Mosquitoes are eating East Valley residents alive, and the worst may be ahead. State and Maricopa County health officials are inundated with a record number of complaints, but they say most of the mosquitoes they’re finding are the floodwater variety spawned by the heavy summer monsoon and not loaded with the deadly West Nile virus.
Although it has been a relatively quiet year for the mosquito-borne disease, new lab work shows West Nile is on the rise.
Thirteen human cases of the virus have been reported in Arizona so far this season, including nine in Maricopa County. Another 13 local mos- quito samples tested positive for West Nile this past week, including a batch in Tempe, bringing the county’s total to 29. Three new human cases were reported in the past week in Pima and Pinal counties.
That compares to 106 human cases, with four deaths, in 2005; and 391 human cases, with 16 deaths, in 2004.
But when you’re facing down a swarm of hungry mosquitoes, those statistics may be cold comfort.
“In some cases, people are experiencing mosquitoes on a biblical scale,” said Craig Levy, manager of the vector-borne and zoonotic diseases section of the state Department of Health Services.
“The samples that are coming in for testing are not coming in in little vials,” Levy said, “They’re coming in in Mason jars.”
At the county’s vector control program, manager John Townsend said the phones are ringing constantly with tales of mosquito woe, totaling about 900 a week. Employees work overtime and no summer vacations are approved.
“We try to get out as fast as we can to see what’s going on in that area,” Townsend said. “This is the time you have to be ready to work as many hours as needed.”
Once the area has been searched for standing water or other possible breeding sources, a mosquito trap will be set. If the trap brings at least 300 mosquitoes overnight — or 20 or more of the variety that most commonly carries West Nile — the neighborhood will be scheduled for insecticide fogging and possible larvacide treatment.
Some of the traps are holding 20,000 of the little bloodsuckers, and it doesn’t take long for county workers to figure out the worst areas.
“If they get eaten up while setting a trap, we’ll go ahead and fog it,” Townsend said.
Most of the mosquitoes tormenting the Valley are the psorophora species, which breeds in just three days, but usually doesn’t transmit the West Nile virus. These nuisance mosquitoes follow monsoon rains that leave behind stagnant water in puddles, buckets, toys and wheelbarrows. Eggs will hatch all at once after the storm hits.
“They go from zero to a million overnight,” Townsend said. “If we keep getting these rains, that’ll hatch off another batch of them.”
There’s a chance of rain in the Valley this weekend.
West Nile is spread by the culex mosquito, which takes about a week to go from egg to adult. The culex lives longer and tends to feed at night, while the psorophora mosquito will bite day and night.
Areas of the southeast Valley, such as Queen Creek, are particularly hard-hit thanks to fields, irrigation and construction projects.
“They know how to breed mosquitoes out there,” Townsend said.
Mark Schnepf takes matters into his own hands each summer at Schnepf Farms in Queen Creek. The Schnepfs attach a fogging machine to a tractor and spray their 300 acres every three days, in addition to using larvacide in puddles and ditches. “It started a little earlier this year, and they hit very hard,” he said. “One day they weren’t there, and the next day they seemed to be all around us.”
Health officials say mosquito season is at its peak, and will likely continue into October, tapering off as monsoon conditions decline and the weather cools off.
In the meantime, the usual mosquito precautions apply — eliminate standing water around your home, wear insect repellent with DEET and stay indoors during the prime feeding times from dusk to dawn.
The only mosquito-borne virus fatality so far this year was due to St. Louis encephalitis. But the man, in his 40s, had other health problems that likely contributed to his death on May 14.
The epicenter of West Nile this year appears to be Idaho, with 545 human cases and six deaths.
The encephalitis viruses are spread through mosquitoes that feed on infected birds. But most people bitten by infected mosquitoes won’t develop any symptoms. With West Nile, about 20 percent of people will develop flulike symptoms and fewer than 1 percent develop encephalitis. Those considered most at risk are the elderly and those with compromised immune systems.
• For information or to report a mosquito problem or get free mosquito-eating fish, contact Maricopa County Vector Control at (602) 506-0700, or go to
• You also can find information online at www.westnileaz.com or call a 24-hour hot line at (800) 314-9243 or (602) 364-4500.
IN YOUR YARD:
• Don’t allow water to stand for more than two days.
• Check for standing water in birdbaths, pet dishes, buckets, cans, cups, outside toys, wheelbarrows, old tires, boats and flowerpots.
• Remove any water that collects on pool covers.
• Clear leaves and twigs from eaves, troughs and gutters.
• Fill in low areas in lawns.
• Repair leaky pipes and outside faucets, as well as damaged windows and door screens.
• Let your neighbors know about potential mosquito breeding grounds on their property, or report stagnant water to the county.
TO REDUCE THE CHANCES OF GETTING BITTEN:
• Stay indoors from dusk to dawn, when mosquitoes are most active.
• Wear loose-fitting clothing, long sleeves and long pants.
• Apply insect repellent containing DEET to clothing as well as exposed skin.
• Do not use insect repellent on children under 2.