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For Immediate Release 08/05/08

Contact: Environmental Health Supervisor Jeff Lang, 682-3636

Lane County Environmental Health began its summer mosquito testing for the West Nile virus earlier this month. The mosquito-borne virus first reached the United States in 1999 and began its march westward, reaching Oregon in 2004. Lane County has been testing mosquitoes for the virus since 2004.

West Nile virus is a disease found in birds and is transmitted to other birds and mammals via the mosquito.

The Oregon Department of Human Services reported 27 human cases of West Nile virus in Oregon last year, down from 73 cases in 2006.

Lane County found four birds infected with the virus in 2007. Now that the ongoing presence of the virus has been confirmed in Lane County, Public Health officials agree that continuing some level of surveillance efforts and taking steps toward prevention are vital in containing the virus.  Mosquito surveys will be continued in Lane County, in addition to the collection and testing of dead birds (crows and blue jays).

John Parrott, certified Master Gardener at the Oregon State University Lane County Extension Service, will conduct Lane County’s surveillance efforts by trapping and testing mosquito pools and swabbing the beaks of birds (crows and blue jays) found dead.  Surveillance began on July 21 and testing will be conducted twice weekly for the next eight weeks. The purpose of testing is to determine the prevalence of the virus in the area’s mosquito and bird populations in order to guide mosquito control and public education.

Reports of dead birds (crows and blue jays only) can be referred to John Parrott at (541) 729-8129.  Birds are only viable for testing if they have been dead for less than 24 hours and show no obvious trauma or visible signs of cause of death (i.e. killed by cat or dog, hit by car).  If the dead bird smells, has started to decompose, or is wormy, it is no longer viable for testing.  If a viable dead bird is found but cannot be reported or tested immediately, it can be double-bagged and placed in a freezer, as long as it is frozen within 24 hours of death.

In order to trap mosquitoes Parrott sets two cylindrical traps in each of three sites around the county. The traps are set in areas where birds roost because this is what attracts the mosquitoes. The three species of mosquito responsible for the majority of West Nile transmission are night-feeders. Birds and mammals are more accessible to the mosquitoes while they are still and sleeping.

The traps consist of two cylinders, one filled with dry ice and the other with a battery-operated light and fan. The mosquitoes are attracted to the CO₂ from the dry ice because it mimics a large mammal breathing. As the mosquitoes are drawn towards the CO₂ and the light they are pulled in through the fan to a small mesh bag.

Parrott collects the traps the following day and takes them to the lab. Each trap averages 500 mosquitoes, Parrott says—more mosquitoes than usual this year. In the lab Parrott sorts the mosquitoes according to species, sex and site using a microscope.

Lane County has never had a mosquito test positive for West Nile, even though we know there are positive mosquitoes because we have had birds test positive, according to Parrott.

Parrott said surveillance is an important aspect of West Nile virus prevention. Public Health officials predict that this year will be a big one for West Nile. Parrott said that personal responsibility to control West Nile is important. Below are some ways that you can limit your risk.

PREVENTION TIPS

• Look around your home and property and eliminate sources of standing water that can support mosquito breeding—for example gutters, birdbaths, and old tires.
• Because mosquitoes are most active at dawn and dusk, avoid playing or working outside at these times or wear repellent and/or clothing that covers your skin.
• When outdoors, wear long pants, long sleeve shirts and other protective clothing.
• Wear an effective insect repellant. So far, DEET has been found to work well. Follow label directions when using any repellant. However, do not apply DEET to children younger than two. Products containing oil of lemon eucalyptus provide a good alternative.
• Make sure that doors and windows have tight-fitting screens. Repair or replace screens that have tears or holes. Don’t leave doors or windows open without a screen.

For more information about West Nile virus:

• Lane County Web site: http://www.lanecounty.org/CAO_PIO/westnilevirus/wnv_main.htm 
• Oregon Department of Health Services (DHS) toll-free line 1-866-703-4636.

·        DHS Website: http://www.dhs.state.or.us/publichealth/acd/wnile/index.cfm

• CDC: http://www.cdc.gov/ncidod/dvbid/westnile/index.htm

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Amber Fossen

Public Information Officer

Lane County Government

125 E. Eighth Ave.

Eugene, Oregon 97401

(541) 682.3718

(541) 359.9143 (cell)

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