The Mosquito Surveillance and Control Program

Mosquito Surveillance and Control Program

Disease spread by mosquitos is a concern.  In response, the Clark County Combined Health District cooperates with the Ohio Department of Health and other local health departments throughout the state with our monitoring and control program. 

Our surveillance team uses two different brands of mosquito traps to collect samples of mosquitos for testing. Mosquitos are collected from 12-15 locations within Clark County once or twice per week throughout the mosquito season. Mosquitos collected are counted, sorted by species and tested for a number of diseases by the Ohio Department of Health. With this information, our mosquito surveillance team is able to pinpoint locations of concern, take appropriate control actions, inform the public when a mosquito collection has tested positive for a certain disease, and confirm the effectiveness of control activities.

The best method of control is to limit the conditions that allow mosquitos to breed.  Mosquitos lay eggs in standing water. Our staff responds to complaints of standing water and works with homeowners and local authorities to eliminate standing water in ditches, stagnant swimming pools, and other items commonly found around homes.  Standing water that can’t be drained may be treated with mosquito larvicide.  Larvicide contains natural bacteria which neutralize mosquito larvae before they grow into adults.  When monitoring shows that reducing breeding sources and larviciding has not had enough effect, misting may be performed to reduce the adult population.  Misting may also be performed when monitoring reveals a positive test for West Nile Virus or other mosquito-borne disease.  Misting is accomplished with a misting machine that is driven slowly on the streets at night to release a cloud of dilute mild insecticide, usually Permethrin. Misting will not work during the day as the cloud will dissipate. The cooler night temperatures allow the mist to remain close to the ground long enough to kill the mosquitos. The mist will be dissipated by morning and will not cause harm to people, plants, or animals.

How to Protect Yourself

1.)    Use mosquito repellent when outdoors!
The simplest way to protect yourself and your family from mosquito bites and the diseases that they can carry is to use EPA-registered mosquito repellents and closely follow the directions. Repellents containing DEET will provide the most protection. You can also protect yourself even further by wearing long pants and longs sleeves; essentially the more you cover up, the less chance you have of being bitten.

2.)    Eliminate standing water around your home
Mosquitos love to lay their eggs in stagnant water. To avoid contributing to the mosquito population, check for things in and around your home that tend to collect rainwater such as: old tires, buckets, toys, containers, clogged rain gutters, etc. In addition to this, things like bird baths, rain barrels, decorative ponds, or swimming pools should either maintain circulation or be cleaned out regularly.

3.)    Make your home a “mosquito-free zone”
Keep windows and doors closed, or at least screened to keep mosquitos out. Make sure screens are installed properly and regularly check them for holes or openings where mosquitos may be able to get through.

4.)    Personal use of insecticides
If the mosquito population in or around your home becomes too much to handle, you may decide to use an insecticide. It may be easier and safer to contract a pest control agency to do the work, but if you choose to do the task yourself, it is suggested that you check out this information provided by the Centers for Disease Control and Prevention (CDC):

5.)    Traveling to an affected area?

  • Be aware of the disease status in the area in which you are traveling by checking the CDC website for travel advisories, Pregnant women should avoid traveling to areas affected by the Zika virus!
  • Protect yourself by wearing bug repellent, covering up with clothing and using mosquito netting around bed if available.
  • If you become ill, contact your health provider immediately and inform them of the areas that you have traveled to.

Relevant Mosquito-transmitted Diseases in Our Area

According to the Ohio Department of Health, the diseases that may be transmitted by mosquitos in our area include: Eastern equine encephalitis (EEEV), La Crosse virus (LACV), St. Louis encephalitis virus (SLEV), and West Nile Virus (WNV). More information on these viruses can be found via the following links:


Diseases that can occur in our area due to acquisition during travel include: Chikungunya virus (CHIKV), Dengue virus (DNV), Japanese encephalitis virus (JEV), Malaria, Yellow fever virus (YFV), and Zika Virus (ZikV). More information on these viruses can be found via the following links:

Malaria -
ZikV -


Last Reviewed: 11/14/2017 cc