California is seeing the worst year ever for West Nile virus, and Sacramento County appears to be the epicenter.
To date, 312 birds statewide infected with the virus have been found dead, compared to 688 all last season — and this season started early. Birds with West Nile virus show the virus is present.
This year, the virus was identified in dead birds and mosquitoes two months earlier than in previous years. The season typically runs from early July to late September.
Of those 312 dead birds, 214 tested positive in Sacramento County. San Joaquin County has seen only 15 cases.
Galt has been relatively spared, with only one infected bird found within city limits, according to Fred Goethel, who represents the city on the Sacramento-Yolo Mosquito & Vector Control District board.
In the last two weeks, however, there have been 13 dead birds found in and around neighboring Wilton. Goethel said many were along Grant Line Road.
Public health officials have warned that counties could see a 200-percent increase in West Nile virus cases this year due to a warmer than usual winter combined with new reporting protocols causing significant delays in treating mosquito breeding grounds.
In addition to the early arrival of mosquito season, California counties have seen a 183-percent increase in the detection of WNV; a 413-percent increase in the number of dead birds due to the virus; and a 750-percent increase in the detection of WNV in mosquito samples, according to the Mosquito and Vector Control Association of California.
"This is a public health crisis in the making," Ken Bayless, association president, said in a press release. "We are facing one of harshest mosquito seasons in years, and we are seeing a dramatic increase in the number of mosquitoes carrying WNV."
West Nile virus is transmitted to humans and animals by the bite of an infected mosquito. The risk of serious illness to most people is low, according to the state Department of Public Health.
However, some individuals — less than 1 percent — can develop a serious neurological illness such as encephalitis or meningitis. People 50 years of age and older have a higher chance of getting sick and are more likely to develop complications. Recent data also indicates that those with diabetes and/or hypertension are at greatest risk for serious illness.
There has been one confirmed human case statewide this season, as of Friday. It was reported in Kern County last month and was not fatal.
New regulations that came into effect last January require vector control officials to seek a National Pollutant Discharge Elimination System permit before treating standing water infested with mosquito larvae.
The new regulations require 24-hour background sampling prior to treatment of water bodies at 18 sites for each active ingredient of the pesticide being applied. Technicians must then re-sample the ponds within 24 hours and seven days after implementing the prevention measures.
However, the Mosquito and Vector Control Association of California said this process is hampering efforts to combat infected mosquitoes.
The life cycle of a mosquito is extremely short; larval eggs become flying adults in just three to five days. Because of the extreme time sensitivity, targeted spraying of standing pools of water infested with mosquito larvae must take place within a 72- to 96-hour window to avoid the need for spraying adult pesticide over a much wider geographic area, according to the association's website, www.mvcac.org.
Within five days, adult mosquitoes can emerge and fly more than 10 miles, where they can lay eggs on new standing water.
Contact reporter Jennifer Bonnett at firstname.lastname@example.org.