West Nile Virus Returns to Wyoming
By: Terry Creekmore, Wyoming Department of Health vector-borne illness prevention coordinator Source: AARP.org Date Posted: 2004-07-01 14:56:00-04:00
West Nile Virus Returns to Wyoming
By Terry Creekmore, Wyoming Department of Health's vector-borne illness prevention coordinator
West Nile virus has re-emerged in Wyoming this year. The first human case was diagnosed in Campbell County during the first week of June.
A file on my desk lists all the people in Wyoming diagnosed with West Nile virus in 2003. The list is a long one, 393 people in all.
One column lists their occupations: retired, student, coal miner, farmer, child, attorney, fire fighter… Another column simply says "F" or "E" by each entry. The Fs are those people who were diagnosed with West Nile fever, while those with an E after their name developed the brain-swelling disease, encephalitis. The next column is the worst: The heading is "Fatality" and the options are simply "yes" or "no".
There were nine yeses in Wyoming last year.
The file tells us folks in the Wyoming Department of Health all the information we need to tabulate the effects of West Nile virus (WNV) last year. But what we can't measure from this database is all of the pain, suffering and grief that those unlucky enough to be included in this file have endured.
In 1999, few people in North America had ever heard of WNV because it only existed in East Africa, the Middle East and Central Europe. Then in the late summer of that year, birds in New York City started to die from an unexplained illness. Several weeks later, people and horses joined the ranks of those stricken. Initially, WNV wasn't even considered as a cause of the outbreak because it had never occurred in the Western Hemisphere.
The 63 human cases and seven fatalities documented in New York City during the initial outbreak were big news, and as the virus spread west the numbers of human cases remained at about the same level. By 2001, WNV was identified in 27 states, with 66 human cases and nine fatalities.
But the next year everything changed when WNV was documented in 44 states and the number of human cases rocketed to 4,161. Fatalities increased from nine in 2001 to 284 in 2002. The dramatic increase in human infections continued last year when 9,388 people were stricken by WNV in the U.S. and 246 people died.
WNV was first identified in Wyoming on August 16, 2002 and spread to 15 of Wyoming's 23 counties by the end of October. Two nonfatal human cases were diagnosed in Wyoming by the end of the year. The rapid spread of the virus in Wyoming during 2002 surprised many people, but it was just a prelude to what would occur in 2003.
The file mentioned earlier is a compilation of the 393 human cases diagnosed here last year and, with nine fatalities, ranks Wyoming fifth among the 45 states reporting WNV human cases in 2003.
The age range of people infected in Wyoming last year was from 1 to 99 years, so anyone can become infected and possibly ill. However, the age range of persons who died from WNV last year was from 76- to 90-years old, with an average age of 85.5. Obviously, the chances of becoming seriously ill or dying from WNV are greater in the elderly.
The Rocky Mountain and Plains states, including Wyoming, were hard hit last year. Colorado reported more than 2,800 human cases, and Larimer County, CO led the nation with over 400 cases. The U.S Centers for Disease Control and Prevention tabulates per capita infection rates based on the number of cases per 100,000 residents. That way they can compare infection rates in New York City with those in Lingle, Wyoming.
Larimer County, which had the most human cases in the country, had a per capita infection rate of 192/100,000. In comparison, Campbell County, WY had a per capita rate of 197, Platte County had a rate of 711 and Goshen County had a per capita rate of 727. Goshen and Platte Counties in Wyoming had some of the highest infection rates in the U.S. in 2003.
The threat posed by WNV in Wyoming is real, but taking some common sense precautions can reduce the risk of infection.
First, educate yourself about the relative risk of infection in your area. Next, remove anything around your property that will hold water for more than a few days. You don't want to be growing mosquitoes in your back yard that could infect you with the disease. Also, don't spend time outdoors during dawn and dusk and after dark when mosquitoes are most active. If you have to go to the softball or soccer game at night, wear a long-sleeve shirt, long pants and use mosquito repellent with 30% DEET.
Many people in Wyoming are wondering what the human health impact of WNV will be this summer. A lot will depend on the amount of precipitation and the summer temperatures. If Wyoming is as warm and wet as last year, then the number of human WNV cases could easily equal those seen in 2003.
If this summer is substantially cooler or drier, then there may be fewer cases than were seen last year. Another point to remember is that the factors that led to increased WNV transmission in portions of Wyoming last year will continue to make those parts of the state higher risk areas in the future.
The elderly have a greater risk of becoming seriously ill from WNV, and there currently is no human vaccine to prevent infection. WNV has reemerged in Wyoming this summer, so take what precautions you can to prevent being bitten by mosquitoes.
Note: Terry Creekmore has been traveling the state talking with AARP members about how to protect themselves from contracting West Nile virus.
If you would like him to come and speak to your local group, call him at (307) 742-6638 or call Joanne Bowlby in the AARP Wyoming office at 1-866-663-3290.
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