West Nile Virus
West Nile virus (WNV) is the most common mosquito-borne disease in Kansas and the United States. Several species of mosquitoes are responsible for transmission of arboviruses, but Culex species are the primary vector in Kansas and the United States. The risk of acquiring WNV infection depends on various factors including:
- Time of year
- Number and location of infected mosquitoes
- Number of days with sufficient heat
Warm temperatures increase the rate of mosquito larvae development, which increases the mosquito population size. The risk of WNV transmission is lower in the spring, but rises through the early and midsummer months, and usually reaches peak transmission during July, August, and September.
West Nile Virus Weekly Risk Assessment Map & Data Dashboard
This map contains a weekly snapshot of the risk of being bitten by a mosquito carrying West Nile Virus during peak season, which is July through September. The data will be updated weekly on Friday. Learn what the risk levels mean and what you can do to prevent mosquito bites in the section below the map. View the West Nile Virus Data Dashboard.
Risk Assessment - What It Means & What You Can Do
High Risk Week
High risk means that you are at a high risk of being bitten by a mosquito that could be carrying West Nile, based on a high number of mosquitoes identified and a high number of historical human cases. Do the following to prevent mosquito bites:
- People over 50 or people who are immunocompromised may want to adjust outdoor activity to avoid peak mosquito hours, which is from dusk to dawn
- Wear mosquito repellent
- Wear long sleeves and long pants when weather permits
- Use mosquito netting on baby carriages and playpens
- Dump standing water twice weekly
Moderate Risk Week
Moderate risk means there is a moderate possibility of being bitten by a mosquito that could be carrying West Nile. Do the following to help prevent mosquito bites:
- Wear mosquito repellent
- Wear long sleeves and long pants when weather permits
- Use mosquito netting on baby carriages and playpens
- Dump standing water twice weekly
Low Risk Week
Low risk means that mosquitos that could be carrying West Nile are low in number. There is a low probability of being bitten by an infected mosquito. Do the following to prevent mosquito bites:
- Wear mosquito repellent from dusk to dawn
- Wear long sleeves and long pants from dusk to dawn
- Use mosquito netting on baby carriages and playpens
- Dump standing water once
Minimal Risk Week
Minimal risk means there is a low probability of being bitten by an infected mosquito; however, this does not mean the risk is zero. Do the following to prevent mosquito bites:
- Keep screens or windows and doors in good repair
- Use air conditioning if you have it
- Reduce mosquitoes around your home by emptying standing water from flowerpots, gutters, buckets, tarps, water dishes, discarded tires, and birdbaths on a regular basis
Mosquito Bite Prevention
Drain Standing Water
Eliminate standing water where mosquitoes live and breed.
- Empty standing water from tarps, old tires, buckets, and other places where rainwater collects. Use larvicide in low-lying areas where water cannot be removed.
- Refresh water for bird baths, pet bowls, and wading pools at least every three days.
Dress for Prevention
- Cover your skin with clothing when outdoors
- Wear long sleeves and pants when practical
- Limit outdoor activities when mosquitoes are most active
Mosquito Repellant with DEET
When used as directed, EPA-approved insect repellents are proven safe and effective, even for pregnant and breastfeeding women. Use insect repellents that contain DEET or other EPA-approved repellents. Learn more about methods to control mosquitos.
Surveillance & Risk Assessment
Learn more about surveillance and risk assessment, and find resources and contact information for KDHE's Epidemiology team.
Mosquito Surveillance
In 2017, the Kansas Department of Health and Environment, with funding from the Centers of Disease Control and Prevention, expanded the mosquito surveillance from 1 to 3 counties (Reno, Sedgwick, and Shawnee). These counties will continue to participate in surveillance in 2022. In addition, we collect mosquito surveillance data from 3 additional partners throughout the state. Mosquito surveillance began on June 27, 2022 and will continue through mid-October 2022.
Risk Assessment
In 2022, 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.
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Epidemiology Hotline
Phone: : 877-427-7317