NORTHWEST MOSQUITO ABATEMENT DISTRICT

147 W. Hintz Rd.

Wheeling, IL. 60090

Phone: (847) 537-2306

Fax: (847) 537-2583

www.nwmadil.com

 

Mosquito Update

August 15, 2006

 

 

WEST NILE VIRUS HUMAN CASES

Currently, 3 human West Nile virus (WNV) cases have been confirmed by the Illinois Department of Public Health.  Two of the cases confirmed were from suburban Cook County and the other from St. Clair County. 

 

WEST NILE VIRUS WARNINGS INCREASE!

The Illinois Department of Public Health and Cook County Department of Public Health have released warnings regarding the rapidly increasing risk of WNV to humans.  As the summer progresses it is of utmost importance that cities, villages and municipalities continue their warnings to residents regarding the threat of West Nile virus and strongly advocate mosquito avoidance, protection and stagnant water elimination. 

 

Director’s Note:

2006 is the first true “wet” summer since the introduction of WNV into Illinois back in 2001.  Typically, human WNV & Saint Louis encephalitis outbreaks have been associated with extended, hot-dry periods.  “Wet” seasons usually result in above average nuisance floodwater mosquitoes and lower Culex populations due to wash-outs of typical stagnant water habitats and underground sewer systems.  Sizable, periodic rainfalls approximately every 10 days (experienced thus far in Cook County, 2006) may even be somewhat detrimental to the proliferation of flavivirus vectors due to the wash-out factor.  Alternately, additional rainfall may create even more stagnant water sites if the heat returns and conditions start to dry down.  Right now it is anybodies guess on how WNV will respond to the current “wet” conditions especially considering WNV appears better acclimated to Chicago land latitude than St. Louis encephalitis is.   We do know that cool summers like in 2004 (and, in part 2003) apparently resulted in fewer human WNV cases despite continued, widespread avian/mosquito WNV amplification

 

PRESENT CONTROL STATUS:

NUISANCE MOSQUITO CONTROL

Nuisance mosquito numbers remain low averaging below our nuisance threshold of 35 female Aedes vexans per New Jersey light trap.  Control efforts and recovery from the previous 4 drought years are responsible for the low numbers.  Public nuisance mosquito complaints have been low or from isolated areas.

 

CULEX MOSQUITOES

Culex mosquito numbers have decreased due to control efforts focusing on Culex production sites.  Elevated temperatures accelerate Culex development in stagnant water areas as well as the risk for WNV.   Recent rains will once again provide additional Culex stagnant water production areas (for examples see:  http://www.nwmadil.com/breeding sites1.htm).  Residents are strongly advised to inspect & eliminate all stagnant water areas from their properties that may produce these mosquitoes every week through the months of July-September.  Any container that holds water and organic debris for greater than 7 days can produce many of these mosquitoes. 

 

Stagnant water mosquito producing sites (detention/retention ponds, ditches, building foundations & container sources) will be treated with the microbial insecticide Bacillus sphaericus and the insect growth regulator methoprene (a.k.a. Altosid).   We are continuing our second treatment of street catch basins throughout the District with Altosid Ingots (methoprene).

 

MOSQUITO VIRUS SURVEILLANCE IN ILLINOIS

NWMAD has tested (VecTest & PCR) 953 batches of mosquitoes for West Nile Virus, St. Louis and Eastern Equine encephalitis.  272 infected batches of mosquitoes have been detected thus far.  We will continue to ship out samples for confirmatory testing by Illinois Natural History RT-PCR testing.

 

The Illinois Department of Public Health (IDPH) reports:  48 counties with mosquitoes or birds testing positive for WNV.   

 

Mosquito batches testing positive in the District are posted at the NWMAD website http://www.nwmadil.com/VECTEST1.htm.

 

ADULTICIDING (Night Spraying Operation):

All Townships within the NWMAD territory have been sprayed based on the detection of repetitive WNV infected mosquito samples.  To date, Townships and/or parts of Townships have been sprayed on the following dates based on infected mosquito surveillance and Culex mosquito abundance:

 

Barrington Township: 8/3

Elk Grove Township: 7/13, 7/18, 7/27, 8/3, 8/7,  

Hanover Township:  7/18, 7/26, 8/8

Maine Township:  7/18, 7/26, 8/3, 8/4, 8/7

Western NWMAD portion of Village of Northbrook: 7/13, 8/4

Palatine Township:  7/27, 8/3, 8/8

Schaumburg Township:  7/13, 7/18, 7/27, 8/7, 8/8

Wheeling Township: 7/13, 7/18, 7/27, 8/3, 8/7, 8/8

 

Nightly spraying schedules can be viewed at the NWMAD website: http://www.nwmadil.com.  Alternately, a recorded phone message describing our scheduled nighttime spray program can be reached at (847) 537-2306 and pressing “5” on your telephone keypad.   More information regarding our Adulticiding program may be viewed at: http://www.nwmadil.com/Night Spray info1.html

 

 

REDUCING THE RISK OF MOSQUITO BITES:

Avoid outdoor activity if possible from dusk to dawn when the mosquitoes bite the most.  If you do go out wear light colored protective clothing and insect repellent (always read label warnings and directions).  Make sure mosquitoes do not enter homes through unscreened or broken doors or windows.   Residents are encouraged not to create mosquito harborage areas.  Make sure tall grassy areas are trimmed and other vegetation is cut back.  If plants must be watered do so in the morning so the vegetation and soil has a chance to dry making it less attractive to mosquitoes.    Empty any containers holding stagnating water like tire casings, birdbaths, flower pots and barrels that may produce mosquitoes. Un-maintained swimming pools may produce thousands of mosquitoes.  Call the District to report stagnant water areas that remain wet for more than 7 days.  Additional mosquito avoidance/control practices may be found at the District’s website: www.nwmadil.com.

 

Mike Szyska   

Director           

 

 

PLEASE FORWARD THIS INFORMATION TO APPROPRIATE DEPARTMENTS AND AGENCIES