The Wyoming Department of Health (WDH) is asking Wyomingites to exercise caution amid an increase in cases of the West Nile Virus. So far, there have been 21 confirmed cases across nine counties this year, with one resulting in the death of an older Fremont County woman. Cases have been detected in Campbell, Fremont, Goshen, Laramie, Natrona, Park, Platte, Sheridan and Washakie counties. Mosquito pools and animals from around the state also continue to test positive for the virus.
“There's lots of factors that go into the increase. I think one of the driving factors this year is all of the moisture that we've had, so a lot of snow through the winter that melted off, and then we've had kind of a wet spring in summer, which has created cooled waters where mosquitoes like to breed,” said Courtney Tillman, an epidemiologist with the WDH.
The uptick this year is more than what’s been experienced in the last decade or so. Of these 21 cases, 12 have been the neuroinvasive strain of West Nile, a more serious form of the virus that can include symptoms such as severe headache, fever, neck stiffness, stupor, disorientation, coma, tremors, convulsions and paralysis. However, health officials stress that most people that contract the virus don’t experience symptoms, and for those that do, they may experience less severe reactions like skin rashes or diarrhea. More serious cases often occur in adults aged 60 and older. Additionally, those who are immunocompromised can be more susceptible to the virus.
“As far as younger goes, we don't necessarily see a difference in who experiences symptoms and who doesn't for the more mild illness. So really anyone that gets bitten by one of these mosquitoes, if that mosquito’s infected, you have a chance of developing symptoms if you get West Nile,” Tillman said.
Even with the days getting shorter and temperatures getting cooler, the WDH cautions that West Nile Virus season isn’t over yet with cases likely to continue on-pace with what they’ve been earlier this year.
“Looking at previous years’ data, we know that we get the most human cases during August and September, so we do expect that we will see more cases through at least the end of the month, potentially longer depending on the weather,” she said. “Hopefully, we get a bit of freeze soon, which helps kill off some of those mosquitoes.”
The WDH recommends taking precautionary measures to reduce the chances of getting West Nile Virus. They include avoiding spending time outside during dawn and dusk when mosquitos are most active, wearing long pants and long-sleeved shirts when outdoors, applying an insect repellent that contains DEET, Picaridin, or oil of lemon eucalyptus and draining or reducing standing water that serves as mosquito breeding grounds – like in old tires or bird baths. Using screens if windows are opened can prevent mosquitoes from coming indoors. Tillman added that those who work or spend extended periods of time outside can use permethrin on their clothing, a scentless chemical which helps to repel mosquitos and can last on clothing through several washes.
West Nile Virus is spread by mosquitoes when they feed on infected birds and then bite people, animals or other birds. Reported annual human cases have ranged from one last year to 393 in 2003.
Certain birds such as crows, ravens, jays, raptors, owls and sage grouse are particularly susceptible to West Nile Virus. Questions and concerns about wild birds should be directed to a local Wyoming Game and Fish Office or by calling (307) 745-5865.
