Risk Assessment

WNV risk levels have been developed for Kansas based on the following criteria:

• Presence and abundance of Culex spp. of mosquitoes.
• Average temperature for the previous two weeks.
• Historical data indicators for the weeks of increased WNV human cases.

Regardless of the West Nile virus risk level for your area, there is no such thing as being 'risk-free'. Take precautions when you are out in areas where mosquitoes are present.

Methods for Risk Assessment

We utilize three factors in our risk assessment model; temperature, mosquito surveillance data, and human cases of WNV, however, for the present risk assessment model, mosquito surveillance data is not utilized in the western regions. Each factor has set benchmarks and each benchmark is assigned a value. The values from these three categories are averaged. The average rating is assigned a WNV risk level for each week. The three factors are as follows:

• High-risk environmental conditions include above-normal temperatures with or without above-normal rainfall. We use the average daily temperature during the prior 2 weeks as our benchmark.
• Culex species of mosquitoes serve as the main source of WNV transmission to people and horses. Relative abundance of Culex species mosquitoes compared to the same week in the previous year and the number of Culex species mosquitoes are evaluated each week. Greater than 40 Culex species mosquitoes collected in a week increases this factor to its maximum value. 
• Number of human cases of WNV each week based on the average number of cases in the previous five years.