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SOUTH DAKOTA DEPARTMENT OF HEALTH
FOR IMMEDIATE RELEASE: Friday, July 27, 2007
FOR IMMEDIATE RELEASE: Friday, July 27, 2007
CONTACT: Dr. Lon Kightlinger, Health Department, (605) 773-3737
Dr. Jim Wilson, SDSU Cooperative Extension, (605) 688-4752
New research showing when WNV mosquitoes most active
PIERRE, S.D. – Thanks to newer, more sophisticated mosquito traps, local mosquito control programs can now not only trap mosquitoes but also determine what hours they’re most active.
The new traps provide additional information to an existing mosquito surveillance program jointly conducted by South Dakota State University and the South Dakota Department of Health. As part of the program, mosquitoes are trapped in several South Dakota communities and tested for West Nile virus (WNV) at the state Public Health Laboratory and the SDSU Laboratory. The surveillance is designed to help guide local control efforts by enabling them to focus their adulticiding efforts around the peak WNV transmission season.
Dr. Jim Wilson, Cooperative Extension Pesticide Education Coordinator, said that the newer rotator-type traps are being used in a few strategic locations in the state to study peak times of the day when mosquito activity is highest.
The rotator trap makes it possible to separate daily collections into different time periods because it uses a programmable timer to rotate individual collection cups to the trap at 2 hour intervals.
“We know that Culex tarsalis mosquitoes are the primary carrier of West Nile in South Dakota. The research is still very preliminary, but the rotator traps are indicating that as much as 50% of Culex activity is occurring in the two-hour period between 10 p.m. and 12 a.m,” said Wilson. “This knowledge can really help mosquito control programs target their efforts most effectively.”
“This is important new information for mosquito control programs but it doesn’t negate the importance of people practicing preventive measures such as mosquito repellent whenever they’re outside,” said Dr. Lon Kightlinger, State Epidemiologist for the Department of Health. “People often use mosquito repellents at dusk when the nuisance mosquito, Aedes vexans is most active. Results from these recent studies reniforce the need to use repellents throughout the evening hours.”
The department recommends the following precautions to prevent mosquito bites and reduce the risk of WNV:
- Use mosquito repellents containing DEET, picaridin or oil of lemon eucalyptus, and cover as much skin as possible with loose-fitting clothing.
- Limit time outdoors at night when mosquitoes are most active.
- Eliminate standing water that gives mosquitoes a place to breed.
- Support local mosquito control efforts.
Elderly persons, pregnant women, diabetics, transplant patients, individuals with high blood pressure, and those with a history of alcohol abuse should be especially mindful to take precautions. People with a severe or unusual headache should see their physician.
As of July 25, South Dakota had reported 29 human cases of WNV, including 1 death. Those cases have been reported in 19 counties: Beadle 2, Brown 3, Campbell 1, Clay 1, Davison 3, Day 1, Edmunds 2, Grant 1, Hand 2, Hanson 1, Hughes 3, Kingsbury 1, Lincoln 2, Minnehaha 1, Shannon 1, Todd 1, Tripp 1, Turner 1, and Walworth 1.
For more information about West Nile, visit the Department of Health web site at http://doh.sd.gov/WestNile/ or call 1-800-592-1861. Information is also available from the SDSU Cooperative Extension Service at http://sdces.sdstate.edu/westnile/ and the South Dakota Animal Industry Board at www.state.sd.us/aib.