Most of the District received an additional 4-6 inches of rain on August 21^st. The floodwater mosquito Aedes vexans has already been reported as biting in Hanover and Barrington townships. The current brood was produced from 2.5-3.5 inch rains from August 14^th. It is expected that the excessive rains on the 21^st will produce a significant brood of floodwater mosquitoes just before the Labor Day holiday. Floodwater mosquito annoyance may add to the public’s fears regarding West Nile Virus (WNV) since they more readily bite humans both day and night. Currently, research has not implicated the floodwater mosquito Aedes vexans as a vector of WNV.

Culex mosquitoes remain a consistent problem due to the additional rains opening up new production sites. Larviciding efforts with the insect growth regulator methoprene and the microbial Bacillus sphericus have been directed at both the Culex and floodwater mosquitoes.

Homeowners should be strongly urged to remove any stagnating water on their property that may produce these mosquitoes. Culex mosquito numbers increase this time of the season. Virtually any water container (i.e. flower pots, garbage cans, pails, bird baths, un-maintained swimming pools, catch basins, etc) containing organic debris like leaves or grass can produce hundreds of these mosquitoes in about a week’s time during warm temperatures. Homeowners should also avoid watering lawns near open ditches or low areas that may cause water to accumulate in culverts under roadways.

ADULT MOSQUITO SPRAYING

Crews have nearly completed spraying of the entire NWMAD District twice and up to 4 times in areas that we detected multiple WNV infected mosquito batches, dead birds and high Culex mosquito numbers in our traps. Now infected mosquitoes have been detected in most all areas of the District. Weather permitting our night spraying for adult mosquitoes will be continuing this week and next week based on our surveillance efforts. This is necessary to help reduce the number of Culex mosquitoes already infected with WNV. Nightly spray schedules are available at our website www.nwmadil.com and updated by 3 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

Sixty one human cases of WNV have been reported in Illinois according to the Illinois Department of Public Health. More human cases are expected. Human cases in Illinois include: Cook (33), Chicago (10), DuPage (4), Ford (1), Jackson (1), Madison (2), Montgomery (1), Sangamon (2), Shelby (1), St. Clair (1) and Will (5). Human cases are starting to show up in numerous states and the CDC expects to see a sharp increase in new cases. Currently, there have been 4 deaths reported from WNV in Illinois from Westmont, Bridgeview, Chicago and Morton Grove.

NOTE: Despite the tragedy of 4 deaths from WNV, which would still be considered low for a population the size of Chicagoland, it is also important to appreciate the non-fatal and potential long term affects this disease may impart to its victims. According to Drs. Petersen & Marfin in a recent article in the Annals of Internal Medicine (2002; 137;173-179), although few data exists regarding longer term complications from WNV, studies performed in New York and New Jersey in 2000 suggest that patients hospitalized for WNV may exhibit long term morbidity from the illness. Among those requiring hospitalization for WNV more than half did not return to their functional level by discharge time and only a third were fully ambulatory. New York patients 1 year after recovery from WNV reported persistent symptoms including: fatigue, memory loss, difficulty walking, muscle weakness, and depression.

MOSQUITO VIRUS SURVEILLANCE IN ILLINOIS

NWMAD has tested 289 Culex mosquito batches to date for West Nile Virus (WNV) and St. Louis encephalitis (SLE) using the VecTest. Sixty-four mosquito batches have tested positive for WNV so far. Mosquitoes testing positive in the District are posted on the NWMAD website www.nwmadil.com.

DEAD BIRD SURVIELLANCE INFORMATION:

As of this writing 439 birds have tested positive for WNV in 92 counties in Illinois according to the Illinois Department of Public Health. 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.

ILLINOIS DEPARTMENT OF AGRICULTURE EMERGENCY LARVICIDING EXEMPTION TREATMENTS

The IL. Department of Agriculture granted an emergency rule to allow unlicensed application of three mosquito larvicide formulations following a minimum of 1 hr. of training by a licensed mosquito control applicator. Larvicide applications are allowed with Summit B.T.I. Briquets (USEPA Reg. #6218-47), Zoecon Altosid Briquets (USEPA Reg. # 2724-375). Zoecon Altosid XR Extended Residual Briquets (USEPA Reg. # 2724-421).

In effort to avoid duplication of larviciding efforts NWMAD is recommending that those licensed or trained city/village personnel that intend to do larviciding concentrate their efforts on the following Culex mosquito production sites:

1.) Catch basins other than street basins since they have already been treated by NWMAD. Example basins would be those found in residential backyards or on out-of-the-way easements.

2.) Backyard ornamental ponds and low areas that: do not have fish, are not aerated and will stagnate for 7 days or longer.

3.) Any container with organic/plant material in it that holds water for 7 days or longer. Example containers would be tire casings, flower pots, clogged rain gutters, stagnant bird baths, uncovered boats, pails, drums, etc.

4.) Un-maintained swimming/wading pools that are un-chlorinated and with organic matter in them that hold water for 7 days or longer. Remember even sagging pool covers if not dumped out weekly may produce Culex mosquitoes. Drain such sites weekly if possible.

5.) New building foundations (w/basements) that are flooded with inoperative sump pumps may be intense Culex mosquito production sites. Additionally, abandoned buildings or those bound for demolition may also be mosquito production sites. Those cities & villages that have forwarded the location of these properties to us have already been treated.

If cities/villages cannot perform these treatments please call our District and report new mosquito production sites or check whether a water site has been previously treated. Because of heavy telephone traffic call (847) 537-2306 and select phone option “3” under “new water site reporting”. Alternately, you can email these reports/inquiries to our Chief of Field Operations (FO@nwmadil.com).

DEAD BIRD DISPOSAL

The state and county are no longer testing birds in NW Cook County so homeowners are now recommended to dispose of dead birds on their property. The safest method would be to double bag the dead birds without touching them and dispose of them in their outside garbage receptacles. Residents can expect to see a dramatic increase in the number of dead birds.

Local health authorities have also reported higher than average dead birds located near bird feeding areas. Residents are advised to discontinue wild bird feeding since this activity increases the likelihood of bringing WNV infected birds into your area and possibly infecting mosquitoes locally. Large numbers of birds in such confined areas may also increase the risk of bird-to-bird transmission of the virus that has been demonstrated in laboratory studies done by the USGS. It is not know for certain to what extent bird-to-bird transmission is significant in nature at this time but we do know that if you feed them you will probably have to dispose of more dead birds from your property.

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, bird baths, flower pots 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