SHERIDAN — One case of West Nile Virus was reported to the Wyoming Department of Health involving an adult from Campbell County. To prevent cases in Sheridan, entities are treating water drainage areas in Sheridan County.
The first case, reported in mid-June, was earlier than normal. Kim Deti, Wyoming Department of Health public information officer, said WNV is normally reported in Wyoming in late July. WNV can lead to extreme illness and possibly death. The worst year of WNV in Wyoming was 2003 when 393 cases and nine deaths were reported. In 2018 there were four reported cases and one death.
WNV is transmitted by mosquitoes. A mosquito will bite a bird with WNV and then bite a person, passing the virus on to that person.
To help prevent WNV from spreading, Sheridan County Weed and Pest is treating major water drainages in the county. They treat for mosquitoes when they are still in the larva stage using natural soil bacteria called Vectobac 12 AS, a form of biological control. This bacteria occurs naturally in the soil and is not harmful to humans livestock, fish or other wildlife said Luke Sander, Sheridan County Weed and Pest supervisor.
The bacteria is spread 100 feet on each side of any standing water that Sheridan County Weed and Pest identified as an area where mosquitoes are breeding, Sander said.
Mosquito larva seek out the bacteria to eat. Once ingested, it will crystallize in the stomach, preventing them from becoming adult mosquitoes, thus preventing the spread of WNV, said Amber Marosok, Sheridan County Weed and Pest special project manager.
To check areas needing to be treated, Marosok said staff collects larva samples from drainage areas. If the population breaks a threshold, then treatment is applied the next week. Normally treatment is done the second full weeks of June, July and August. Airplanes treat the areas by flying over designated areas and spraying bacteria over them. Air application services are contracted out to Bighorn Airways, Marosok said.
The main species of mosquito being targeted is the Culex Tarsalis, the species that spreads WNV in Wyoming. Staff cannot remove all larvae, but the goal is to reduce the population as much as possible.
There are precautions everyone can take to help prevent WNV.
Sander said the using bug spray that has DEET and avoiding spending time outside during dawn and dusk can help avoid mosquito bites, as the mosquitoes are more active during dawn and dusk.
Wear clothing made out of tightly-woven fabrics that cover skin. Drain any stagnant water. Mosquitoes only need a half a cup of water to reproduce, Sander said.
Sheridan County residents can buy products from Sheridan County Weed and Pest for individual application and treatments. Vectobac 12 AS is safe to use around other plants and animals and is approved for organic farming.
The wet spring resulted in increased standing water and thus more breeding grounds for mosquitoes.
There are different effects of WNV on a person. Not every one that falls ill with WNV will show symptoms or contract an illness. This makes it difficult to accurately record cases each year, Deti said.
Others become ill and have these symptoms including fever, headache, body aches, skin rash and swollen lymph nodes.
A small percentage of people will get West Nile neuroinvasive disease. Symptoms include severe headache, fever, neck stiffness, stupor, disorientation, coma, tremors, convulsions and paralysis. To treat this, hospitalization is usually required. The outcome can be deadly; the most recent death in Wyoming happened last year. There is not a cure for WNV, but hospitalization may help fight the disease and prevent death.
West Nile is preventable and is still active in Wyoming, with a few reported cases of WNV every year, Deti said.