West Nile Monitoring Report

2021 Weekly Mosquito Monitoring Report

Week of July 19, 2021

This week Forest Preserve District staff collected 2 positive West Nile virus samples. This brings the total number of positive West Nile virus samples for the 2021 season to 3. District staff began sampling for the presence of West Nile virus on June 1, 2021.

The positive samples this week were obtained from mosquitoes collected at Burlington Park in Naperville and Maple Meadows in Wood Dale. Though infected mosquitoes were collected from District traps located in these preserves, these mosquitoes may have originated from off-preserve breeding sites. Known District breeding sites that are near these positive samples are treated with a biologically derived larvicide to reduce the Culex mosquito population. Ongoing surveillance of these areas will continue in order to identify and treat all District locations that may be harboring Culex mosquito larvae.

Currently, the District is aware of 2 positive mosquito samples in DuPage County, 0 of which were found on District property this week. To date the DuPage County Health Department has reported 0 positive human cases for DuPage County. The DuPage County Health Department provides an interactive West Nile virus case map (link).

As of July 23, 2021, the Illinois Department of Public Health has reported 0 human cases, 0 human deaths, 0 positive birds, and 83 positive mosquito batches in Illinois. See the latest up-to-date IDPH mosquito surveillance data (link).


Fight the Bite

Below are some simple, common sense precautions people can take to avoid mosquito bites and protect themselves against West Nile virus:

1. Avoid being outdoors when mosquitoes are most active, especially between dusk and dawn.

2. When outdoors, wear shoes and socks, long pants and a long-sleeved shirt, and apply insect repellent that includes DEET, picaridin, oil of lemon eucalyptus or IR 3535 according to label instructions. Consult a physician before using repellents on infants.

3. Make sure doors and windows have tight-fitting screens. Repair or replace screens that have tears or other openings. Try to keep doors and windows shut, especially at night.

4. Eliminate all sources of standing water that can support mosquito breeding, including water in bird baths, ponds, flowerpots, wading pools, old tires and any other receptacles. In areas outside of Forest Preserve property, contact your municipal government to report stagnant water in roadside ditches, flooded yards and similar locations that may produce mosquitoes.

5. Public health officials believe that a hot, dry summer could increase mosquito activity and the risk of disease from West Nile virus.

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