Vector Index Log
The vector index tell us the relative risk of West Nile virus transmission. The vector index is based on the:
Total number of Culex Pipien and Culex Tarsalis – the species that carry West Nile virus
Number of infected mosquitoes across an areaWe calculate the vector index by determining the average number of infected mosquitoes collected per trap in an area. Emergency spraying may be recommended when the vector index is at 0.75 or higher.