Interventions: vector control and public education: panel discussion

West Nile virus in North America: perspectives on epidemiology and intervention

West Nile virus (WNV) invaded New York in 1999 and rapidly swept across the North American continent to the West Coast, north into southern Canada and south into Latin America, with minimal genetic change. Regional epidemics in equines and humans typically have included a year of viral introduction with minimal activity, successful overwintering, explosive amplification to epidemic levels the following year and then rapid subsidence. Overwintering possibly included long-term mosquito or avian infections, continued low-level transmission at southern latitudes and dispersal by south-north migrants. Explosive amplification has been associated with infections in several corvid species and other urban birds that produce elevated viremias capable of efficiently infecting even moderately susceptible mosquito species. Intervention has included mass vaccination of equines, and proactive and reactive mosquito control. Proactive mosquito control in areas with established infrastructure has been successful in reducing case incidence.

West Nile Virus: the buzz on Ottawa residents' awareness, attitudes and practices

BACKGROUND

In 2002, the City of Ottawa was interested in the public perception of West Nile Virus (WNV) and mosquito control. Their objectives were to assess: awareness of WNV, practices to reduce mosquito sources, personal protective measures, and attitudes towards community-based insecticide programs.

METHODS

In July 2002, we administered a telephone survey to a random, stratified sample of urban, suburban and rural Ottawa households.

RESULTS

Surveys were completed for 491 households. Most (77.2%) respondents reported they had heard of WNV, and of these, 58.3% reported WNV was an important health issue. Mosquito repellent was the most common personal protective measure, reported among 72.5% of respondents, of whom 76.9% used DEET products. Multivariate regression analyses showed that age was a significant predictor of repellent use, with respondents aged less than 51 years more likely to use repellent than older respondents (ORadj =2.0; 95% CI: 1.2-2.3). This age group was also more likely to use at least one personal protective behaviour (ORadj = 2.5; 95% CI: 1.4-4.5). Of 315 people selecting a justified time to larvicide, 4.8% chose "larvicides should never be used in Ottawa"; 33.4% stated that larviciding would be appropriate "when WNV was detected in birds or mosquitoes"; one third "needed more information" on the health and environmental effects of insecticides, prior to selecting a response.

CONCLUSIONS

Our findings highlight the need for public education reinforcing WNV importance, emphasizing the health and environmental effects of insecticides as well as appropriate personal protective behaviours. Such messages should target older and urban residents.