Barriers to West Nile Virus (WNV) Prevention Among Maryland Adults 60 Years of Age and Older

BACKGROUND: West Nile Virus (WNV) is endemic in Maryland, and adults ≥60 years old are at highest risk of severe disease. Understanding barriers to WNV prevention in this group is vital. We examined knowledge, attitudes, and behaviors of Maryland residents ≥60 years old toward WNV, to identify barriers to implementing prevention measures, and to explore acceptance of a WNV vaccine. We hypothesized that persons ≥60 years old who received information about WNV in the last year are more likely to practice ≥1 personal protective behavior (PPB); persons ≥60 years old who perceive WNV as serious are more likely to support community mosquito control; and persons ≥60 years old who perceive themselves susceptible to WNV are more likely to accept WNV vaccination, if available.

METHODS: We conducted a cross-sectional telephone survey of a stratified random sample of 1,700 households in zip codes with >2 human WNV cases from 2006-2011 and a head of household ≥60 years old.  Survey questions operationalized Health Belief Model (HBM) constructs: perceived severity, perceived susceptibility, and perceived barriers. Using STATA v.12.1, we assessed associations between demographics and PPBs and tested hypotheses via Chi-square and Fisher’s exact tests.

RESULTS: We enrolled 211 participants with mean age 70 years (range 60-99). Most were white (79%) with Bachelor’s or higher degrees (51%). Although 59% received WNV information in the last year, this was not significantly associated with using repellent or draining standing water. Although 96% of respondents perceived WNV as serious, only 29% sometimes or always used repellent in the previous 90 days. Overall, 84% favored community mosquito control and 70% expressed acceptance of a WNV vaccine. Barriers to using PPBs included sensitivity to repellent (24%) and feeling immune to mosquito bites (17%). Individuals who received WNV information were not significantly more likely to practice ≥1 PPB (odds ratio [OR] 1.91, 95% CI 0.63-5.77); and individuals perceiving WNV as serious were not significantly more likely to favor community mosquito control (OR 4.58, 95% CI 0.82-25.74).  Those who perceived themselves susceptible to infection had significantly higher odds of vaccine acceptance (OR 3.28, 95% CI 1.36-7.91).

CONCLUSIONS: Willingness to accept a WNV vaccine was high, but awareness of WNV as serious does not reliably result in PPB practice.  Receiving information about WNV was not sufficient for PPB practice. However, when individuals felt susceptible, they were more likely to support prevention measures such as receiving vaccination, suggesting a benefit from enhancing risk communications.