Volume 87, Issue 6
  • ISSN: 0002-9637
  • E-ISSN: 1476-1645



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 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 abundance in the outbreak area. Twenty-eight WNV TaqMan reverse transcription-polymerase chain reaction–positive mosquito pools were identified, including 24 of , 3 of , and 1 of sp. However, WNV infection rates did not differ between outbreak and control sites. At outbreak sites, 30 of 39 engorged 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 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 and human hosts in the outbreak area compared with the control area.


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  • Received : 09 Nov 2011
  • Accepted : 25 Aug 2012
  • Published online : 05 Dec 2012

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