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DHS news release

Aug. 8, 2006

General contact: Bonnie Widerburg, 971-673-1282


Technical contacts: Chris Thomas, Malheur County Health Dept., 541-889-7279
Brian Wickert, Malheur County Environmental Health, 541-473-5564
Emilio DeBess, Oregon Dept. of Human Services, 971-673-1111


Public health officials confirm three West Nile virus cases

The Oregon State Public Health Laboratory has confirmed that three people in Malheur County have tested positive for West Nile virus infection, public health officials at the Oregon Department of Human Services Public Health Division said today.

They are the year's first human WNV cases in the state. Oregon recorded eight human cases in 2005 and five cases in 2004.

"All three of these people are recovering," said Chris Thomas, public health nurse in Malheur County. "This is the time of year when we would expect to start seeing the appearance of West Nile virus, and it's a definite reminder for people to start taking personal precautions against mosquito bites."

"Oregon has been experiencing a heat wave with temperatures in some areas consistently above 100 degrees, which is conducive to mosquito breeding and virus replication." said Emilio DeBess, D.V.M., epidemiologist in DHS. "As a result, we expect a rapid rise in mosquito activity over the next few weeks. Oregonians need to step up their efforts to protect themselves from mosquito bites when outside, especially those individuals who work outdoors."

Also today, Oregon State University's Veterinary Diagnostic laboratory confirmed a positive WNV bird in Jordan Valley in Malheur County, DeBess said.

DeBess recommends five key actions people can take to protect themselves:

  • Screen doors and windows should fit tightly. Repair or replace screens that have tears or holes.
  • Wear long pants, long-sleeve shirts and other protective clothing when outside.
  • Eliminate all sources of standing water that can support mosquito breeding such as clogged gutters, birdbaths and old tires.
  • Avoid playing or working outside at dawn and dusk, when mosquitoes are most active.
  • Use an insect repellant, preferably one that contains DEET, Picaridin or oil of lemon eucalyptus. Follow label directions carefully. Never apply DEET directly to children or put it on children's hands. Apply repellant first to your own hands and then onto the child. Do not use oil of lemon eucalyptus on children under age three.

DeBess said CDC-reviewed research suggests that repellants containing DEET or Picaridin typically provide longer-lasting protection than other products and that oil of lemon eucalyptus providers longer-lasting protection than other plant-based repellants.

He said a product containing 23.8 percent DEET provided an average of five hours of protection from mosquito bites; a product containing 20 percent DEET almost four hours of protection; a product with 6.65 percent DEET almost two hours and those with 4.75 percent DEET roughly 90 minutes' protection.

DeBess said that people infected with West Nile virus usually have no illness or only mild symptoms. "About 20 percent of cases result in a flu-like illness. In one out of 150 cases, the virus can cause inflammation of the brain and result in serious illness or even death. This most commonly occurs in persons 50 years or older," he said.

West Nile virus normally lives in birds. It is spread when a mosquito feeds on an infected bird and then bites a human. Birds cannot transmit the disease to humans, nor can it be transmitted through person-to-person contact, according to DeBess.

So far this year, West Nile has been detected in three Malheur birds, two horses in Malheur and Harney Counties and in four Baker County mosquito pools. In 2005, Oregon recorded the infection in 8 humans, 14 birds and 41 horses.