With the number of birds and mosquitoes infected with West Nile virus rising, the Sacramento-Yolo Mosquito & Vector Control District has scheduled aerial spraying of a low-toxicity insecticide over Davis and Woodland this week.
The spraying will take place on Wednesday and Thursday between 8 p.m. and midnight, around the time mosquitoes are most active.
“Once we know the adults are infected and flying, aerial spraying is the only way to reduce them significantly and quickly,” said Luz Rodriguez, the district’s spokeswoman.
The insecticide Trumpet will be dispersed at ultra-low volumes over the cities. It poses minimal risk to humans and the environment, and people do not need to stay inside or close their windows, Rodriguez said.
The district has treated hot spots in and around Davis and Woodland with ground applications, she said, but a steady increase in the number of infected mosquitoes prompted more serious measures.
“Every season is different; this just seems to be a very intense year statewide,” Rodriguez said.
One possible reason for the increase is that drought conditions have results in more naturally occurring standing bodies of water than other years. Mosquitoes and birds then congregate at the available water, and transmission rates can increase.
There have been no confirmed human cases of West Nile virus in Yolo or Sacramento counties, but the state has seen 19 — already five more than in all of 2013.
West Nile virus is spread by mosquitoes. Many people infected with the virus don’t experience any signs or symptoms, or may experience only minor ones, such as fever or mild headache. However, some people who become infected develop a life-threatening illness that includes inflammation of the brain.
While no human cases have been reported in Yolo, the disease is certainly present, district officials said. A total of 132 mosquito samples, 26 dead birds and one sentinel chicken have tested positive for West Nile to date.
Residents are encouraged to remove any standing bodies of water from their back yards, protect against mosquito bites with repellent and by wearing pants and long sleeves, and report suspected residential mosquito breeding grounds. Residents can sign up for spraying alerts in their areas by going to www.fightthebite.net/spray-notification/.
Aerial spraying will take place over two areas. The Davis block is approximately 20,000 acres bounded by County Road 29 on the north down to Levee road on the south, and from County Road 98 on the west to County Road 105 on the east.
The Woodland block is about 12,000 acres from Churchill Downs Avenue on the north to County Road 25A on the south and from County Road 97 on the west to County Road 102 on the east.
For exact spraying locations, visit www.FIGHTtheBITE.net.
— Reach Elizabeth Case at firstname.lastname@example.org or 530-747-8052. Follow her on Twitter at @elizabeth_case