Homeowners can anticipate spraying to start Thursday around 8 p.m. and be finished two hours before sunrise Friday in areas of south Star, southwest Eagle, around Eagle Island State Park and southeast Boise, according to a news release from the Ada County Commissioners, which approved the move Tuesday.
“Gem County and Canyon County have seen it, so we’re just on the verge of seeing it here,” said Jim Tibbs, commission chairman.
No mosquitoes with West Nile have been found in Ada County so far. But Culex mosquitoes, which carry and transmit West Nile, have been doubling each week, said Brian Wilbur, director of Ada County Mosquito Abatement, from 31 in 2014 to 947 so far this year. The number of overall mosquitoes caught in traps grew from 284 in 2014 to 4,035 so far this year.
Ada County Mosquito Abatement has been conducting ground fogging, but it can’t keep pace with the growing number of mosquitoes, Tibbs said.
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WHAT ARE THEY SPRAYING?
Ada County officials say Dibrom concentrate, the pesticide that will be sprayed to combat mosquitoes, is not harmful to humans or pets in the dosage being used — one-half of an ounce per acre.
Homeowners with gardens in the spray zone should wash their produce before eating. If people are exposed, they should wash with soap and warm water. There is no need to cover swimming pools, but fish ponds should be covered with tarps and removed after the spraying ends.
Dibrom concentrate is lethal to bees, which is why spraying will take place at night when the insects are not active, Wilbur said.
The Idaho Shakespeare Festival is in the spray zone, but pilots will avoid the area during performances.
This will only be the third time Ada County has sprayed for mosquitoes since West Nile arrived in the state about 10 years ago. The county abatement district was formed in 1974.
A Wednesday press release from the county compared the other two years when spraying was done, including 2013, when seven infections were reported in Ada County. “That was a distinct improvement from 2006, when Idaho led the nation with almost 1,000 infections (more than 250 in Ada County), contributing to 23 deaths statewide,” the press release states. 2006 was also the first year the county sprayed for the insects.
West Nile infections had plummeted statewide shortly after 2006, however, and 2013 was actually something of a high-water mark in recent years. In 2012, only two West Nile infections were reported in Ada County; in 2010, that figure was zero.
Wilbur said Wednesday that several things factor into the decline in West Nile cases since 2006. He believes proactive spraying has played a role. But so has the pattern of the disease, which flares up when it initially enters a region, then settles down after most of that area’s population is either infected or found to be immune.
Cases also aren’t reported to the Idaho Department of Health and Welfare unless a patient is specifically tested for West Nile, he noted. So “we know that it’s heavier than what the numbers show,” he said.
Most people infected with West Nile show no symptoms. About one in five end up with a fever, headache, body aches, vomiting, a rash or other symptoms; a few — less than 1 percent — develop a serious inflammation of the brain that can cause permanent damage or death.
CLARIFICATION: This article should have originally specified that authorities say the pesticide is safe for a certain dosage being used.