PubMed

Chung WM, Buseman CM, Joyner SN, Hughes SM, Fomby TB, Luby JP, Haley RW. (2013) The 2012 West Nile encephalitis epidemic in Dallas, Texas. JAMA, 310(3): 297-307.

Abstract
After progressive declines over recent years, in 2012 West Nile virus epidemics resurged nationwide, with the greatest number of cases centered in Dallas County, Texas.

RESULTS:
The investigation identified 173 cases of WNND, 225 of West Nile fever, 17 West Nile virus-positive blood donors, and 19 deaths in 2012. The incidence rate for WNND was 7.30 per 100,000 residents in 2012, compared with 2.91 per 100,000 in 2006, the largest previous Dallas County outbreak. An unusually rapid and early escalation of large numbers of human cases closely followed increasing infection trends in mosquitoes. The Cx quinquefasciatus species-specific vector index predicted the onset of symptoms among WNND cases 1 to 2 weeks later...

CONCLUSIONS AND RELEVANCE:
Large West Nile virus epidemics in Dallas County begin early after unusually warm winters, revisit similar geographical distributions, and are strongly predicted by the mosquito vector index. Consideration of weather patterns and historical geographical hot spots and acting on the vector index may help prevent West Nile virus-associated illness.