West Nile virus range expansion into British Columbia.

The research article describes how the West Nile Virus (WNV) spread into the British Columbia province in Canada in 2009 due to favourable environmental conditions, putting both humans and horses at risk.

Introduction and Objective

The research was done following the detection of West Nile virus (WNV) into British Columbia, a province of Canada, in 2009. The objective of this research was to understand how and why the WNV managed to spread into this province.

Methodology

In the wake of the WNV discovery in British Columbia, a series of tests were conducted for confirmation. These included:

• ELISA (enzyme-linked immunosorbent assay) and plaque-reduction neutralization tests were conducted to confirm infection in two people and three horses.
• Ten mosquito pools were studied using the reverse transcription polymerase chain reaction (RT-PCR) to confirm the presence of the WNV.

Findings and Discussion

The research found that the WNV activity was majorly observed in the southern Okanagan Valley of British Columbia, areas characterized by hot and dry climates. The research suggests:

• That the spread and multiplication of the WNV was facilitated by unusual high nightly temperature and accumulation of degree-days in the late summer.
• The estimated exposure dates for the virus among humans and the initial detection of WNV in mosquitoes occurred simultaneously with a late summer upsurge of Culex tarsalis mosquitoes in the southern Okanagan Valley.
• Culex tarsalis mosquitoes are known to spread the western equine encephalitis virus, implying a potential role in spreading the WNV.

Implications and Conclusion

The research underscores how temperature and mosquito abundance, specifically that of Cx. tarsalis, may play a pivotal role in confining the transmission of WNV. This finding is particularly insightful for regions sharing similar geographic conditions as that of the southern Okanagan Valley in British Columbia. Future efforts need to focus on controlling the population of Cx. tarsalis mosquitoes, particularly during late summer, as a potential approach towards preventing the spread of WNV.