NORTHWEST MOSQUITO ABATEMENT DISTRICT

147 W. Hintz Rd.

Wheeling, IL. 60090

Phone: (847) 537-2306

Fax: (847) 537-2583

www.nwmadil.com

 

Mosquito Update

July 26, 2007

 

WEST NILE VIRUS PRECAUTIONS URGED!

Flavivirus outbreaks like WNV typically occur during hot-dry summers.  2007 periodic rainfall appears to slow WNV activity as it did similarly in 2004 during May-August.  2004 also had record low August temperatures to help suppress mosquito activity. Although it may be counter-intuitive to think that rainfall would slow mosquito production; it does also flush-out typical stagnant water habitats favored by the developing larvae thus helping reduce Culex populations.  If WNV does indeed follow a similar 2004 trend, substantial virus amplification in the District will be starting now and should become evident in mosquito virus testing during the end of July or 1st week of August!  If we now begin to move into hot-dry conditions that will greatly accelerate the number of infected mosquitoes and the risk of human infections.

 

DIRECTOR’S NOTE: 

WNV is entering the amplification stage whereby infected mosquitoes and birds, if consistent with other WNV years, will increase very rapidly.  The risk of human infection will also increase as the likelihood of an opportunistic, infected, blood feeding mosquito feeding on a human also increases.  IT IS THEREFORE PARAMOUNT THAT RESIDENTS PROTECT THEMSELVES FROM MOSQUITO BITES AT THIS TIME AND THROUGH THE MONTH OF SEPTEMBER!  CITIES, VILLAGES AND MUNICIPALITIES SHOULD ALSO WARN RESIDENTS OF THIS INCREASING RISK!

 

PRESENT CONTROL STATUS:

NUISANCE MOSQUITO CONTROL

Nuisance mosquito (Aedes vexans) numbers peaked July 17th- 18th averaging 43 in New Jersey light traps.   Control efforts and minimal localized rainfall moderated their numbers significantly. Since then nuisance numbers have decreased.  Interestingly, rainfall periodicity and temperatures up to this point in time were similar in 2004 and nuisance mosquitoes then peaked on July 14th averaging around 62 in our traps and then decreased just as quickly as they did now in 2007.   Additional significant rainfall amounts could change this trend! 

 

CULEX MOSQUITOES

Culex mosquito numbers will continue to increase if warmer temperatures prevail.  Elevated temperatures accelerate Culex development in stagnant water areas as well as the risk for WNV.   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/or the insect growth regulator methoprene (a.k.a. Altosid).  A second round of street catch basin treatments has begun.  Catch basins are treated with a 150-Day methoprene formulation.

 

MOSQUITO VIRUS SURVEILLANCE IN ILLINOIS

NWMAD has tested (VecTest/PCR) 449 batches of mosquitoes for West Nile Virus, St. Louis and Western Equine encephalitis.   Fourteen WNV infected batches of mosquitoes have been collected in NWMAD gravid traps to date.  In 2004 by this same time period we had 6 infected mosquito batches in our District!   This trend is also consistent with the Illinois Department of Public Health’s low WNV activity reported throughout the state of Illinois.

 

The Illinois Department of Public Health (IDPH) reports:  7 counties with mosquitoes or birds testing positive for WNV.  There are 3 human cases (1-Cook County (Evanston)) of WNV and 90 WNV positive mosquito samples reported from Illinois.  In 2004 IDPH reported 40 counties with WNV activity by July 26th.

 

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

 

ADULTICIDING (Night Spraying Operation):

Targeted, focal adulticiding will likely be scheduled if amplification of WNV is evident in gravid trap collected mosquito batches.   This will be necessary to kill already infected Culex mosquitoes likely to infect more birds and possibly humans. 

 

Nightly spraying schedules can be viewed at the following website: http://www.nwmadil.com/nitespry_map.html.  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.