Non-avian vectors and rapid spread of WNV

Lili Pintea-Reed pinteareed at madbbs.com
Tue Aug 12 12:54:59 EDT 2003


Isn't West Nile one of those viruses that spread serum to serum.? In other
words if exposed to desication in open air it dies. Much like HIV. Actually
very vulnerable in transmission in that it has to stay "wet" in body fluid
to survive transmission from species to species?

For example,  it might move from the blood of an infected bird--to a
misquito, and then to a human ; thhe whole time in living body fluids. Not
exposed to the air.

Other than verbal comment s by some colleagues I've never seen any written
information about this.

That would eliminate dried modes of transmission like bird droppings serving
as vectors for flies and less common mineral gatherers on droppings like
butterflies .

Thanks for your thoughts.

Best,
Lil
----- Original Message -----
From: Michael Gochfeld <gochfeld at EOHSI.RUTGERS.EDU>
To: Bob Augustine <raugustine at tms-hq.com>; <leps-l at lists.yale.edu>;
<tils-leps-talk at yahoogroups.com>
Cc: cdcresponse at ashastd.org <cdcresponse at ASHASTD.org>; <dvbid at cdc.gov>;
<nck6 at cdc.gov>; <pbright at abcbirds.org>; <esaito at usgs.gov>; <marrap at si.edu>;
<savetheocean at yahoo.com>; <JacobsburgEEProgramssp at state.pa.us>;
<Jimsmith0212 at aol.com>; <harrypav at hotmail.com>; <twalker at ifas.ufl.edu>
Sent: Tuesday, August 12, 2003 11:34 AM
Subject: Non-avian vectors and rapid spread of WNV


> Bob Augustine (see below) provided an innovative suggestion of how a
> non-avian vector (particularly Pieris rapae) might account for the
> spread of WNV.
> I think it is important to think creatively about West Nile ecology and
> to recognize that the most interesting aspects lie outside of humans.
>
> I have believed that the gap in our knowledge of "rapid spread" may
> represent a lag between the time the virus arrives and begins to
> multiply in local avian reservoirs, and the time it is "discovered" due
> to either avian, equine, or human morbidity or mortality.
>
> Thus the rapid spread may be in artifact of our sampling and monitoring
> programs.
>
> As author of a book on Butterflies of New Jersey, and as an observer on
> the current Cabbage Butterfly population explosion (late July 2003) in
> central NJ, I have more than a passing interest in the Augustine
> proposal. I will also circulate it to the two lepidoptera list servers I
> subscribe to and see if there are other perspectives.
>
> I am grateful to Bob for pointing out the Walker paper on butterfly
> migration at Gainesville, FL.  It points to a net northward movement of
> Cabbage Butterflies in spring AT THAT SITE.   In New Jersey we do not
> think of Cabbage White's as particularly migratory (either north or
> south), BUT I WILL ASK THE LIST MEMBERS WHAT HAPPENS AT OTHER
> LOCALITIES.
>
> Also quite a few butterflies feed on bird droppings, BUT I CAN'T RECALL
> SEEING A CABBAGE WHITE AT BIRD DROPPINGS.  PERHAPS OTHER LIST MEMBERS
> HAVE A DIFFERENT EXPERIENCE.
>
> Most of the other migratory butterflies irrupt from the southwest or
> south into the northeast, which doesn't seem the right direction.  The
> Monarch, of course, has dramatic southward and westward migrations in
> Sept-Oct, which would be the right time to carry a virus from the index
> cases in the northeast----but I don't recall ever seeing a Monarch at
> bird droppings.  I'll post that question also.
>
> Dragonflies, now there's a thought.  Lots of good southward migrant
> species and mosquito eaters.
>
> Michael Gochfeld
>
>
>
>
> Bob Augustine wrote:
> >
> > A proposed new WNV vector (and other WNV observations)
> >
> > In a previous (unanswered) e-mail I suggested that we need to find
another vector that travels en-
> > masse, south to north, in June or July to explain 2002's rapid extension
of WNV concentration
> > from the Gulf coast to the upper Midwest. Since bird movements do not
match this pattern, I
> > further suggested that dragonflies, butterflies, or moths might.
> >
> > Only a few butterfly species are known to migrate at all, but more are
coming to light. In recent
> > correspondence, an article published in 2001* revealed that the
(imported) Cabbage White, Pieris
> > rapae, (said by some to now be the most abundant butterfly in North
America) sometimes has a
> > very marked late spring eruption northward. Recent postings on Internet
listservs from PA and NJ
> > report unusually high numbers of this species this year. Its association
with cabbage-also a food
> > plant of the Fall Army Worm, Spodoptera frugiperda, noted as having
invaded Ontario from MS
> > in September 1973-and this migratory pattern (most evident in the record
from 1987) lead me to
> > propose the Cabbage White as a potential WNV vector. I don't think
mosquitoes bite butterflies
> > or caterpillars, however, these butterflies are known to extract
minerals from bird droppings,
> > which may be the way they pick up the virus (if they do).
> >
> > I urge the CDC to investigate the Cabbage White as a possible West Nile
Virus vector, as well as
> > other insect pests of cruciferous plants with northward summer
movements.
> >
> > Another dot to connect in this mystery just surfaced in a posting from
NJ. As you may know,
> > catnip has been found to be 10 times as effective as a mosquito
repellent as DEET. Catnip is not
> > only among the plants Cabbage Whites are reported to be feeding on in
NJ, the poster
> > writes,"First thing in the morning the cabbages congregate on catnip,
even in the shade."
> >
> > I also wrote earlier that the CDC maps for 2002 offered no clues as to
geographical routes of
> > transmission. In the 2003 bird map, however, there is a marked tendency
for positives to cluster
> > along river valleys. This may simply be because humans concentrate in
such areas and are thus
> > more likely to find dead birds there. On the other hand, I think the
pattern is a bit too extensive to
> > be explained this way. If there is a corridor effect, I reiterate that
bird numbers (post-breeding
> > wanderers-egrets, herons etc.) are too few to support a bird vector
hypothesis. But butterflies
> > that migrate north in summer in larger numbers are also noted for taking
river valley routes in
> > doing so. If moths behave in a similar fashion, they could also account
for this pattern, flying
> > undetected at night.
> >
> > It is interesting to observe that so far in 2003 the largest number of
human WNV cases (36) is in
> > CO, not IL, LA,MS or the other places that were focal points of the last
2 years. It almost
> > appears that the disease is waning in those areas now. Perhaps immunity
develops in humans in
> > only a couple of years as it seems to have in birds in the East (and
perhaps in Europe). This would
> > be really good news.
> >
> > The spread pattern on the bird map would be easier to see if more
counties did testing. This year
> > it seems fewer have along the corridors than last year. The white
(untested) areas have to be
> > ignored and only the green (tested) regions provide a useful context for
the positive test results.
> >
> > *Butterfly Migrations in Florida: Seasonal Patterns and Long-Term
Changes, Thomas J. Walker,
> > U. Fla., Gainesville, Environ. Entomol. 30(6): 1052-1060 (2001)
> > http://esa.edoc.com/environ/v30n6/v30n6p1052.pdf
> >
> > Bob Augustine
> > raugustine at tms-hq.com
> > Rockville, MD
>
>
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