The Johnson County Department of Health and Environment (JCDHE) conducted mosquito surveillance in 2016 and 2017 at four locations in Johnson County, KS to monitor the presence of mosquito species that can transmit diseases like the West Nile and Zika viruses. JCDHE contracted with the Kansas Biological Survey to conduct trapping and laboratory analytical activities. The Kansas Department of Health and Environment provided additional resources to test mosquito specimens from Johnson County for the presence of West Nile virus, which is the mosquito-borne disease of greatest concern in Johnson County.
What does the data mean?
Fluctuations in local mosquito populations occur naturally through the spring, summer and fall. Because mosquitos require standing water to reproduce, variations in rainfall can have a significant impact on the size of local populations. In general, you would expect to see greater numbers of mosquitos during an unusually wet summer than you would during an unusually dry summer. It is not unusual to see mosquito populations spike following a period of rain.
There are two genera, or families, of mosquitos that are represented in the data table:
- Culex genus mosquitos are common throughout most of the U.S. and can transmit diseases like West Nile virus, chikungunya, dengue, and malaria. In Johnson County, West Nile virus is the primary mosquito-borne illness of concern. At this time, chikungunya, dengue and malaria are not present locally and tend to occur in more tropical areas.
- Aedes genus mosquitos are also present throughout the southeastern U.S., and their range extends into the Kansas City metro area. The two that can transmit the Zika virus are Aedes aegypti and Aedes albopictus. Of the two species, Aedes aegypti is more efficient at spreading Zika because it takes blood meals exclusively from humans, where Aedes albopictus feeds on both humans and other animals. In the mosquito surveillance conducted by JCDHE, no specimens of Aedes aegypti were found in Johnson County, therefore the risk of contracting Zika through a mosquito bite is exceedingly low.
Zika would only become a concern in Johnson County if a traveler from an area where Zika is common had the virus and then received a bite from a local Aedes mosquito. That mosquito could then pass the virus on to the next person it bites. Because local transmission can occur in this way, it is important for Johnson County residents who have been in a Zika-affected area to wear mosquito repellant for three weeks after returning, even if they are not experiencing any symptoms of illness.
What can I do?
1. Your best defense is to prevent mosquito bites. Use an EPA-registered insect repellent as directed. If you are using sunscreen, apply the sunscreen first and then the insect repellent. Wear clothing that covers arms and legs. Cover a crib, stroller or baby carrier with mosquito netting. Around the home, empty any outdoor container that has standing water, keep your windows and doors shut and make sure window or door screens are in good condition with no holes.
2. Pregnant women and couples considering becoming pregnant should avoid travel to places where there is active Zika virus transmission. A list of these locations can be found here. Non-pregnant couples who have traveled to an area with active Zika virus transmission are advised to wait 6 months before trying to conceive because Zika virus can stay in semen longer than in other body fluids.
3. Anyone concerned about getting or passing Zika virus through sex should use condoms every time they have sex or do not have sex.
The Centers for Disease Control and Prevention offer a variety of online resources for those who want to learn more about mosquito-borne diseases and how to prevent them.