L.A.’s West Nile hunter
The impulse to scratch is all-consuming. That subtle tickling sensation on an arm, an ankle, the back of the neck intensifies as swarms of mosquitoes -- all of them potential carriers of the deadly West Nile virus -- jump and flutter and pile onto one another. Fortunately, they’re confined to eight tightly cinched sacks.
Jennifer Wilson barely notices them as she drives, which is slightly alarming considering that the mosquito prisons dangle on hooks just behind her head, inches from her face. (“The morbidity” of the virus, she says dismissively, “is less than that of the flu.”) Still, the insects must sense her sweet-smelling perfume, her bare arms, the absence of insect repellent. It’s been hours since they had a “blood meal.” Surely, they’re starved.
But there will be no feeding. On this, their unluckiest day, these delicate insects are headed to a “deep freeze” refrigerator in Santa Fe Springs to be preserved for testing.
Welcome to the front lines in the local battle against West Nile virus, a disease that has infected more than 10,500 people nationally and killed nearly 300 in the last year. The virus is also perhaps the best thing to happen to a young ecologist like Wilson, who until recently only dreamed of such an epidemic.
“Around the world, you could be studying malaria or AIDS, but it’s just not going to get as much attention or funding right now,” she says during her Tuesday morning “virus surveillance.” “This is just such a once-in-a-lifetime opportunity -- a brand new disease, seeing how it responds to its environment and how people respond to it.”
Since May, Wilson has been clocking 16-hour days, shuttling between the lab in Santa Fe Springs and 20 bird and mosquito trapping sites throughout the county. A research associate employed by the UC Davis Arbovirus Research Unit, Wilson and four ecologists at the Greater Los Angeles County Vector Control District are charged with monitoring 1,350 square miles that include 33 cities and about 5 million people. They track the area’s “vectors,” or animals and insects known to carry or transport disease, in this case West Nile virus.
What was “a pretty mundane” routine is now “completely unpredictable,” Wilson says. Schedules must stay fluid because the virus moves rapidly. This month it traveled 600 miles -- from Southern California to Sacramento -- in two weeks. “We’re trying to pace ourselves, because we know it’s going to get a lot worse before winter hits,” she says.
Lately, Wilson has become something of a media darling, having to “squeeze in” research between ride-alongs with Channel 4 (NBC), Channel 5 (WB), Channel 11 (Fox), even the PBS show “Nova.” When one crew asked her to move her sentinel chickens “somewhere more scenic,” she says, Wilson fought the inclination to shout: “We’re trying to control an epidemic here, folks!”
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Driven, and driving
There’s something counter-intuitive about the title “Los Angeles ecologist,” and yet Wilson looks the part. Petite, with long blond hair and flawless skin, she smiles and laughs a lot, and when she spots mosquito larvae floating atop the water in one trap she gasps, “That is the coolest thing ever!”
Practically speaking, Wilson’s job is a lot of driving to and from tucked-away trapping sites, where she retrieves mosquitoes and birds and monitors the sentinel chickens, which serve as signals of the disease’s arrival. In the lab, she helps preserve dead birds and mosquitoes, classifying and testing them. It’s nothing that might inspire a Michael Crichton novel.
Yet Wilson maintains an exceptional sense of wonder for her world. Complex scientific explanations and overwrought Latin insect names come easily to her, and she uses them as if everyone speaks this language. She wistfully recalls her work with the Asian tiger mosquito, a “spectacularly beautiful” insect from southeast China, describing the “gorgeous white stripes going across their heads and across their legs.”
She speaks tenderly of crows, a dominant transporter of the virus, whose oil-slick coats and bad-omen vibe rarely evoke such emotion. They form “tight little family groups,” she says. And as a result they often get infected, plummet from their perches and “pass away” together.
“It’s so tragic what happens to these crows,” Wilson says. “It’s so sad. They have this seven-day period from the time they get infected to the time they pass away, and that last couple days they are paralyzed. They’re just blinking. There’s really not much they can do. And unfortunately they’re an easy meal for mosquitoes during that time too. Children have seen these birds on the ground and they think: Oh. I’ll make a pet out of it, it’s so tame. We had one little boy get bitten by a crow. But that was basically all the motor functioning it could even do. Poor crow.”
That compassion evaporates, however, when two nonchalant feral kittens cross the path of her truck as she drives along a golf course. It is these merciless killers, she says, who are responsible for low bird counts in a local wildlife preserve. “Feral cats,” she snarls. “They’re the scourge of the Earth.”
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Watching for dead birds
Birds bitten by West Nile-infected mosquitoes are believed to have spread the disease as they migrated during late summer and early fall. So scientists keep watch for the sudden appearance of dead birds, which may in turn infect new mosquito populations.
Despite this region’s arid climate, sprinkler systems, pools and spas have created soggy conditions ideal for mosquitoes. “The people living here have kind of changed the ecology of the area,” Wilson says. “What you’re seeing here is just a man-made problem.”
West Nile virus was first isolated in Uganda in 1937, and during the last six decades it has traveled the globe. Los Angeles officials have been braced for it since August 1999, when the virus first appeared on this continent in Queens, New York. They studied the seemingly unstoppable spread of the disease as it moved west last year -- an estimated 2,900 infected in Colorado, 1,900 in Nebraska, 1,000 in South Dakota, 720 in Texas.
A month after the first local case was confirmed, L.A. vector control specialists began fogging the Harbor Lake area with pesticides. Later, inspectors went door to door in neighborhoods checking for stagnant swimming pools, murky drainage ditches and over-watered lawns. They distributed mosquito fish in some, larvicides in others.
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Low infection rate
L.A.’s dense development actually helped control the virus. With a population that rivals most western states, the county has experienced a fraction of their infections, just 54 confirmed. Other western states, with large areas of irrigated farmland and poorly organized vector control, have suffered far worse.
Still, West Nile has moved far more rapidly than anyone anticipated. “We never really expected it to go from coast to coast in a span of less than five years,” says Wilson’s supervisor, Minoo Madon, scientific technical service director at the Greater Los Angeles County Vector Control District. “This is one of the fastest-spreading insect-borne diseases we’ve experienced.”
Wilson chats amiably all the way down the 110 Freeway. It’s around 9:30 a.m. and she’s explaining the fine art of mosquito wrangling. The trapping mechanism must be tailored to the species. For example, the Asian tiger mosquito prefers to alight near shrimp-rinse water -- something Wilson and her colleagues learned when that species hitched a ride in a “lucky bamboo” shipment from China.
Southern California’s natives -- Culex tarsalis (encephalitis mosquito), Culex quinquefasciatus (Southern house mosquito) and Culex erythrothorax (tule mosquito) -- prefer a nutritious concoction known as “stinky water.”
“We’re working on a study to perfect our stinky-water-making skills,” Wilson says. “The [fermented] rabbit chow has given us wonderful results. We used to be working with hay infusion, and it smelled horrendous. It was hay and lact albumen and yeast, fermented for a week. It was unbelievably stinky stuff. It was amazing.”
During the next three hours, Wilson makes eight stops around Harbor Lake near Harbor City, an area crowded by car dealerships, apartment complexes and parking lots. Every trapping site is within earshot of an oil refinery or a major freeway. It’s ecology, Los Angeles style.
The traps are extremely low-tech and look as though they belong in a high school science fair. A small plastic toolbox is balanced atop the tray of stinky water, which is used to lure pregnant mosquitoes that lay their eggs there. Once they land, a battery-powered fan sucks them into a plastic container inside the toolbox.
Another trap consists of a plastic-foam box containing a small packet of CO2 (dry ice), a battery-powered fan and a dangling net. The CO2 “attracts them as a breathing mammal would,” Wilson says, and the fan blows them into the net.
Wilson retrieves traps from the ConocoPhillips refinery, someone’s front yard, a chain-link fence in a parking lot, and a city maintenance yard next to a golf course. The swampy marsh around the man-made Harbor Lake produces the morning’s largest mosquito take: 1,200. But that catch is infinitesimal compared with the more than 20,000 netted from the same spot just three years ago. Routine insecticide treatments have decimated the population.
At one trapping site, Wilson admires an apartment building’s patios. They overlook a tennis court and a pool, and many of them are decorated with plants and wind chimes. There are lots of mature trees along the road, and despite the traffic headed for the nearby Kaiser Permanente complex, it’s peaceful.
“It’s a shame,” Wilson says, walking to the mosquito traps on the court’s chain-link fence. “All these mosquitoes are actively looking for blood meals.”
