Currently, control efforts have been directed towards larviciding due to the 2.5”-3.6” rains that hit most of northern Cook County. The insect growth regulator methoprene (Altosid) will be primarily used in most areas with Bacillus sphaericus (Vectolex) in other areas. Crews have detected a hatch of the floodwater mosquito (Aedes vexans). The magnitude of this floodwater mosquito hatch will be dependent on additional rains. 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. Floodwater mosquitoes are likely to make their presence known by the end of next week or the last week of August depending on temperatures.

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. This problem will now be compounded due to the recent rains. 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 already completed spraying of the entire NWMAD District once 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 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

Five human cases of WNV have been reported in Illinois according to the Illinois Department of Public Health. More human cases are expected. Three of the cases were from Cook County, One from Will and the other from Madison. Human cases are starting to show up in numerous states and the CDC expects to see a sharp increase in new cases. Four of the cases developed in to the more serious West Nile encephalitis and one resulted in the less severe West Nile Fever.

HORSE CASES OF WNV

Thirteen horses have been reported positive for WNV. Horses were from the counties of: Coles, Jackson, Kankakee, Madison, McDonough, Sangamon & Williamson.

MOSQUITO VIRUS SURVEILLANCE IN ILLINOIS

NWMAD has tested 278 Culex mosquito batches to date for West Nile Virus (WNV) and St. Louis encephalitis (SLE) using the VecTest. Fifty-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 353 birds have tested positive for WNV in 77 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.

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.

WNV AND PETS

Numerous residents have inquired about the risks of their pets becoming infected with WNV. Although pets may be bitten by WNV infected mosquitoes there have been no significant reports of illness or deaths in cats and dogs due to WNV in the states out East. This information would suggest that most dogs and cats are less sensitive to the virus. Dog & cat owners may still wish to protect their pets from infected mosquitoes by limiting their nighttime activity if possible. Using repellents on pets is not recommended because of their grooming behavior. Owners should consult a veterinarian regarding any other methods of protection. Birds can be very sensitive to WNV and they should, if possible, be kept in a mosquito free environment. Birds found infected (but not necessarily seriously) with WNV include: chicken, cockatiel, cockatoo, macaw, parakeet, peacock, goose and turkey. Raptors such as hawks, eagles, and owls can be very sensitive to the virus resulting in fatalities.

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 5 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

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