.

Objectives: 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.

Materials and 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.

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(A) Abundance (mosquitoes/trap-night), density distribution (mosquitoes/ha), and local spatial clustering of Cx. quinquefasciatus abundance, 2001–2007. (B) Distribution of WNV infections in Cx. quinquefasciatus and location of clusters of high ML WNV infection intensity [Gi*(d)] and presence (Bernoulli test) in mosquito pools (Cx. quinquefasciatus grouped according to date and location) tested during 2001–2007. Large insets show a detailed view of the city of Atlanta, whereas the upper right inset shows the location of Fulton County.
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f1-ehp-118-1382: (A) Abundance (mosquitoes/trap-night), density distribution (mosquitoes/ha), and local spatial clustering of Cx. quinquefasciatus abundance, 2001–2007. (B) Distribution of WNV infections in Cx. quinquefasciatus and location of clusters of high ML WNV infection intensity [Gi*(d)] and presence (Bernoulli test) in mosquito pools (Cx. quinquefasciatus grouped according to date and location) tested during 2001–2007. Large insets show a detailed view of the city of Atlanta, whereas the upper right inset shows the location of Fulton County.

Mentions: Cx. quinquefasciatus was heterogeneously distributed, with the highest abundances (number per trap-night) and densities (numbers per hectare) concentrated within the boundaries of the city of Atlanta (Figure 1A). Traps with elevated abundance of Cx. quinquefasciatus mosquitoes clustered in three locations within an average radius of 1,305 m (range, 200–2,000) from each trap (Figure 1A) [Gi*(d) > 3.7; p < 0.05]. The three high mosquito abundance clusters encompassed segments of five of the seven CSO streams in Atlanta (Figure 1A). High WNV infection intensity in Cx. quinquefasciatus (WNV-positive mosquitoes/1,000) also clustered in three locations within Atlanta (Figure 1B, Gi*(d) > 3.7; p < 0.05). The largest cluster [average radius = 1,042 m (range, 400–2,000)] surrounded part of the North Avenue CSO creek and encompassed 41 trapping locations (Figure 1B). The remaining two clusters encompassed only two trap locations each, with clustering radii of 320 and 93 m, respectively (Figure 1B). Clusters of WNV infection presence in Cx. quinquefasciatus (presence/absence of WNV infection at a trapping location) also occurred within the city of Atlanta, in proximity [average = 988 m (range, 10–3,118)] to CSO streams (Figure 1B) (Kulldorff Bernoulli test, p < 0.05). K-function analysis (Ripley 1976) confirmed that the observed clustering patterns were not the result of heterogeneous trap distribution, because traps were randomly distributed within the city of Atlanta [Supplemental Material, Figure 2B (doi:10.1289/ehp.1001939)].


The risk of West Nile Virus infection is associated with combined sewer overflow streams in urban Atlanta, Georgia, USA.

Vazquez-Prokopec GM, Vanden Eng JL, Kelly R, Mead DG, Kolhe P, Howgate J, Kitron U, Burkot TR - Environ. Health Perspect. (2010)

(A) Abundance (mosquitoes/trap-night), density distribution (mosquitoes/ha), and local spatial clustering of Cx. quinquefasciatus abundance, 2001–2007. (B) Distribution of WNV infections in Cx. quinquefasciatus and location of clusters of high ML WNV infection intensity [Gi*(d)] and presence (Bernoulli test) in mosquito pools (Cx. quinquefasciatus grouped according to date and location) tested during 2001–2007. Large insets show a detailed view of the city of Atlanta, whereas the upper right inset shows the location of Fulton County.
© Copyright Policy - public-domain
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2957916&req=5

f1-ehp-118-1382: (A) Abundance (mosquitoes/trap-night), density distribution (mosquitoes/ha), and local spatial clustering of Cx. quinquefasciatus abundance, 2001–2007. (B) Distribution of WNV infections in Cx. quinquefasciatus and location of clusters of high ML WNV infection intensity [Gi*(d)] and presence (Bernoulli test) in mosquito pools (Cx. quinquefasciatus grouped according to date and location) tested during 2001–2007. Large insets show a detailed view of the city of Atlanta, whereas the upper right inset shows the location of Fulton County.
Mentions: Cx. quinquefasciatus was heterogeneously distributed, with the highest abundances (number per trap-night) and densities (numbers per hectare) concentrated within the boundaries of the city of Atlanta (Figure 1A). Traps with elevated abundance of Cx. quinquefasciatus mosquitoes clustered in three locations within an average radius of 1,305 m (range, 200–2,000) from each trap (Figure 1A) [Gi*(d) > 3.7; p < 0.05]. The three high mosquito abundance clusters encompassed segments of five of the seven CSO streams in Atlanta (Figure 1A). High WNV infection intensity in Cx. quinquefasciatus (WNV-positive mosquitoes/1,000) also clustered in three locations within Atlanta (Figure 1B, Gi*(d) > 3.7; p < 0.05). The largest cluster [average radius = 1,042 m (range, 400–2,000)] surrounded part of the North Avenue CSO creek and encompassed 41 trapping locations (Figure 1B). The remaining two clusters encompassed only two trap locations each, with clustering radii of 320 and 93 m, respectively (Figure 1B). Clusters of WNV infection presence in Cx. quinquefasciatus (presence/absence of WNV infection at a trapping location) also occurred within the city of Atlanta, in proximity [average = 988 m (range, 10–3,118)] to CSO streams (Figure 1B) (Kulldorff Bernoulli test, p < 0.05). K-function analysis (Ripley 1976) confirmed that the observed clustering patterns were not the result of heterogeneous trap distribution, because traps were randomly distributed within the city of Atlanta [Supplemental Material, Figure 2B (doi:10.1289/ehp.1001939)].

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Environmental Studies, Emory University, Atlanta, Georgia 30322, USA. gmvazqu@emory.edu

ABSTRACT

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.

Objectives: 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.

Materials and 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.

Show MeSH
Related in: MedlinePlus