SYMVCD Sprays Sacramento in Spite of Zero Human
• July 30, 2010: 3 human
cases in the state to date, 0 neuroinvasive cases, and 0
deaths. SYMVCD sprayed Sacramento County anyway.
• August 16, 2011: 12 human cases in the state to
date, 0 neuroinvasive cases, and 0 deaths. SYMVCD sprayed
Sacramento County anyway.
We consider even a single death involving WNv to
be tragic, and we urge people to take precautions from getting the
virus, to educate others about the virus, and to be on the lookout
for and dry up potential mosquito habitat. Then, the first
requirements of any public-health response to a potential disease
such as West Nile disease are that it should be effective and
involve less risk than that from the disease itself.
Unfortunately, aerial spraying is both ineffective
After the requirements of safety and efficacy we
believe that a public-health response must be a proportional
one. For example, surely nobody would urge strict quarantines
for all people in Sacramento and Yolo counties in a flu season in
which deaths from flu and pneumonia were happening at only a little
greater rate than the yearly average, which is over 7000 for the
whole state. Instead, such measures as more education, greater
availability of flu shots, etc., might be implemented. In many
situations, no action out of the ordinary would be taken,
particularly in a year in which the number of flu and pneumonia
deaths were on a rate toward a total well below the average of
around 7000, unless there was solid evidence that an actual epidemic
appeared to be imminent.
One very practical reason for a proportional
public-health response is that money can help the public the most
when it is spent in places where it can make the greatest
difference. We were reminded early of the extremely small
relative risk from WNv, with articles such as this one from another
state giving "a healthy dose of risk
reality" and emphasizing that that a "rational assessment of
risk, then, hints that the hype
about West Nile has been bigger than the threat."
Indeed, one reason there is a vaccine for WNv for horses but not for
humans is that the risk from taking a human vaccine would be greater
than the risk from WNv.
In the summer of 2010, however, SYMVCD took
extreme action by spraying approximately 167,000 populated acres in
South and North Sacramento – a grossly out-of-proportion response in
light of the dramatically lower number of human infections to date
According to the California Department of Public
Health, as of July 30, 2010, just
prior to the spraying, there had
been 3 human cases total in the state, none of which was
neuroinvasive, and there had been 0 deaths of people in California
with WNv in their system (the cause of death is often
something other than WNv). That was in contrast to 112 total
cases with 4 deaths of people with WNv in their system in 2009, as
well as 445 total cases and 15 deaths of people with WNv in their
system in 2008. The numbers since the virus entered the state
are posted here.
In 2011 SYMVCD
sprayed 64,619 populated acres in Sacramento County, but
the figures were still low this year -- WNv continues into chronic endemicity. As of
August 16, 2011, just prior
to the spraying, there had been 13
human cases total reported in the state, and there had been 0
deaths of people in California with WNv in their system
(again, the cause of death is often something other than WNv).
There had also been zero human cases in either Yolo County
or Sacramento County, with no activity at all in Yolo
County (no infected birds, no infected mosquito pools, no infected
sentinel animals , no infected horses), according to the official state WNv website.
This ineffective and
risky aerial spraying over populated areas
was done at a cost of over $490,000 for the two years, as indicated
by District officials.
Nationally the figures are also striking.
Here are figures for the country since 1999, with the first number
being the number of neuroinvasive cases and the second being the
deaths of people with WNv in their system:
These figures are available here.
As is apparent from the state figures, there
was a peak in California in 2005 with 880 total human cases and 19
deaths, and then the virus began receding into chronic endemicity with a
dampening sine wave (declining with some fluctuations), exactly what
knowledgeable entomologists told us would happen. Instead of
acknowledging the movement into chronic
endemicity, vector-control officials tell us that WNv is
"still in the area" and they therefore must spray. The
implication seems to be that if they don't spray we could have a
major outbreak and they therefore must spray until WNv has been
eradicated, but knowledgeable entomologists indicate that 1) such
late outbreaks have never happened anywhere WNv has been, and 2) it
is likely not possible to eradicate the virus. Moreover, these
entomologists tell us that the spray has a negligible effect on transmission to
humans anyway. Viruses like this, such as those for Western
Equine Encephalomyelitis and St. Louis Encephalitis, recede into chronic endemicity and we might
have mild outbreaks every 20 years or so. Those viruses are
likely still in California, but no special actions are being taken,
much less extreme ones.
How do vector-control officials justify their
actions? In addition to telling us that WNv is "still in the
area" and they therefore must spray, they modify their "emergency
aerial spray response" criteria to ignore human infections when
there haven't been any to date in a region in a given season, and
they then declare an "epidemic" based on the non-human
parameters. So, a metric that explicitly ignores the extremely
low human infection rates is used to trigger when to spray, even
though human infections are well below previous levels and are in a
downward overall trend. The District Manager has told
reporters the last two summers that it is important to spray to
"break the transmission cycle." We have asked what that means,
but we have received no response. We suspect that it is a
feel-good public relations statement to divert attention from the
fact that the spraying is being done for political and not health
reasons. We have also asked what the scientific evidence is
that adulticiding breaks the transmission cycle, whatever it
means. These requests are in addition to our requests since
2005 for scientific evidence of the efficacy of adulticiding.
We have been offered none, and we are confident there is none.
It seems that the only way to actually "break the transmission
cycle" would be to eradicate the virus, which is likely not
Why are our public health and vector control
officials failing the public in this way? Is it because of the
influence of money from the pesticide and chemical industries?
Is it because off-the-shelf and risky chemical treatments are easier
to implement than the more-labor-intensive and safe biological controls? Is it because
highly visible actions will increase the sense of importance by the
public of the District and assist with future funding? Is it
because the automatic reaction of some people is to treat problems
with chemicals? We have had similar questions in previous
years, but the extremely out-of-proportion responses last summer and
this summer have highlighted these questions like never
before. The cost of over $490,000 is a nontrivial amount of
tax money going to the purveyors and dispensers. $490,000
could give significant support to a local program to produce and
culicivorax and Lagenidium
giganteum instead of compounding previous lost opportunities for perfectly
safe and effective biological control.
We note elsewhere on this page that the Nashville
spray program was recently halted, and
spraying is not expected to be done in the future, precisely because
spraying is ineffective. Note the discussion as to how "it
took six years and a new director for the Metro Public Health
Department to finally use science, common sense, and their own
records to make wise decisions." Concerned citizens there are
now urging their Health Department to create detailed protocols like
those of many cities that do not spray, in order to "help avoid the
protocol failures they had in the past." Successes like this,
along with the many cities that do not spray, give some hope that we
might someday get sensible policy from our own public health and
vector control officials.
Last update 8/31/11.