West Nile Spraying Generates Controversy Locally


wnv-sprayingThis week, the Sacramento-Yolo Mosquito and Vector Control District announced that, due to “intense” West Nile Virus Activity, it would do some of the most intensive spraying and aerial treatments for adult mosquitoes infected with West Nile virus.”

On Wednesday and Thursday that occurred.

“We are moving forward with plans for aerial spraying” said Gary Goodman, District Manager. For the past few weeks the District has been monitoring these locations which became areas of concern due to the many mosquito samples and dead birds that tested positive for the disease. “Our surveillance results indicate very high infection rates among mosquitoes and the need to spray in order to protect area residents from the threat of West Nile virus” added Goodman.

According to their release from earlier in the week, the Davis block is approximately 20,000 acres and the boundaries are from County Road 29 on the north, down to Levee Road along Putah Creek on the south and from County Road 98 on the west to County Road 105 on the east.

They write, “Aerial treatments will be made using Trumpet, an insecticide registered for use in mosquito control by the US Environmental Protection Agency (EPA) and California EPA and routinely used throughout the United States to control mosquitoes. “

This triggered a local environmental group, Environmental Voices, to issue a warning about “Dangerous Pesticides Being Aerially Sprayed Over Densely Populated Davis and Woodland”

They write, “The chemical being sprayed is an organophosphate under the brand name “Trumpet.” The main component of Trumpet is Naled, which is a cholinesterase inhibitor containing DDVP (Dichlorvos). Naled is toxic to fish, birds, and other wildlife. DDVP is classified by the State of California under Prop 65 as a chemical that causes cancer (class 2B carcinogen). Individuals with certain medical and pre-existing conditions are the most vulnerable.”

They add, “Naled is also non-discriminatory and will kill beneficial insects including the highly vulnerable bee populations already at risk from neonicotinoids. While adding to the toxic chemical load of the human population, the further destruction of beneficial insects exacerbates the risks by eliminating the natural predators of mosquitoes.”

The site, Stop West Nile Spraying Now, argues that spraying does not work and it is dangerous to some people.

They write, “Public officials have exaggerated the threat of WNv in an attempt to justify their spray protocol.”

They add, “the Sacramento-Yolo Mosquito & Vector Control District (SYMVCD) has supplied no evidence that spraying adulticides is effective in slowing the transmission of WNv to humans. In fact, scientific research and mathematical modeling demonstrate that spraying is ineffective because mosquito populations quickly rebound to their prior levels. Even with this lack of efficacy the District refuses to resurrect its program of development of safe and effective biological controls.”

“According to a recent CDC announcement put out by CNN, about 80% of people who are bitten by infected mosquitoes will not show any visible symptoms or become ill in any way. Of the 20% who do show symptoms, only about .5 of 1 percent will develop more serious symptoms,” the groups stated. “And, most of these individuals have predisposing conditions, such as weakened immune systems. Statistically, this translates to a virtually zero percent chance that the average person will experience any health problems associated with WNv.”

In addition to these concerns, some Vanguard readers expressed concern that the communication between Vector Control and the citizens was lacking.

They point out that the FAQ page, for example, recommends that during aerial spraying citizens should stay indoors with the windows closed. And they sprayed with a more toxic and persistent pesticide this time, the organophosphate Trumpet, than they did in 2006.

Were residents caught unaware?

A Sacramento Bee article from mid-July indicates, “One UC Davis scientist says greater precautions should be taken when such chemicals are used, despite the department’s safety declaration.”

“The big concern is the long-term effects that might happen from low level non-acute toxic doses,” said Irva Hertz-Picciotto, environmental epidemiologist with UC Davis. “My concern is for young children and pregnant mothers.”

The Bee reported that Professor Hertz-Picciotto’s “concern arises from a study she co-authored that found a link between a pregnant mother’s geographic proximity to where pesticides are applied and higher rates of children born with autism.”

“In that study, the residences of women who bore children with autism were compared to residences of women whose children developed normally. It turned out mothers who bore autistic children were more likely to have lived close to where pesticides like organophosphates were applied to farm fields. Most of the women in the study lived in or near the Sacramento region,” the Bee wrote.

They add, “The study found that children of mothers residing near areas where pyrethroid insecticide was applied just prior to conception or during the third trimester were at greater risk for both autism spectral disorder or developmental problems.”

Another reader complained they biked home a short distance unaware of the spraying and “encountered severe burning in my eyes.” She wrote, “When I got home I rinsed my eyes with drops and today my corneas are somewhat irritated as would be consistent with a chemical burn. Exposing us to this spraying without any choice is WRONG and it is obviously not harmless.”

A number of residents also reported finding dead bees and other beneficial insects.

However, others pointed out, “Why are people more afraid of pesticides that have been tested and approved than they are West Nile? It does not make much sense.”

As others point out, the studies cited here show correlations between spraying and other factors, but does not prove causation.

As they argue, “Nobody is saying there is a clear link between pesticides and autism or cancer. Nobody has demonstrated that this use of a very low-dose pesticide is going to cause a specific number of cancers or increase in autism.”

The Mayo Clinic writes, “West Nile infection is caused by a virus transmitted by mosquitoes. Most people infected with West Nile virus don’t experience any signs or symptoms, or may experience only minor ones, such as fever and mild headache. However, some people who become infected with West Nile virus develop a life-threatening illness that includes inflammation of the brain.”

“Mild signs and symptoms of a West Nile virus infection generally go away on their own. But severe signs and symptoms — such as a severe headache, fever, disorientation or sudden weakness — require immediate attention,” they warn.

The Mayo Clinic recommends, “Exposure to mosquitoes where West Nile virus exists increases your risk of getting West Nile virus infection. Protect yourself from mosquitoes by using mosquito repellent and wearing clothing that covers your skin to reduce your risk.”

The overall risk depends on the time of the year, geographic region and time spent outside.

They note, “Even if you’re infected, your risk of developing a serious West Nile virus-related illness is extremely small — less than 1 percent of people who are infected become severely ill. And most people who do become sick recover fully.”

Those most at risk are those who are older than 50 and those who have a weakened immune system.

A CDC Study that was conducted in 2008 from the Sacramento Division of the California Department of Public Health found some support for spraying reducing the odds of infection: “Statistical analyses of geographic information system datasets indicated that adulticiding reduced the number of human WNV cases within 2 treated areas compared with the untreated area of the county. When we adjusted for maximum incubation period of the virus from infection to onset of symptoms, no new cases were reported in either of the treated areas after adulticiding; 18 new cases were reported in the untreated area of Sacramento County during this time. Results indicated that the odds of infection after spraying were ≈6× higher in the untreated area than in treated areas, and that the treatments successfully disrupted the WNV transmission cycle.”

They conclude, “Our results provide direct evidence that aerial mosquito adulticiding is effective in reducing human illness and potential death from WNV infection.”

—David M. Greenwald reporting


About The Author

David Greenwald is the founder, editor, and executive director of the Davis Vanguard. He founded the Vanguard in 2006. David Greenwald moved to Davis in 1996 to attend Graduate School at UC Davis in Political Science. He lives in South Davis with his wife Cecilia Escamilla Greenwald and three children.

Related posts

33 thoughts on “West Nile Spraying Generates Controversy Locally”

  1. Tia Will

    This time I am going to make a very prominent disclaimer. I have no special training in the areas of infectious disease or toxicology beyond what is necessary to obtain a medical degree and the experience gained through 30 years of practice. My comment is also not intended to either support or object to the practice of arial delivery of known toxins for what is believed to be a more critical purpose. I am writing to point out a difficulty with risk assessment and determination of causation.

    In the current situation, the risk of West Nile Virus is known, verifiable by tissue sample, and quantifiable. Here we have facts that we can point to.
    With regards to the risk of the blanketing an area with a pesticide there are a few knowns, and many unknowns:

    First the known:
    1) The main component of Trumpet is a toxin and carcinogen. This is not in dispute.
    2) We know the maximal concentration of the substance at the time it leaves the aircraft

    Now the unknowns:
    1) Concentration at which the various toxicities occur
    2) Maximal concentration that any member of the public may be exposed to
    3) Effects on individuals with increased sensitivity ( infants, fetuses)
    4) Duration of effect
    5) Period of time until the effect can be detected

    One problem in attempting to compare risks is that while the occurrence of acute West Nile Virus illness is relatively soon after the exposure and has definitive diagnosis, this is not true for potential effects of a chemical exposure. In the case of a contact irritant, unless we have the ability to re-challenge and get the identical set of symptoms, we cannot prove definitely what the causative agent was. A biopsy will show only nonspecific inflammation.

    Determining whether a particular chemical caused cancer is even more difficult since we are typically looking at a lag time of years between the exposure and the diagnosis thus making it hard to prove causality until the number of cases becomes so large that the effect is irrefutable. Linking autism to toxins is a much trickier proposition since the effects would not be seen until years after the harmful exposure, the broad spectrum of the disease, the mobility of the population, the difficulty in setting up controls to evaluate other confounding factors does not lend itself well to the determination of causation. Thus, what may appear to be a harmless practice, may indeed be harmless, or may have consequences just as devastating as West Nile Virus for a few affected individuals….but we will just not know it.

  2. Anon

    I happen to be one of those people that mosquitoes love. Anytime I go outside anywhere near a mosquito, they make a beeline for me as if I were filet mignon. For some reason, which is still not well understood, particular individuals are more prone to being bitten than others. So I am glad they are spraying, but take the precaution of staying indoors when they are doing it. It is a risk assessment. Are people more at risk of being bitten and contracting the disease or more at risk from the spray? My guess is the greater risk is in not spraying, because without it, I suspect the mosquito population would get very out of hand quite quickly. Part of the problem is all the ponds we have around town. They are lovely to have, but they also are a mosquito magnet.

      1. Anon

        I have tried to research why some folks get eaten alive while others are almost never bitten, but have never been able to come up with a definitive answer. At one time I used to think it was very fair skinned people that got bitten, until I talked the matter over with a close African American friend who said she too was eaten alive. I have read lots of articles on the subject, but no one seems to definitely know the answer as to why some people attract mosquitos like magnets, while others can go virtually unscathed. In my own family, my brother was like me, and got nailed every time, while my sister went virtually unbitten. Go figure! Very frustrating to be a mosquito’s next big meal!

        1. South of Davis

          Anon wrote:

          > I have tried to research why some folks get eaten alive while
          > others are almost never bitten

          I have also tried to find out why I am a target. If the average person gets one mosquito bite at a Bar-B-Q I’ll get 10 (Over the counter OFF spray barely helps at all or the DEET based stuff I smuggled back from my last trip to Central America is only a little better) and it is not just mosquitos, fleas and ticks also like me more than most other people. We all lived through the medfly spraying 30+ years ago so I don’t think we need to worry much about this spraying (it is not like the “infants & fetuses” Tia worries about are out and about when they are spraying…

          1. Tia Will

            South of Davis

            The infants I will concede to you. I however, was not aware that there was any special moratorium on pregnant women being out in the evening when spraying may occur nor gardening the next day ; ).
            After all some of the critical brain development is occurring before the woman has even recognized that she is pregnant.

        2. tj

          VITAMIN B —- Years ago I read that people with higher levels of vitamin B are
          bitten less by mosquitos. I tried taking vitamin B and found it
          to be a great help for me. All of a sudden they ignored me.

  3. DurantFan

    As I approached the Davis Food Co-op one evening ths week, I observed the mosquito abatement plane spray over the open courtyard and produce storage area in front of the store. Is the organic produce stored/displayed there at that time still considered to be organic? Are all of the organic gardens within the spray area at large also still considered to be “organic?” Just asking.

    1. Don Shor

      They should have covered or moved the produce. I’m surprised to learn that it was out in the open on a night when it was known that pesticide was going to be applied. No, if it was sprayed then it’s not organic, I’d say.
      As to your own garden, the best thing I can say is that you gardened organically. How you feel about the vegetables and fruits in your garden now is really up to you. The material is washable, so rinse your produce before you eat it. The next fruits and vegetables that form will not have residue on them, and the material is not systemic.
      This is a real issue for organic farms. In some areas, they can submit a ‘do not spray’ form to the appropriate agency, but I don’t know if that’s an option locally.
      I really don’t know why the agency chose to use an organophosphate this time. Usually they use pyrethroids.

      1. Robb Davis

        Don – the response to your question about pyrethroids from the SYMVCD is that mosquitos have developed resistance to them. The City Council will be having an information item on spraying later this month (I think it will be on the agenda for the only meeting in August) and I want to ask about this. I am curious whether ultra-low volume dispersal hastens the development of resistance. I have also not seen (yet) epidemiological data on numbers of cases of WNV in Yolo County and have not heard of any deaths this year. The CC item will be informational in nature and enable us to understand the role of aerial spraying in the integrated vector control efforts. For those who are interested, here is a link to a CDC/MMWR document on human exposure to naled, permethrin, and d-phenothrin: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5421a1.htm

          1. Robb Davis

            Thanks eastdavis… I could have found this but did not look. Interesting, no human cases in Yolo County as of 8/8. Thanks again.

        1. Davis Progressive

          robb – thanks for posting. it seems like there are enough complaints that this wasn’t handled well. i’d really like to see evidence that spraying does anything to reduce the mosquito population.

          1. Robb Davis

            The article cited at the bottom of David’s article has links to several studies concerning impact of aerial spraying on mosquito populations. I have not had time to read them.

        2. eastdavis

          The mosquito management plan posted at http://www.fightthebite.net/ under the media tab, includes decision flow charts that help explain how the district decides when to spray. Although there have not been any human cases in Yolo County, there was a large number of mosquitos and birds found to test positive for west nile (148 and 30 respectively) over the recent week(s). The mosquito management plan SYMVCD website is dated 2005.

          It is interesting to note that the Solano County mosquito abatement district is completing a programmatic environmental impact report for their mosquito control program and the draft EIR is posted on their website and dated April 2014 (see http://www.solanomosquito.com/). I have no idea why Solano County is doing a full blown CEQA analaysis (EIR), while it appears there has been no comparable CEQA analysis on the SYMVCD website for their mosquito management program. Does anyone know why that is?

  4. Rich RifkinWDE 73

    The site, Stop West Nile Spraying Now, argues that spraying does not work and it is dangerous to some people. They write, “Public officials have exaggerated the threat of WNv in an attempt to justify their spray protocol.”

    I looked up the owner of that website. It’s the property of Jack Milton of Davis. There is a UC Davis math professor with that same name, and probably is the site’s proprietor. He has written various complaints about spraying by the vector control district going back 8 years.

    Registrant Name: Jack Milton
    Registrant Organization: stop west nile spraying now
    Registrant Street: 2406 Rivendell Ln
    Registrant City: Davis
    Registrant State/Province: CA
    Registrant Postal Code: 95616
    Registrant Country: US
    Registrant Phone: +1.5307586796

    Also, the Davis 9/11 Truth group, which believes a wide ranging conspiracy, including the U.S. government and Jews, were responsible for the World Trade Center destruction and other 9/11 acts of violence. A Jack Milton seems to be involved with that group, too. I have no way of knowing if it is the same Jack Milton. There is only one person in Davis on “white pages” with that name.


    1. South of Davis

      Rich wrote:

      > Also, the Davis 9/11 Truth group, which believes a wide ranging conspiracy,
      > including the U.S. government and Jews, were responsible for the World Trade
      > Center destruction and other 9/11 acts of violence.

      Most of the people that believe all of that also believe in “cemtrails” (where the government controls us by spraying mind altering chemicals out of jet planes) so it makes sense that they would be against any aerial spraying (aka “government mind control through chemistry”)…


    2. Davis Progressive

      jack milton is a math professor at uc davis, and a pretty smart man.

      interesting that two days ago you were railing against me and now you are outing a private citizen and impugning him with speculation and conjecture. pot meet kettle.

      1. Mark West

        “interesting that two days ago you were railing against me”

        Rich called you out for making a personal attack while hiding your own identity. Unlike you, Rich signed his name, giving the aggrieved party an opportunity for recourse if so inclined.

        1. Davis Progressive

          given rich’s unstable nature, why would i sign it under my own name?

          at least the two people i cited were public officials, not private citizens.

          1. Rich RifkinWDE 73

            Calling me unstable is more of your libel. I am a perfectly serene person. I simply get upset when an [edit] like you thinks it is okay to make up stories like you did about Katherine Hess and Ms. Namazi and you offer no evidence to support your position.

            In contrast, I made up nothing about Mr. Milton. I also never “outed” anyone. I reported exactly what is in the public record about him. He can stand by his views on his own.

          2. Rich RifkinWDE 73

            “the two people i cited were public officials.”

            The two people you attacked are government employees. Neither one holds an office. You are morally weak to hide behind a fake name and launch your petty attacks on people by name. Just because someone works in city government does not make it okay to lie about them, as you have done.

          3. John

            Rich, DP cited his sources, Steve Tracy and members of the City Council, all of whom were directly involved with the process. Is your issue with the opinions that those primary sources chose to share with DP, or is it with the fact that DP has relied on the statements of those primary sources?

          4. Davis Progressive

            “Calling me unstable is more of your libel.”

            i don’t know what you want to call it when someone grossly overreacts to a public posting to the point where you were practically making threats.

  5. Clem Kadiddlehopper

    Won’t someone think about the poor endangered mosquito? This majestic creature used to roam the Sacramento valley in the billions, but thanks to eradication efforts and habitat encroachments in now roams the valley in slightly fewer billions! You know what the problem is? It’s fair weather environmentalists! Oh sure, it’s easy to get behind an endangered animal when it’s cute and fuzzy! But they’re nowhere to be found when it has six legs, sucks human blood and helps spread a deadly disease! I suppose if another spraying program is enacted, they won’t be down at city hall protesting! Won’t someone think of the mosquitoes?!

    1. Frankly

      LOL! I think the life span of a mosquito is about 2 weeks, and I would bet that the older ones and the younger ones are the first to die with our light dusting of pesticides. So, again, our society is favoring the baby boomers.

  6. eastdavis

    The mosquito abatement district has an obligation to adequately notify the public of these spray events to reduce exposure risk. It’s obvious that the current means of communication has not been adequate and more needs to be done to get the message out. One commenter on this article on Vanguard’s FB page noted getting a severe rash and having to go to the ER after the spraying last week. Further, the California Department of Health Services notes aerial sprayings can pose risks to sensitive groups such as people with: allergies, asthma or chronic respiratory conditions, compromised immune systems, and pregnant women and small children. These risks can be mitigated by notifying the public to avoid exposure by staying indoors and closing windows. Perhaps the City of Davis can play a role in notifying the public when a spray event is scheduled.

      1. Mark West

        Is the City doing the spraying (or responsible for requesting it)? If not, they are not responsible for doing the notification, and as they can at best only be passing on second hand information, any efforts to be involved in the notification process will only add confusion.

  7. eastdavis

    Anon that is a good question which I don’t have an answer to. Certainly better coordination with the municipalities affected before a spraying could facilitate getting the message out to the populace. Certainly, there are ways to get the message out. For example, before an election, interested parties have no trouble contacting me via phone on how to vote. The city of Davis has no problem mailing me notices for water rate increases. And a few weeks ago when an elderly man went missing from Rancho Yolo, a helicopter was flying through our neighborhood announcing via megaphone that this man was missing. I’m not suggesting that any of these means should be used, but with a little thought and coordination, methods could be identified and employed that would more effectively reach the populace.

    1. David Greenwald Post author

      Here’s something – I get all of the city communications – text messages through Nixle, I’m on the city’s email list – I just searched again, and I don’t see any city-based communications.

Leave a Reply

X Close

Newsletter Sign-Up

X Close

Monthly Subscriber Sign-Up

Enter the maximum amount you want to pay each month
Sign up for