RE: Need for data analysis by CDC

Regarding point #7 of Mr.Robbins' message is that using dead crows as a
surveillance tool is only useful in areas where crows are the most affected
species. Out west, for example, the primary vector for WNV is likely to be C.
tarsalis, a species which feeds primarily on mammals. So it is not
inconceivable that the corvids could be largely unaffected compared to the
eastern half of the country.

As far as the efficacy of larvacide and adulticide mosquito control, in Ohio
we have seen Lake County initiate mosquito abatement as soon as WNV was
reported in the state and they experienced about 7 positive human cases.
Cuyahoga county, right next door, uses no abatement program and experienced
over 300 positive human cases. Cuyahoga also has a larger human population,
so perhaps these numbers are not as valuable as they sound, and certainly many
cases go unreported as well as the fact that under random (sera) testing (if
it were done), many cases would test positive that are not indicative of
infection but merely exposure. In other words, we always have more questions
than answers!

In Central Ohio, we are making a concerted effort to encourage communities to
initiate abatement programs beginning early next spring using bacterial
larvacides and the species-specific trypsin modulating oostatic factor
compounds being developed that interferes with the female reproductive cycle
in mosquitoes, as well as eliminating potential breeding sites. As the
drought here finally proved to many non-believers in this area, some species
thrive during dry conditions because what breeding sites there are are heavily
concentrated with the organisms the larva need and they tend to survive in
tenfold numbers as they also have little preying on them.

Barbara Ray
Ohio Wildlife Center

>

>
>
> norman robbins wrote:
> >
> > Dear West Nile List-Servers,
> >
> > As a scientist, I am greatly disturbed
> to read lengthy
> > discussions and CDC or State recommendations
> for WNv actions that often
> > appear to be based mainly on opinion rather
> than citations of statistical
> > validation. As much as one prefers
> prospective studies, could a thorough
> > and sophisticated CDC retrospective analysis
> of activities (e.g.
> > larviciding, adulticiding in 1999-2002) and
> resulting mosquito density and
> > human disease, shed some light on questions
> we will once again be debating
> > in the next few months?
> >
> > I encourage List-servers to revise or
> expand the following list of
> > questions in the hope that a collated version
> can be signed by you and
> sent
> > to CDC advocating that they use resources to
> investigate these issues. My
> > sense is that the CDC people are not at all
> resistant to undertaking this
> > analysis -- they just need outside advocacy
> to gain the resources.
> >
> > QUESTIONS FOR CDC TO INVESTIGATE BY ANALYSIS
> OF WEST NILE DATA TO DATE:
> >
> > What is the STATISTICAL EVIDENCE AND
> PROBABILITY RANGE (not opinion) that:
> >
> > 1. larviciding (at WHAT intensity and
> frequency) reduces mosquito
> > populations (by species)?
> >
> > 2. URBAN adulticiding (at what intensity,
> frequency, area and method)
> > reduces mosquito populations, by species and
> for how long?
> >
> > 3. there are (or are not) acute or chronic
> human health effects of urban
> > adulticiding in typical ULV amounts and
> frequency?
> >
> > 4. certain types of public messages or
> policies are more or less effective
> > than others in reducing urban standing water
> (residential, public spaces,
> > etc.)
> >
> > 5. one or another type of surveillance (dead
> crows, gravid or C0-2/light
> > traps, virus-positive mosquitoes, etc.)
> predicts human disease with what
> > kind of probability range.
> >
> > 6. both gravid and C02/light traps are
> desirable for human disease
> prediction.
> >
> > 7. there is some level of mosquito density
> which predicts risk of animal
> or
> > human disease and calls for more aggressive
> mosquito management
> >
> > Norman Robbins
> > Shaker Heights (OH) West Nile Task Force
>
>
Received on Thu Nov 14 23:11:01 2002