NORTHWEST MOSQUITO ABATEMENT DISTRICT

147 W. Hintz Rd.

Wheeling, IL. 60090

Phone: (847) 537-2306

Fax: (847) 537-2583

www.nwmadil.com

Mosquito Update

September 29, 2004

PRESENT CONTROL STATUS:

NUISANCE MOSQUITOES:

Nuisance mosquitoes (Aedes vexans) are low in the single digits from light traps. This trend is expected to continue since no significant rains have occurred and crews have treated priority floodwater sites with insect growth regulator residuals.

CULEX MOSQUITOES:

Cooler temperatures have reduced Culex mosquito numbers in the District. Larviciding efforts with the insect growth regulator methoprene and the microbial Bacillus sphericus have been directed at these mosquitoes. Current Culex mosquito numbers and continued detection of WNV infected mosquito batches still indicate a risk of human infection. Residents still NEED to practice MOSQUITO AVOIDANCE outdoors where mosquitoes are biting. Mosquito repellents should still be used if residents are expected to be outdoors during mosquito biting times!

ADULT MOSQUITO SPRAYING

Due to cool evening temperatures all nightly mosquito spraying has been suspended. The cooler temperatures reduce mosquito activity in the evenings decreasing the effectiveness of this control method. If nightly temperatures during peak mosquito activity periods return to 60 degrees or higher and virus continues to be detected in mosquitoes nightly spraying may be restarted.

NOTE: Even though the cooler temperatures reduce mosquito activity residents are still advised to take proper precautions to avoiding mosquito biting. While less active, mosquitoes may still bite if their resting areas are disturbed. Also be aware that some mosquitoes may enter houses attracted to the warmth they provide or with normal in/out house traffic.

Nightly spray schedules are available at our website www.nwmadil.com and updated by 2 PM each day. Alternately, residents can call us at (847) 537-2306 and listen to a schedule by selecting phone option “5” when they hear the recorded message.

HUMAN CASES OF WNV

Four human cases of WNV have been reported in the NWMAD territory according to the Illinois Department of Public Health. Thus far 40 human cases have been reported in Illinois by the Illinois Department of Public Health. It is likely that more human cases will be reported throughout Illinois during the next few months due to the length of time it takes to confirm the illness in people. At the end of September 2003, nine human cases were reported; for 2004 there are twelve human cases in Cook County.

MOSQUITO VIRUS SURVEILLANCE IN ILLINOIS

NWMAD has tested 771 Culex mosquito batches to date for West Nile Virus (WNV), St. Louis encephalitis (SLE) and Eastern Equine encephalitis (EEE) using the VecTest. 250 mosquito batches have tested positive for WNV so far. The number of Culex mosquitoes testing positive for WNV in the NWMAD territory, thus far, in 2004 is 2.7 times higher than the number of mosquitoes testing positive for WNV, this same time, in 2003 (n=771, n=959, respectively)! Mosquitoes testing positive in the District are posted on the NWMAD website http://www.nwmadil.com/VECTEST1.htm

NOTE: Cooler temperatures will reduce mosquito activity. Normally, when daylight hours decrease this time of the year Culex mosquitoes will begin to enter a diapause state in preparation for overwintering. Unlike, nuisance floodwater mosquitoes that lay their eggs in the soil and then the adults die out with the first hard frost, Culex spend the winter in protected areas as adults and then become active again during the first warm days of spring. When Culex enter diapause they stop blood feeding, however, it may take considerable time for the entire population to enter this diapause state. Therefore it is still possible that some mosquitoes may yet be blood feeding and infect a human being or bird. Mosquito bite avoidance is still very advisable.

DEAD BIRD SURVIELLANCE INFORMATION:

As of this writing 595 dead birds have been reported to our website. NWMAD dead bird report website can be accessed at: http://www.nwmadil.com/Dead Birds.html Current information about WNV can be found on the state’s website www.idph.state.il.us/envhealth/wnv.htm or by calling 217-782-5830.

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, loose fitting, 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 unnecessary 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 for 7 days or longer like: tire casings, birdbaths, flowerpots and barrels that may produce mosquitoes. Neglected swimming pools may produce thousands of mosquitoes. Call the District to report large stagnant water areas that remain wet for more than 7 days.

Mike Szyska

Director

PLEASE FORWARD THIS INFORMATION TO APPROPRIATE DEPARTMENTS AND AGENCIES