State health officials preach prevention and defense as mosquito complaints hit record levels in Maricopa County.
The Dalai Lama once said, “If you think you are too small to make a difference, try sleeping with a mosquito.”
Or try living with 10,000 of them – that’s the record number of mosquito complaints Maricopa County received during a nine-week period last year.
Arizona plays host to 49 breeds of the midge, most of them merely annoying. But one type can carry West Nile virus, which last year struck 108 Arizonans and killed a dozen, according to Jessica Rigler, epidemiology bureau chief of the Arizona Department of Health Services. Officials are calling on the public to help minimize this pesky threat.
The county sprays for mosquitoes when bugs caught in traps test positive for West Nile, says John Townsend, manager for the Vector Control Division of the Maricopa County Environmental Services Department. Last year the county tested 25,723 traps, with 198 positive for West Nile.
It’s impossible to predict how many mosquitoes Arizona will see in a given year, Townsend says. University of Arizona researchers Cory Morin and Andrew Comrie authored a study suggesting climate change could mean more mosquitoes, but Morin says the connection is complicated: Parts of the year could be too hot for mosquitoes, but we could also see a longer, wetter breeding season.
One thing is certain: Mosquitoes like the metro area now, with its heat island and plentiful pools and moist lawns. “A lot of mosquitoes wouldn’t be able to survive [here] if it weren’t for humans,” Morin says. Townsend also chalks up much of the tiny bloodsucker population to “people who want to live in the desert but also want lots of grass and vegetation all around their house.”
By May 2015, Townsend counted 1,419 complaints, with six traps testing positive for West Nile carriers. But he expects those numbers will skyrocket through summer and fall, particularly in July, the heart of mosquito high-season. Complaints peak when people get together to celebrate and barbecue. “That’s where the blood is,” Townsend says.
The county employs about 25 people who truck to sites that need to be sprayed. Scottsdale and Chandler saw the most county mosquito activity last year, but that’s not a constant, Townsend says: “Each year there seems to be one area of the county that has more activity. We aren’t sure why, but since West Nile is carried by birds, that may have something to do with it.”
The West Nile-carrying insect, from a genus called Culex, needs to bite a virus-infected bird before it can pass the disease to humans. About 20 percent of patients show flu-like symptoms, Rigler says, but a smaller number suffer meningitis, paralysis, encephalitis or death. “The real untold story about West Nile” is about 18,000 Americans living with the effects of the disease, says Joseph Conlon, spokesman for the New Jersey-based American Mosquito Control Association.
Culex has company here. Another mosquito breed that can spread two dangerous tropical diseases was spotted in Tempe about 14 years ago. Aedes aegypti, an aggressive biter that favors the human ankle, originated in Africa but is now found throughout the tropics. Unlike its night-biting Culex cousin, this critter is on bite patrol all day. Right now it’s a minority: Of 863,500 mosquitos trapped last year, only about 5.4 percent were Aedes, Townsend says. The diseases it spreads, chikungunya and dengue fever, usually don’t kill healthy patients. But they can cause painfully stiff joints and sometimes external bleeding.
That’s “two diseases we absolutely do not want here,” says Craig Levy, an epidemiologist with the Maricopa County Department of Public Health. “We would like to do everything possible to prevent that.”
The state has yet to see a homegrown case of either disease. Last year’s 25 chikungunya and 96 dengue patients in Arizona caught the disease abroad, many in Haiti. The mosquito carrier probably hitched a ride to Arizona from neighboring states in pottery or tires, Townsend says. Now that it’s here, it could bite an infected person and pass it to another.
Officials want you to stop mosquitoes where you live. Love of water unites the breeds. Culex prefers swimming pools to lay its eggs. “Those become like little swamps,” Townsend says. Aedis favors shallow water, like flowerpots and pet dishes. Drying up those water sources is the best way to control mosquitoes. Otherwise, Townsend says, “If you breed ‘em, you feed ‘em.”
“A single mosquito can infect every member of a family,” Levy says. “The government can’t fix all the problems. We depend on our local residents to do their part.”
How to Fight the Bite
Fix leaky sprinklers, hoses and outdoor faucets.
Spill water from flowerpots, watering cans, pet dishes, old tires and other sources. Wipe them with a rag to make sure you kill the eggs.
Clean vegetation and debris from stagnant pools.
Stock your pool with the mosquito-eating gambusia fish. Call Maricopa County Vector Control Division’s West Nile virus hotline (602-506-0700) to schedule a pick-up for free gambusias.
Make sure screens are hole-free.
Spray your skin with products that contain the insect repellent DEET.
Wear bright, long-sleeved shirts and long pants.
Avoid being outdoors at dawn or dusk.
More tips: maricopa.gov/wnv
