West Nile virus, birds, migratory - USA (02) (fwd)

'Devorah' D Wisti nyneve at u.washington.edu
Sat Sep 14 09:06:21 PDT 2002


more on west nile virus, for those who are interested.

regards,

Devorah A. N. Bennu, PhD Candidate    email:nyneve at u.washington.edu
Department of Zoology, University of Washington, Seattle, Wash, USA
         After September 2002: Chapman Postdoctoral Fellow
       The American Museum of Natural History, New York City
   Visit me on the web: http://students.washington.edu/~nyneve/
           Love the creator? Then protect the creation.

---------- Forwarded message ----------
Date: Fri, 13 Sep 2002 22:42:24 -0400 (EDT)

WEST NILE VIRUS, BIRDS, MIGRATORY - USA (02)
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[1]
Date: Fri, 13 Sep 2002 07:41:30 -0500
From: Alan Wheeler <Alan.Wheeler at gov.ky>


Bird migration is not just a seasonal north-south movement. Many ducks like
scooters will nest in the interior of the province and merely move to the
coast for the winter, performing an east-west migration.

--
Alan Wheeler
<Alan.Wheeler at gov.ky>

******
[2]
Date: Fri, 13 Sep 2002 08:45:56 -0400
From: Dickson Despommier <ddd1 at columbia.edu>


It seems much more likely to me that the WNV spread from East to West via
the major highway systems (Routes 80, 95, etc.) than by any infected
migratory bird population. The drafts of automobiles and trucks along all
the major roadways, each one of which is lined with drainage ditches filled
with polluted, stagnant water, the perfect habitat for _C. pipiens_, could
easily account for distributing infected mosquito pools to new locations,
where they then could then bite crows and other roadside feeding birds
(crows, blue jays, etc.).

Trains could also help with distribution of mosquitoes. Infected birds
could then carry the virus to the next roadside venue, continuing the cycle
in mosquito populations breeding in these right-of-way ecotones.

I believe in this way the WNV hop-scotched across the country without the
aid of migratory birds.

--
Dickson Despommier
Columbia University
School of Public Health
<ddd1 at columbia.edu>

******
[3]
Date: Fri, 13 Sep 2002 08:27:13 -0700
From: Centre for Coastal Health <CCH at MALA.BC.CA>


When considering the idea of birds moving West Nile virus around North
America, it is important to think of animal movements in a broader sense
than just in terms of the major north-south flyways. There are a number of
birds that move east-west as part of seasonal movement from breeding
grounds to foraging areas. For example, some waterfowl move from the
Prairie province to British Columbia on the west coast of Canada each year.

Moreover, there are "straying birds" that move east-west. There are records
of songbirds being banded in eastern USA being found in western Canada.
Finally, there are some species that are expanding westward, such as the
incursion of blue jays from eastern to western Canada. We may also need to
consider the trade in pet birds and the movement of wildlife by
well-meaning but misinformed folks.

There are 2 critical questions to consider in these deliberations.

First, What is the capacity of an infected bird to survive long enough to
transport the virus and allow its transmission to local hosts?

Second, How many infected birds need to move to an area to establish a
endemic focus? Do we need to see a mass migration of several birds or will
the movement of one infected bird into a region be sufficient? The latter
question is important to consider if one is planning surveillance
techniques, especially in regions that are, to date, West Nile-negative.

--
Craig Stephen DVM PhD
Centre for Coastal Health
UBC Centre for Disease Control
Nanaimo, British Columbia
Canada

[Threshold theory would suggest that it would be rare for a single viremic
bird to achieve a successful and productive virus transfer. Similarly, how
many infected mosquitoes have to be transported in this way to set up a new
focus? - Mod.MHJ]

******
[4]
Date: Thu 12 Sep 2002 11:08 PM
From: Stephen M. Apatow <s.m.apatow at humanitarian.net>


This is a discussion I had with USGS/APHIS in 1999.  Major challenges
existed just after the initial outbreak in New York City due to the
administration change.  I brought up the topic of research of bird
migration patterns and the potential geographic spread from the
onset.  Since we were not in a crisis, our progress was limited and no one
seemed to take the threat seriously.

I have maintained a West Nile Virus web site on my Emerging Infectious
Disease Network since 1999:
<http://www.humanitarian.net/eidnet/wnv>

A couple of resources that specifically address this issue and might serve
as a starting point, are as follows:

Migratory Birds and Spread of West Nile Virus in the Western Hemisphere
John H. Rappole, Scott R. Derrickson, and Zdenek Hubalek
<http://www.cdc.gov/ncidod/eid/vol6no4/rappole.htm>

USGS: Migration of Birds: Routes of Migration
<http://www.npwrc.usgs.gov/resource/othrdata/migratio/routes.htm>

The rapid spread of West Nile Virus throughout North America represents a
significant reference point for the potential geographic impact of a
bioterrorist incident.

--
Stephen M. Apatow
Humanitarian Resource Institute
Biodefense Reference Library
Internet: <http://www.humanitarian.net/biodefense>
Email: <s.m.apatow at humanitarian.net>

[Both well worth reading. The first deals solely with New England and in
retrospect raises a question as to why we have yet to see reports of WNV in
the southern receiver areas in Central and South America for the birds
tracked. The second covers a wide range of migrating species from across
North America. - Mod.MHJ]

******
[5]
Date: Fri, 13 Sep 2002 11:50:52 -0400
From: Dr. Joseph Dudley ACSIM/Versar <Joseph.Dudley at hqda.army.mil>


Your hypothesis of east-to-west movement by containers does not seem to fit
the observed pattern and timing of the spread and proliferation of West
Nile Virus.

Were freight and/or container shipments a major driver of WNV
proliferation, I believe there should have been a more stochastic,
randomized distribution of WNV in humans as well as animals throughout the
US and southern Canada during 2000 and 2001. Given the frequency and speed
of cross-continental freight shipments, WNV should have shown up long ago
in major cities all along the West Coast, were this disease being moved
around principally via container traffic.  [Good point. - Mod.MHJ]

The observed timing and pacing of dispersal of  WNV appears entirely
consistent with initial dispersal into the Florida and the eastern Gulf
Coastal Plain by southward migrating birds in 1999 and 2000, and subsequent
redistribution and proliferation northward and westward by migrants
infected on wintering and summering grounds since that time. The available
evidence seems consistent with the hypothesis that initial spread within
the middle Atlantic Coastal Plain during 1999 was mediated primarily by
crows, and that the subsequent explosive dispersal has been the result of
progressive epidemic infections of a broad suite of migratory passerines on
wintering grounds in the Gulf Coastal region of the southeastern USA during
the winters of 2000 and 2001.

The Los Angeles CA case recorded this year may simply be an aberrant and
isolated -- albeit not unexpected -- instance of "airport import".
Alternatively, it may be the result of the translocations of infected
captive bird(s) from the East Coast through the pet trade or as the result
of a household relocation.

--
Joseph P. Dudley, Ph.D.
Conservation Specialist
Office of the Director of Environmental Programs
Pentagon
<joseph.dudley at hqda.army.mil>
Research Associate
Versar, Inc.
Institute of Arctic Biology, University of Alaska Fairbanks
Dept of earth Sciences, Univerity of Alaska Museum

[Joseph makes a number of telling points. However, one aspect to keep in
mind is that the receiver site must be mosquito-friendly. My daughter, who
lives in LA, tells me that their mosquito populations are so low that dogs
and cats do not need to be treated with heartworm preventatives. This will
not be true everywhere in Southern California, nor for all potential vector
species. - Mod.MHJ]

[I do not believe the east-west duck movements in Canada are relevant.
Since British Columbia lies mostly west of the Rocky Mountains, I doubt
that the ducks moving from the interior of the province to the coast are
crossing them, which is what is needed for transport from the eastern USA
to California and the states west of the mountains. - Mod.JW]
................................mhj/cp/pg/dk




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