Mosquito-borne encephalitis season returns

Health Department offers tips to families on protection from mosquito-borne illnesses

The warmer weather of spring and spring rain mean Winnebago County residents should start noticing increased mosquito activity in their community. It is too early to know what amount of West Nile virus (WNV) or St. Louis encephalitis (SLE) activity we will have in our community this season.

Above-normal temperatures appear to increase the rate of Culex mosquito production, mosquito flight activity and virus replication, thereby increasing the proportion of birds and mosquitoes infected with WNV or SLE and the risk of disease to humans.

West Nile virus and St. Louis encephalitis are both transmitted to humans from the bite of a mosquito that has picked up the virus by feeding on an infected bird. In the summer of 2004, Winnebago County reported no human cases of both diseases and had over 1,200 dead crows reported and more than a 1 dozen mosquito pools infected with WNV.

Based on nationwide experience over the previous five years of WNV presence in the United States, the peak period for WNV transmission, particularly to humans, has been from the last week of August through the middle of September. It is important to keep in mind again that this is influenced by many environmental factors that affect the viral amplification cycle (e.g., weather, host and vector densities, immune status and other characteristics).

“Once again, the Winnebago County Health Department has opened a phone line for residents to report the location and number of dead crows or blue jays,” said Larry Swacina, Environmental Health director. The report line number to call is (815) 720-4245. “After calling in a report of a dead bird, please dispose of the bird yourself,” Swacina added.

When calling the hotline to report dead crows or blue jays, please leave the address, ZIP code, town and number of dead birds found. The Illinois Department of Public Health has limited the number of crows that can be submitted for WNV testing in 2005.

Remember, dead birds cannot spread West Nile virus, but it is advised to avoid barehanded contact with dead birds and other animals since they carry a variety of germs. Please use a shovel, gloves or double-plastic bags to place the carcass in garbage bag or can,” added Swacina. The Health Department has also opened a West Nile virus Information line for residents who have questions or wish to speak to a health professional. That number is 720-4240.

The best protection against mosquito-borne encephalitis is to limit activities at dawn and dusk, when mosquitoes that could carry the virus are most active. Protective clothing will ideally include lightweight, loose fitting, long-sleeved shirts, pants and socks. It’s best to always apply a repellant containing DEET (25% for adults, 10% for children, and not recommended for infants) when going outdoors. New this year, CDC has added two new products containing picaridin and lemon of eucalyptus. Both new ingredients have also proven effective as mosquito repellents.

Most people infected with West Nile Virus or St. Louis encephalitis have no signs or symptoms of illness. Some individuals may become ill, usually three to fifteen days after having been bitten by an infected mosquito. The virus may occasionally cause serious complications. In some individuals, particularly the elderly, the virus can cause muscle weakness, inflammation of the brain (encephalitis), stiff neck, stupor, disorientation, tremors, convulsions, paralysis, coma or death. It should be noted that the odds of being bitten by an infected mosquito and developing serious or life-threatening symptoms are minimal. Nevertheless, taking all recommended precautions (below) is encouraged, due to the potential seriousness of becoming infected by West Nile Virus or St. Louis encephalitis.

Personal/Home Precautions to Prevent Mosquito Borne Encephalitis:

Alert health authorities to potential mosquito breeding sites in your area.

Avoid outdoor activities in the early morning and at dusk. Whenever outdoors between dusk and dawn, wear shoes and socks, long pants and a long-sleeved shirt. Loose-fitting, light-colored clothing is best.

Apply insect repellent to exposed skin. An effective repellent will contain 25 to 35 percent of the active ingredient DEET or picaridin or lemon of eucalyptus. Spray the repellent not only on exposed skin but also on clothing. Consult a physician before using repellents on very young children.

Drain standing water in your yard at least once a week. Pour water from mosquito breeding sites, such as flower pots, pet bowls, clogged rain gutters, swimming pool covers, boats, discarded tires, buckets, barrels, cans, or similar items in which mosquitoes can lay eggs. For permanent standing pools of water, mosquito larvicide can be used. The larvicide can be purchased from many retail stores selling garden supplies. Please follow the manufacturer’s recommendations for use.

Check screens on porches and patios for tears and other openings.

In 2004, the Winnebago County Health Department produced a six minute video on West Nile virus called “Fight the Bite.” “The video is not only entertaining but educational to inform Winnebago County residents how to protect themselves from the West Nile virus” said Sue Fuller, community relations manager. “The star in the video is Niles, the rambunctious mosquito who keeps the audience entertained with his pesky antics” added Fuller. George Blomgren, Winnebago County’s first West Nile Virus case tells his compelling story on his battle with West Nile virus and why he participated in the making of the video. The video is currently in video Outlet stores in Winnebago County as a free rental.

For more information on West Nile virus, visit the following Web sites:

Illinois Department of Public Health at

Center for Disease Control at

Winnebago County Health Department at

From the June 15-21, 2005, issue

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