A Douglas County mosquito sample tested positive for Saint Louis encephalitis virus, the Nevada Department of Agricutlture reported Friday.
The department’s lab found the mosquito-borne virus in specimens from Douglas and Elko counties, according to a release.
Out of 1,750 specimens tested so far this season, 42 were positive for West Nile virus. Mosquitoes carrying the disease have been found in Carson City, Churchill, Clark, Douglas, Elko, Lyon and Washoe counties.
West Nile virus established itself in this area in 2003, 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.
Unlike West Nile Virus, which was introduced into the United States in 1999 in New York and reached the Pacific coast in 2002, Saint Louis encephalitis virus has been endemic in the intermountain west for many decades.
“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.”