Beware of the buzz
West Nile virus is coming on the wings of mosquitoes and birds. Is Butte County ready?
Along a patch of dirt road, beneath the shadows of the looming Sutter Buttes, a small wood shack sits covered in leaf- camouflaged chicken wire. Inside are 10 red leghorn chickens. When a truck rolls to a stop outside, they start squawking.
Two people step out of the vehicle wearing protective white suits and gloves and carrying small plastic cases. They walk to the little shack, open its door, and enter. The chickens flap their wings wildly and scurry in the opposite direction.
The man chases down and deftly grabs one of the chickens. It ruffles its feathers at first but soon settles down, as if it knows what’s about to happen. He then uses a tiny lancet to prick the bright-red comb on the chicken’s head. A drop of blood appears and is immediately smeared on a thin sample plate.
One by one, the pair—entomologist Matt Bell and mosquito control specialist Beth Vice—repeat the process with the other nine chickens. It’s a procedure they go through every two weeks in different locations. Later, in a UC Davis lab, the samples will be examined for evidence that the chickens have been infected by a mosquito-borne virus.
Behind the coop hangs a lantern-like, carbon dioxide light trap using an air suctioned funnel to collect adult mosquitoes so that if signs of the virus show up in the samples, officials will know the culprit area.
Bell and Vice, who work for the Butte County Mosquito and Vector Control District, are on the front line of a looming war against an especially virulent disease, one that is expected to arrive in Butte County this spring or summer. It’s not SARS, which has been much in the news recently, but rather the West Nile virus, which most people have heard or read about for the past two years but likely associated with outbreaks on the East Coast and in the Midwest.
What local people may not realize is that the disease has been moving slowly but inexorably toward the West Coast and Butte County, where it is certain to find conditions that are especially hospitable. With its many rice fields and wetlands and its warm weather, this is prime mosquito breeding country. And it’s just had its wettest April in some 20 years.
Butte County is also temporary residence for millions of birds, the animals that, along with horses, are most affected by the virus.
Local health agencies have been preparing for the virus’ arrival since it first appeared, in the Bronx Zoo in 1999. And because this is a mosquito-breeding area, they’re highly experienced at monitoring and controlling the pest. The chickens, which are technically referred to as a sentinel flock and are not unlike the proverbial canaries in the coal mine, comprise an early warning detection system designed to alert health officials to the virus’ presence.
But all of the local agencies involved readily admit that nobody knows for sure how much of a problem the virus will be when it shows up—or how many birds, horses and people will get sick or die.
The only confirmed human case of West Nile virus so far in California was one of last year’s surprises: a non-imported case in a woman who lived near the Los Angeles International Airport. Officials believe she may have been infected by a mosquito carried aboard an aircraft, but they are still not sure.
Then, last fall, signs the virus had established a West Coast presence were confirmed when several horses were found infected in the state of Washington. All have since recovered.
Here in Butte County, we live surrounded by some 45,000 acres of wetlands and 95,000 acres of rice fields that often hold standing water, a necessity for breeding mosquitoes, which means locals should be prepared for the worst.
“We don’t know which part of California will see the virus first. It could come from any direction—north, east, south,” said Vicki Kramer, chief of the Vector Borne Disease Section for the California Department of Health Services. “Right now, we’re just trying to conduct comprehensive statewide surveillance.”
Some local mosquito species listed as capable of spreading the virus (there are about six such species) are common in rural and suburban areas and are capable of passing the virus to their offspring. If the worst forecasts come true, we may begin seeing lots of dead birds (mostly crows, magpies and ravens as well as blue jays and raptors) and some sick horses, if the latter are not vaccinated in time. Then, of course, there are the possible human cases.
West Nile killed 284 Americans last year, which is 284 too many, of course, but needs to be put in perspective. Every year common influenza kills as many as 20,000 people, most of them elderly. And it’s important to note that only 1 percent of humans infected with West Nile die and that humans cannot spread the virus to each other.
West Nile is considered most dangerous for the elderly and small children, who have greater potential for developing encephalitis, an infection that causes brain swelling. In Africa, where the virus originated, you don’t see high levels of human mortality from the disease because most of the adults have been exposed to the virus since they were kids (with mosquitoes acting as flying vaccination agents).
When the virus hits California, most people who become infected will show only mild flu-like symptoms. Health officials are urging people not to be afraid or alarmist. At the same time, they suggest that anyone who believes he or she has been infected and has symptoms that are worse than normal flu, such as lingering fever, blurred vision or mental changes, immediately see a doctor (see sidebar for preventative measures).
There is no vaccine realistically close to being ready for human use. Horses are another matter.
With mechanical ease, Dr. Michele Weaver plunges a small syringe into the horse’s smooth neck. The big animal, a 20-year-old gelding named Toby, doesn’t flinch, though she chortles at the presence of our photographer.
We’re in the horse stable at Look Ahead Veterinary Services, located three miles south of Butte College in horse-rich Butte Valley. Weaver, a slender woman with long blonde hair tucked into a worn field cap, has cared for horses and other animals here for the last 11 years.
She’s well aware that West Nile virus is coming and in fact has vaccinated about 3,000 horses for the disease in the last two years. The good news is that the vaccine she’s been using, which was previously approved under an emergency “conditional license,” was fully approved by the U.S. Department of Agriculture last February and is considered effective in horses that receive at least two doses.
Because it takes six weeks for protective antibodies to build up in newly vaccinated horses, vets are recommending all horse owners get their animals vaccinated well in advance of mosquito season—and time is quickly running out.
“It’s an old disease,” Weaver explains. “Africa, Egypt, Europe have had West Nile for a long time, so they’ve made a good, worthy vaccine. “[The West Coast] is at the tail end of it, and we’ve been preparing for a while.”
Weaver says she is most worried about backyard-horse owners or other owners who have no contact with trade magazines, shows or other informative outlets. “I have a feeling there’s going to be some sick horses from hill people in here, and it’s going to be a shock to some people,” she explains.
The shots cost $27 each, and there are three series of inoculations—not a bad price considering that, if a horse comes down with West Nile, its owner is looking at hospital bills of around $1,000 or more to attempt to save the animal, Weaver says. Even then, she notes, the horse could still wind up “retarded” from brain swelling.
Veterinarian studies say the virus kills one in three infected horses. Statistics show it affected 15,000 horses nationwide last year alone (40 percent of those diagnosed with West Nile died or were euthanized) and has been found in 78 different species of birds. The ability or inability of different species to catch the virus relates directly to differences on the cellular level—which explains why cows are safe—and also to whether mosquitoes feed on them in the first place.
Other vulnerable animals also can be vaccinated, and health officials are working to protect such endangered species as whooping cranes and economically important flocks of domestic geese. For instance, the Sacramento Zoo recently followed the lead of other zoos nationwide by vaccinating its flamingos and zebras in hopes of controlling an outbreak.
On a cluttered wall in the Butte County Mosquito and Vector Control District offices, in a small building off Larkin Road near the Oroville airport, hangs a quirky little poem—it’s “An Entomologist’s Wife’s Toast,” by Maybelle Carter, and it’s dedicated to entomologists: “… of all the men I used to think would truly be the queerest/ the men who worked with little bugs/ but now I think them dearest.”
James Camy is somewhat of an expert on little bugs, especially mosquitoes, having studied and controlled their numbers here for the last 20 years. The appointed manager of the mosquito control district, he oversees 16 full-time employees and a few seasonal workers who work year-round studying local pest problems. Camy is likely the man many county residents will be calling if a West Nile outbreak occurs, but he doesn’t seem too worried.
“We’ve known ever since 1999 that it’s going to show up here,” Camy says. “We’re as prepared as we can be short of having more financial support to deal with it. … It’s tough to raise money right now in the public sector.”
Camy is concerned that his staff could be stressed if his employees start receiving an overload of concerned calls, but he still emphasized that his organization has a good handle on things. Funding for his office comes from a portion of local property taxes that he says is “not that much,” which means his office must be “judicious” about when and where it uses expensive chemicals.
The federal Centers for Disease Control gives surveillance money to each state to track West Nile virus, but mosquito control in California is primarily a local matter financed by local taxation, which works better as a sustained source of funding than federal means.
Camy’s office is littered with information on mosquitoes and other insects. On one wall is a map of Butte County with pins marking the seven different sentinel chicken flocks, 26 light traps and other testing areas, as well as pictures and cartoons of nasty looking mosquitoes. Behind his offices are several garages filled with pickup trucks and one hangar with three airplanes (each equipped with a different kind of sprayer) used to spread pesticides nearly every weekday of the summer season. Camy says certain vernal pool areas are so teeming with billions of mosquito larvae that they seem to be moving.
Most of the populated regions in the state operate mosquito control districts, though this one, with its three planes, is better equipped than most. There are some 55 special districts and a variety of municipal and county agencies that cover 60,000 square miles of California, using a strategy of integrated pest management to contain mosquito populations.
The overriding principle is simple: Get ’em when they’re young by killing mosquitoes in their aquatic or breeding stage. To do this, staff use a host of preventive measures, from surveillance and keeping standing water areas drained or changed (which they recommend all citizens do around their property), to installing mosquitofish in local ponds to eat the larvae and using “larvicide” in the water or products that contain insect growth regulators that prevent the larvae from becoming adults.
In the case of an emergency outbreak, however, pesticide chemicals and widespread fogging are sometimes the only methods of containment.
“We use pesticides only when we have to, and we try to stay away from people,” Camy says, adding that his agency operates under health and safety codes and everything it does is approved by the U.S. Environmental Protection Agency and the even more stringent California EPA.
Camy says the biological pesticides required extensive testing and are much safer and better designed than the harmful DDT used 35 years ago. He lists his top three: BTI (a common naturally occurring bacterium often used to kill caterpillars in home gardens), methorprene insect growth regulator (which mimics a natural insect hormone and disrupts the growth cycle), and pyretheroids (made from chrysanthemum flowers). The key factor in all these is concentration or dosage rates, and Camy says his experienced staff is perfectly capable of handling the tricky subtleties of spraying under different wind and temperature conditions. Two of the small prop planes operate by satellite guiding system for increased accuracy.
Still, whenever pesticides are sprayed, there are always different concerns.
“Pesticides that kill mosquitoes may also kill other animals—birds, mammals, fish, and other insects, including mosquito predators,” notes Dr. Charles Crabb, dean of the Chico State University College of Agriculture. “David Pimentel of Cornell University conservatively estimates the number of birds lost each year to pesticides at 67 million on farmland alone, with a potential for 10 times that number to be affected in other ways.”
Dr. Steven Schutz, an entomologist with the Contra Costa Vector Control District, insists that, because “ultra-low volumes” of pesticides are always used, there is little need to worry about fish populations or anything else that may be affected by drifting hazards.
He echoes Camy when he says that cooperation with property owners concerning water management (when and where they will be draining, for instance) is one of the best ways to control mosquitoes—heading off the problem before it has a chance to begin.
One person who is doing so is Rick Ponciano, ranch manager with Ken Hoffman’s Rancho Esquon in Durham. He prepared for this mosquito season by taking measures last year. His 8,000-acre ranch has more than 1,000 acres of wetlands. Neighboring landowners had expressed concerns about possible mosquito problems.
“We wanted to be a good neighbor, so we decided to step up to the plate,” Ponciano said, to the tune of $15,000 worth of restructured drainage so that mosquitoes numbers would be lower—"and they were last year,” he notes.
Agricultural Commissioner Richard Price says one of his main worries is people going haywire with indiscriminate pesticide use around their home.
“Before, when we had a St. Louis [encephalitis virus] outbreak, you started seeing lots of people in emergency rooms,” Price says. “People got [pesticide] in their eyes … little kids can get into it. I warn people not to go overboard around their homes.”
Price says that he has already had several local rice farmers express concerns at public meetings, both for the safety of their children and about measures they can be pursuing to control mosquitoes on their own property.
Camy and Price have voiced concerns at meetings, including the Butte County West Nile Virus Task Force, a group of concerned individuals and public agencies that has met four times already. It’s headed by the local director of health education, Carmen Ochoa.
“If a large number of individuals had serious WNV infections and had to be hospitalized, the Butte County health officer would immediately contact the Butte County Office of Emergency Services and the California Department of Health Services to determine if a local emergency would be declared. If so, then a determination would be made as to what county and state resources would be made available,” Ochoa writes via email in response to questions.
After a recent meeting in Oroville—which the CN&R was asked not to attend because the group wanted “to invite all media” if any were present—Ochoa and others, including county Health Officer Dr. Mark Lumberg, discussed concerns about West Nile with local and state representatives.
Afterwards, I was invited to meet with some participants, who unanimously agree that the important goal right now is keeping the public well informed and vigilant into the coming mosquito season. They say they are not panicked and are as prepared as possible, but they concur that all could change radically with a summer outbreak.
“Once a case is confirmed, we will begin following it closely,” says Lumberg. “We would immediately notify the public through media press releases and medical community training.”
Lumberg says he anticipates such communities as Biggs, Gridley, Richvale and Nelson might be among the first affected and that, if people are infected, they will most likely be the elderly, whose immune systems are less able to ward off infection.
“This will be front-page news when it happens. People are going to be worried,” continues Lumberg. “But I don’t believe we will exceed our [Communicable Disease Department] abilities to handle the problem. Our responsibility will be to advise the public on the risk level.”
“If we have a large-scale problem in California, funding could become an issue for smaller districts,” Camy added. “But we do have a statewide agency, and perhaps different districts would help out in outbreak situations. … Of course, if a public emergency is declared"—as one was in Louisiana last summer—"we’d have access to federal funds.”
In Louisiana, after human deaths were related to the virus (24 of 330 positive cases), an aggressive spraying campaign began that had the problem under control by mid-summer.
All mosquito control districts follow a statewide template issued by the state Department of Health Services, but California has the added bonus of a long-standing, well-experienced mosquito control program that makes it better prepared then most states the virus has hit so far, some of whom had to come up with mosquito control boards overnight.
Some articles on West Nile virus note that the disease could conceivably spread to cats, bats, chipmunks, skunks, squirrels, domestic rabbits and other species. The consequences of a hard-hit bird population could also result in overgrown rodent populations or other problems that would affect local farmers. But it is all speculation at this point.
Most experts believe the WNV scenario will likely be similar to another virus it closely resembles, the St. Louis encephalitis virus (SLE) mentioned above, which broke out in 1975 in the Midwest and killed 95 people. After the initial scare, infection rates quickly dropped off in the years to follow. The St. Louis virus is still around today, but as with West Nile, most people build immunity to the virus after exposure. So the real question is how much damage will be done in the initial years.
“Basically, we’re not sure, but the whole scope is out there,” says Dr. John Maas from the UC Davis School of Veterinary Medicine. Maas points out that two years ago Nebraska was hit hard with a large number of human cases that researchers believed was due to northern mosquitoes being better at vectoring, or transmitting, the disease.
“Being in Butte County, you could have a harder time with the northern mosquitoes than the desert regions down south because you have more water, more efficient means to spread,” Maas says. “In many ways, the WNV is about the same as the other viruses we are used to dealing with. But it does seem to be more active.”
Maas bristles when discussing the role of the national Centers for Disease Control, which he believes underestimated West Nile while taking drastic measures for such media fixations as anthrax, prescribing 300,000 doses of the top-of-the-line antibiotic Cipro when penicillin just as easily would have done the trick.
“The Centers for Disease Control has just watched [West Nile virus] happen,” Maas says. “All those other things, like SARS or anthrax, have been completely overblown, yet something like West Nile is under-blown.”
Dr. Roy Campbell, a medical epidemiologist with the CDC’s Division of Vector Borne Diseases in Fort Collins, Colo., says that it is California’s job to take care of mosquito control and that it has one of the best systems in place to do so. California has more mosquito abatement districts per capita than any state in the country, Campbell notes, so “in some ways they are well-positioned to intercept the virus, find it early with mosquito surveillance and control, and be better prepared than the rest of the country.”
Campbell says the CDC works in collaboration with state health departments, currently funding 54 different jurisdictions. “But if anyone says they know what is going to happen with this virus [in California], they’re wrong. … We just don’t know how big a health problem it’s going to be.”
Some of the most fundamental work on these kinds of viruses was done in the late-'30s in California, Campbell says, and “the grand old man of the process” is still around. Dr. Bill Reeves, an 86-year-old professor emeritus at UC Berkeley, has spent the better part of a century chasing such related and common airborne viruses as SLE, Western virus and Venezuelan equine virus around the world. He says he is concerned about what could happen with West Nile on the West Coast.
“Now, don’t scare people,” Reeves says during a call from his office. “The virus will appear here; it has spread like wildfire—and I’m not looking for a big epidemic. … Still, everybody is susceptible to this particular virus because it’s new, and I expect you’ll see some cases.”
Reeves also said that mosquito populations are lower in the valley since the heyday of SLE, when practically anyone over 60 years old had antibodies to the virus in their system (back in the days when people in Oroville added quinine to their coffee to starve off malaria and Anderson was considered the yellow-fever capital of America). But he adds that it does seem to be an especially bad year for governments to be decreasing vector-control budgets. If a large outbreak occurs, he says, there will likely be no other option than major spraying of adult mosquitoes, which he agrees always raises legitimate concerns.
“I wish the governor would get off his horse and let us know what he’s going to do," Reeves adds. "But, overall, I think here in California we’re pretty much on top of things, and we know what we’re doing."