Surveillance

A good adult mosquito surveillance program is perhaps the cornerstone of mosquito management and control.  Surveillance involves trapping and counting mosquitoes, identifying the species, and performing disease testing on the mosquitoes.

The Franklin County Board of Health takes a proactive approach to mosquito management by performing weekly adult mosquito surveillance.  We do this by setting 38 mosquito traps in various locations throughout the county.  The traps include 33 gravid traps and 5 CDC light traps.  These traps are set from mid-May through mid-October and remain in the same location.  The species of mosquitoes collected in the traps are counted and identified by our staff.  The mosquito species that carry West Nile virus (WNV) are divided into “pools” or groups of fifty (50) and are then tested for the presence of WNV.  Many of the mosquito pools collected are tested at our facility by using RAMP (Rapid Analyte Measurement Platform).  This enables us to have WNV test results within hours as opposed to days or weeks.  During the peak of the West Nile virus transmission cycle this in-house testing is invaluable, providing us one of the tools that help us determine when it is appropriate to adulticide or spray an area to control adult mosquitoes.  All of the mosquito pools collected, including those that have been RAMP tested are confirmed by the Ohio Department of using RT-PCR (Real-time polymerase chain reaction).  In addition, when species of mosquitoes that carry La Crosse encephalitis are identified, they will be sent to the Connecticut Agricultural Experiment Station for virus isolation and testing.

Types of Traps

Gravid Trap The gravid trap is our primary trap type which is designed specifically to target the culex mosquito which can carry West Nile virus.  The trap has a reservoir of stagnant water and organic material with a small battery powered fan and a net above it.  The culex mosquito prefers to lay their eggs in this type of water and are attracted its smell.  As the female mosquito attempts to lay her eggs on the surface of the water, they are drawn into the net by the small motorized fan.  These traps are set in the late afternoon and collected the next morning.

CDC Light Trap The CDC light trap target mosquitoes looking for a blood meal.  When a mosquito is searching for someone to bite, they are attracted and sense the carbon dioxide (CO2) that mammals and humans exhale.  The light trap uses as a small light bulb, dry ice to produce CO2, a small motorized fan and a net.  As the mosquito approaches the light and source of CO2 they are drawn into the net by the small fan and captured.  These traps are set for a period of 24 hours and then collected.  We set five of these traps per week.

Franklin County Mosquito Surveillance data:

2009
2008
2007- 2004

National surveillance and disease maps.