West Nile Virus Information
Idaho’s nearly 1,000 positive cases and 23 deaths from West Nile virus (WNV) in 2006 have South Central Public Health District gearing up to monitor the spread of the virus again this summer. Based on what other states have experienced, South Central Public Health District Epidemiologist Karin Frodin, R.N., predicts Idaho will have more human cases of the virus this year. 
“The large number of West Nile virus cases we experienced in 2006 was probably just the tip of the iceberg,” said Frodin. “We’ve had anecdotal reports from many people who said that they had all the symptoms but chose not to be tested last year, meaning that the nearly 1,000 confirmed cases reported in 2006 could have been just a drop in the bucket.”
The best way to protect yourself from getting West Nile virus, said Frodin, is by using personal protection measures such as wearing long sleeves and long pants, and using a mosquito repellent containing DEET, when mosquitoes are most active at dawn and dusk. Also, removing standing water from your property cuts down on the places where mosquitoes can breed, she said.
West Nile virus is transmitted to people, birds, and horses by the bite of an infected mosquito. The virus can cause serious illness in people of any age, but especially those over the age of 50 or those with other underlying medical conditions.
“Those who had West Nile virus now have long term -- possibly lifetime -- immunity to the disease,” said Frodin. “But West Nile virus is here to stay and people should be careful to protect themselves against mosquito bites and reduce mosquito breeding habitats around their homes this summer and fall.”
A new information line has been established to answer questions from the public regarding West Nile virus. It can be reached at 1-877-333-WNVI (9681). The Idaho Department of Health and Welfare also maintains a website that tracks WNV cases. See 'Fight the Bite' link above - www.westnile.idaho.gov.
2006 Statistics
In 2006, Idaho led the nation in the reports of human illness associated with West Nile virus with 996 cases being reported to the state health department. Twenty-three people died in Idaho from West Nile virus related complications in 2006; seven were residents of the south central region. Locally-acquired mosquito-borne human infections were first recorded in Idaho in 2004.
West Nile virus was discovered in five of Idaho’s seven health districts in 2006. The only districts not affected last year are located in the northern part of the state. All eight of the counties located in the South Central Public Health District experienced human, horse, and bird cases last year.
Of the 996 Idaho cases statewide in 2006, there were 825 cases of West Nile fever, a less dangerous, but still debilitating, form of the disease; 171 cases of the
neuro-invasive form of WNV, a form of the disease that can lead to encephalitis and other potentially deadly complications; 338 positive horses; and 127 positive birds.
“There is no vaccine for humans at this time and the virus is not passed from person to person. However, it may be passed through blood and transplant tissue, but those processes are strictly screened,” said Frodin. “Prevention is the best protection.”
There is a vaccine for horses and Frodin recommends that all horse owners vaccinate their horses soon.
In the south central area of Idaho, the 2006 WNV cases stacked up as follows:
County |
Human Cases WNV Fever |
Human Cases WNV Neuro-invasive |
Horses |
Birds |
Blaine |
9 |
1 |
4 |
1 |
Camas |
1 |
1 |
1 |
0 |
Cassia |
1 |
3 |
10 |
1 |
Gooding |
40 |
6 |
2 |
7 |
Jerome |
10 |
2 |
3 |
7 |
Lincoln |
7 |
2 |
5 |
1 |
Minidoka |
16 |
8 |
8 |
2 |
Twin Falls |
29 |
10 |
22 |
11 |
Symptoms
Most human infections of West Nile virus are mild or have no symptoms. Approximately 20 percent of those infected develop West Nile fever, a generally mild fever that lasts from 3 to 6 days and begins from 3 to 14 days after infection. Symptoms often include fever and headache, muscle aches, tiredness, nausea and vomiting, eye pain, skin rash, and enlarged lymph nodes.
Less than one percent of people infected develop the serious neurological disease called West Nile encephalitis. Blood tests to confirm the disease are available through commercial laboratories. Those over age 50 are more susceptible to serious complications from the virus.
The Idaho State Laboratory will limit their testing to more severe forms of the disease including encephalitis or hospitalized cases. People with mild fevers and flu-like symptoms are encouraged to consult their physician to discuss the necessity of testing.
Surveillance Measures
Frodin said that South Central Public Health District will not be setting mosquito traps this year. Since the virus is now considered endemic to our area, the best advice she can give to people is to assume that you can catch the virus wherever mosquitoes are present and use personal protection measures such as applying a mosquito repellent containing DEET, wearing long sleeves and long pants at dawn and dusk, and keeping your property free of standing water where mosquitoes can breed.
Frodin also announced that the Idaho Department of Fish and Game will continue collecting dead birds that may have died from West Nile virus. Idaho tests dead magpies, crows, jays, and raptors, such as red tail hawks. West Nile virus has a high mortality rate among these birds. All dead birds to be tested and calls concerning dead birds should go directly to the local Fish and Game office in Jerome at 324-4359.
Prevention Measures
Frodin advises people to insect proof their homes and reduce standing water on their property that might provide breeding habitat for mosquitoes. Other tips include:
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Cover up exposed skin when outdoors. Wear long sleeves, light-colored, and loose-fitting clothes.
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Apply insect repellent containing DEET to exposed skin and clothing. Follow instructions on the product label, especially for children.
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Avoid mosquitoes when they are most active at dawn and dusk.
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Empty birdbaths and clean decorative ponds every three to six days. It is also important to eliminate mosquito-breeding areas such as clogged rain gutters, old tires, and other items that contain standing water.
Publications |
2007 TV Spots |
For More Idaho West Nile Virus Information
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1(877)333-WNV1 {9681}