County health officials warn about the threat of West Nile virus
“Mosquitoes are more than just a nuisance,” says county vector control manager Paul Binding. “They’re the most dangerous animal on the planet.”
As proof, he gestures to an infographic on his office wall from Mosquito Awareness Week last April. Each year on average, 10 people worldwide die from shark attacks, and 10 are killed by wolves, Binding notes. And 425,000 people are killed by other people, making humans the planet’s second most dangerous animal.
“Mosquitoes kill 725,000,” Binding says. “A lot of those are children killed by malaria in Africa.”
Thankfully, Santa Cruz mosquitoes don’t pose quite that same level of deadly threat—most of the deaths worldwide each year are from primarily African diseases like malaria.
But Binding says that with global warming, the threat of mosquitoes in years to come could change dramatically in Santa Cruz. Now that mosquito season is in full swing, and the first bird of the season was found carrying the potentially lethal West Nile virus this month on Soquel’s upper Rodeo Gulch Road, county health officials are stepping up their educational efforts.
Most people who contract West Nile virus develop no symptoms whatsoever. About 20 percent come down with a fever, combined with muscle pain, vomiting and a rash.
One percent of those infected—often the elderly—come down with a more serious neurological disease, like encephalitis, which causes inflammation of the brain, or meningitis, which causes inflammation of the protective membranes that cover the brain and spinal cord.
“The problem with West Nile virus is we’re not out to scare people, but we can’t predict who’s going to get the serious virus,” says Laurie Lang, senior health educator for the county.
The only way to conclusively diagnose the virus is with a spinal tap, and although there’s an approved vaccine for horses, there’s not one available for humans. For that reason, the best way for people protect themselves is the most obvious: avoid mosquitoes.
Health officials recommend using bug repellant, wearing long sleeves, staying inside around sunset, and dumping standing water that could be incubating mosquito eggs.
There have been no human-reported cases of West Nile on record yet in the county, although the virus accounted for 14 deaths in California last year. Birds first started testing for serious levels of West Nile in Santa Cruz County in 2010.
It’s the vector control department’s task to keep such problems in check.
In his office on Capitola Road, Binding stands in front of a wall-side chart of the vector control department’s missions and goals in educating the public and reducing mosquito habitat. Some are places people don’t think about, such as inside car tires. Binding explains that rubber tires often become the breeding ground mosquitoes love.
“They’re perfectly suited to catching rainwater and keeping it from evaporating, so they’ll breed mosquitoes from winter rains through the summer,” he says. “Leaf matter blows in there, and it gets very stagnant. They’ll breed mosquitoes all summer, and it’s very difficult to drain water out of tires if you’ve ever tried to do that.”
The drought has posed some problems this year, the first being that the arid winter and spring dried up many of the sloughs home to certain fish and other predators that chow down on the bugs. Another is that when people start conserving water, they often leave open buckets around their yard for days on end, providing a place for mosquitoes to hang out, breed, and lay eggs.
“You’ve got to be careful you don’t keep it in containers that are unscreened,” Binding says. “I save my shower water, but I don’t leave it outside for more than a couple of days because in a week, it’s going to be breeding mosquitoes. So, I apply it immediately to the yard.”
The department also deploys mosquito-eating bacteria in bodies of water with disease-carrying mosquitoes. Santa Cruz County Mosquito and Vector Control District doesn’t only focus on West Nile, though, or even just mosquitos, for that matter. Binding and his fellow workers work to control problems posed by other disease-spreading animals like ticks and rodents. Binding is also turning his attention to other looming threats, like the Asian Tiger mosquito, which has been found in Southern California and also the Aedes aegypti mosquito, which has been found in neighboring San Mateo County.
A native to Asia, the Aedes aegypti has white markings on its legs and thorax, and can carry dengue or chikungunya. It bites throughout the day, so if it ends up in Santa Cruz, it could find someone in the middle of the afternoon as they try to enjoy a chai tea on Pacific Avenue.
“That’s a game changer, because it not only bites during the daytime, it prefers humans, and it can breed in a Dixie cup full of water and also the saucers in plants,” Binding says. “The eggs resist drying and they can lay their eggs in the bottom of a plant saucer, and then it dries, and the next time it’s watered, you have a mosquito that’s very efficient at transmitting disease.”
[Editor’s note: The above article has been updated (8/1). We incorrectly reported that Aedes aegypti can carry malaria. It can carry dengue and chikungunya. We regret the error.]