More West Nile Virus cases discovered in western Nevada

The Nevada Department of Agriculture’s Animal Disease and Food Safety Laboratory has detected additional cases of West Nile Virus in Northern Nevada.

After detection of West Nile Virus positive mosquito pools in Douglas County earlier this month, the presence of infected mosquitoes, and therefore the potential for viral transmission to humans and animals, has been confirmed in Washoe County, Carson City and Mason Valley.

Climate conditions have been conducive for arbo-viral (arthropod-borne) transmission for weeks in the northern part of the state. West Nile Virus established itself in this area in 2004, and detection of viral transmission either in positive mosquito pools, birds or horses usually starts in mid- to late-July in Northern Nevada. Mosquito season in this area usually ends with the first killing frosts in October.

“All horse owners should update their animal’s West Nile Virus vaccination,” said Dr. Annette Rink, acting state veterinarian and supervisor of the Animal Disease and Food Safety Laboratory.

Four effective vaccines exist for horses, but vaccine development for humans is still under way with currently no available product in sight.

“Nevada has had cases of West Nile Virus since 2003,” Rink said. “This should serve as a reminder, especially to people 50 years and older, to use repellent containing DEET and to wear long sleeves, pants and socks when outside, especially during dawn and dusk. Also, remove any standing water from around your house and check to make sure your window screens fit properly.”

CDC evaluation of information contained in peer-reviewed scientific literature, and data available from the Environmental Protection Agency (EPA), have identified several EPA registered products that provide repellent activity sufficient to help people avoid the bites of disease carrying mosquitoes. Products containing these active ingredients typically provide reasonably long-lasting protection:

DEET (Chemical Name: N,N-diethyl-m-toluamide or N,N-diethly-3-methyl-benzamide)

Picaridin (KBR 3023, Chemical Name: 2-(2-hydroxyethyl)-1-piperidinecarboxylic acid 1-methylpropyl ester )

Oil of Lemon Eucalyptus* or PMD (Chemical Name: para-Menthane-3,8-diol) the synthesized version of oil of lemon eucalyptus

IR3535 (Chemical Name: 3-[N-Butyl-N-acetyl]-aminopropionic acid, ethyl ester)

EPA characterizes the active ingredients DEET and Picaridin as “conventional repellents” and Oil of Lemon Eucalyptus, PMD, and IR3535 as “biopesticide repellents”, which are derived from natural materials. For more information on repellent active ingredients, please visit: http://www.epa.gov/pesticides/health/mosquitoes/ai_insectrp.htm.