Protective Behavior and West Nile Virus Risk

We conducted a cross-sectional, household survey in Oakville, Ontario, where an outbreak of West Nile virus (WNV) in 2002 led to an unprecedented number of cases of meningitis and encephalitis.Practicing >2 personal protective behavior traits reduced the risk for WNV infection by half. L ittle is known about risk factors for infection with WestNile virus (WNV).Data about the effect of personal protective behavior traits recommended by public health agencies, such as wearing long sleeves and long pants, using mosquito repellent, and avoidance of mosquito areas, are sparse (1).A household-based seroprevalence survey in Oakville, Ontario, where a large outbreak of WNV occurred in the summer of 2002, allowed us to assess modifiable risk factors for WNV infection.Oakville is located in Halton, a region that had the highest reported incidence of clinical WNV infection in Ontario in the 2002 season.Sixty cases (58 confirmed and 2 probable) occurred in a population of almost 400,000, with onset during the months of August and September 2002 (Figure 1).A peak in dead crow sightings in Halton (600 per week) occurred 5 weeks before the peak in human cases.Within this region, most cases occurred in south Oakville, in the L6L and L6K forward sortation areas (FSAs, i.e., the first 3 digits of the postal code) (Figure 2).We hypothesized that personal protective and source-reduction behavior would be associated with reduced risk for WNV infection.