West Nile Virus Finally Debuts in British Columbia 10 Years After Its Introduction to North America

Since its first detection in New York (1999), West Nile virus (WNv) has spread across the United States and Canada with the first activity reported in Canada in 2001. By 2004, WNv had been detected almost in every province of Canada and the contiguous regions of the United States with the exception of British Columbia (BC), this despite being detected in Alberta in 2003 and Washington as early as 2002. In August 2009, two human cases were serologically found to have WNv infection. They reported mosquito bites and had only traveled in the South and Central Okanagan areas of BC before their presentation. On the basis of clinical, laboratory, and epidemiological data, these two human cases have been confirmed as the first locally acquired WNv cases in BC. Various factors may have contributed to the 10-year delay in the spread of WNv to BC, including regional weather conditions and unique topography.