Behavioral Risks for West Nile Virus Disease, Northern Colorado, 2003

Indira B Gujral,Emily C Zielinski-Gutierrez,Roger Nasci,Adrienne Lebailly

doi:10.3201/eid1303.060941

Indira B Gujral, Emily C Zielinski-Gutierrez + Show 2 more

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https://doi.org/10.3201/eid1303.060941

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Abstract

In 2003, residents in 2 adjacent cities in northern Colorado (Loveland and Fort Collins) had severe outbreaks of human West Nile virus (WNV) disease. Unexpectedly, age-adjusted neuroinvasive disease rates were higher in Loveland (38.6 vs. 15.9 per 100,000), which had a more extensive mosquito control program and fewer mosquitoes. A survey was conducted to assess differences in personal protection and risk practices by each city's residents. During May and June 2004, a random-digit dial telephone survey was conducted among adults to assess personal protection behavioral practices used to prevent WNV infection during the 2003 outbreak. After we adjusted for identified risk factors, Loveland residents were 39% more likely to report seldom or never using N,N-diethyl-m-toluamide (DEET), and approximately 30% were more likely to report being outdoors during prime mosquito-biting hours than Fort Collins residents. Personal protective practices may directly influence rates of WNV infection and remain important even when comprehensive community mosquito control measures are implemented.

Highlights

In 2003, residents in 2 adjacent cities in northern Colorado (Loveland and Fort Collins) had severe outbreaks of human West Nile virus (WNV) disease
In the United States, the mantra familiar to public health workers and residents living in West Nile virus (WNV)–affected areas is to practice the 4 Ds of prevention: 1) DEET (N,N-diethyl-m-toluamide): wear an insect repellent containing DEET; 2) dress: wear long sleeves and long pants; 3) drain: drain standing water around the home; and 4) dusk to dawn: limit time outdoors during this time
During the 1999 WNV outbreak on Staten Island, New York, a serosurvey conducted by Mostashari et al found the highest seroprevalence of WNV among persons who spent >2 h outdoors from dusk to dawn; persons were even more likely to be seropositive if they reported never using a repellent containing DEET [11]

Summary

Introduction

In 2003, residents in 2 adjacent cities in northern Colorado (Loveland and Fort Collins) had severe outbreaks of human West Nile virus (WNV) disease. The city of Loveland had a much higher age-adjusted rate of neuroinvasive disease (38.6/100,000) than the city of Fort Collins (15.9/100,000); standardized risk ratio 2.43 (95% confidence interval [CI] 1.21–4.87, p

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