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. 2012 Dec;87(6):1125-31.
doi: 10.4269/ajtmh.2012.11-0700. Epub 2012 Oct 29.

Entomologic investigations during an outbreak of West Nile virus disease in Maricopa County, Arizona, 2010

Marvin S Godsey Jr  1 , Kristen Burkhalter, Ginger Young, Mark Delorey, Kirk Smith, John Townsend, Craig Levy, John-Paul Mutebi
Affiliations

Entomologic investigations during an outbreak of West Nile virus disease in Maricopa County, Arizona, 2010

Marvin S Godsey Jr et al. Am J Trop Med Hyg. 2012 Dec.

Abstract

Entomologic investigations were conducted during an intense outbreak of West Nile virus (WNV) disease in Maricopa County, Arizona during July 31-August 9, 2010. The investigations compared the East Valley outbreak area, and a demographically similar control area in northwestern metropolitan Phoenix where no human cases were reported. Five mosquito species were identified in each area, and species composition was similar in both areas. Significantly more Culex quinquefasciatus females were collected by gravid traps at Outbreak sites (22.2 per trap night) than at control sites (8.9 per trap night), indicating higher Cx. quinquefasciatus abundance in the outbreak area. Twenty-eight WNV TaqMan reverse transcription-polymerase chain reaction-positive mosquito pools were identified, including 24 of Cx. quinquefasciatus, 3 of Psorophora columbiae, and 1 of Culex sp. However, Cx. quinquefasciatus WNV infection rates did not differ between outbreak and control sites. At outbreak sites, 30 of 39 engorged Cx. quinquefasciatus had fed on birds, 8 of 39 on humans, and 1 of 39 on a lizard. At control sites, 20 of 20 identified blood meals were from birds. Data suggest that Cx. quinquefasciatus was the primary enzootic and epidemic vector of this outbreak. The most important parameters in the outbreak were vector abundance and blood meal analysis, which suggested more frequent contact between Cx. quinquefasciatus and human hosts in the outbreak area compared with the control area.

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Figures

Figure 1.
Figure 1.
Locations of six outbreak sites in the southeastern Phoenix, Arizona, metropolitan area (East Valley), the focus of a West Nile virus disease outbreak in 2010, and six control sites in the northwestern metropolitan area, where no human cases occurred.
Figure 2.
Figure 2.
Epidemic curve of the West Nile virus outbreak in Maricopa County, Arizona, in 2010, with the mosquito sampling interval denoted. Cases are listed by week of disease onset. MMWR = Morbidity and Mortality Weekly Report.
See this image and copyright information in PMC

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