[wisb] UW Vet school West Nile virus research, robins

From: "msmith112 tds.net" <msmith112@xxxxxxx>
To: iltlawas@xxxxxxxxxxxxx
Date: Sat, 25 Jul 2009 17:47:48 -0500
Do Chicago?s suburbs hold the key to understanding West Nile virus?
July 22, 2009

by Terry Devitt <%74%72%64%65%76%69%74%74@%77%69%73%63.%65%64%75>

When Tony Goldberg <http://www.vetmed.wisc.edu/goldberglab/> is not whacking
through the brush of central Africa, one of the world's great cauldrons of
emerging human and animal disease, he is scouring another disease hot spot:
the southwestern suburbs of Chicago.

In places such as the Chicago suburb of Oak Lawn, the American robin seems
to be a key player in the spread of West Nile virus, a serious pathogen that
infects mosquitoes, birds and humans.

Photo: courtesy Gabe Hamer, UW-Madison

For Goldberg, an epidemiologist and a professor at the UW-Madison's School
of Veterinary Medicine <http://www.vetmed.wisc.edu/>, the Chicago suburbs
near Oak Lawn are the perfect laboratory for prying loose the secrets of
West Nile virus, a pathogen carried by mosquitoes and birds that infects and
sickens thousands of people each summer.

"A characteristic of West Nile virus is that it often affects people in
urban and suburban settings," says Goldberg of a virus that, as its name
implies, has its origins in the Old World of Africa and the Middle East.
"But the pattern of disease across the urban landscape isn't uniform. It is
more common in some places than others."

And Chicago ? especially its suburbs like Oak Lawn, Goldberg says ? seems to
harbor the perfect combination of factors to give the virus an
epidemiological leg up. "Chicago is one of the cities most affected by West
Nile virus," says Goldberg, whose research group is scouring the lawns and
thickets of Oak Lawn and surrounding areas in search of the reservoirs of
disease.

The goal of Goldberg?s study is to ferret out the reasons why one
neighborhood might be in the eye of the West Nile storm while another
neighboring area is not.

In the case of West Nile, the key players are mosquitoes and birds, which
carry the virus that can cause potentially fatal encephalitis or meningitis
in humans, according to Gabe Hamer, a UW-Madison postdoctoral fellow
who is leading
the field effort <http://www.vetmed.wisc.edu/WNV/> in Oak Lawn. The disease
is spread to people through the bite of the mosquito, which becomes infected
by feeding on birds that carry the virus.

"It was found early in the discovery of West Nile virus in North America
that certain bird species seemed to be important," Goldberg explains, noting
that larger birds such as crows and blue jays seemed to be especially prone
to infection. "It turns out that they are very susceptible to the virus, but
they are not the most important species for amplifying the disease. In
Chicago, there is one bird species that stands out above all others as a
driver of West Nile amplification: the robin. It is the indisputable super
spreader of the virus in the Chicago region."

In particular, says Goldberg, whose group is identifying blood meals of
mosquitoes and using radio telemetry by mounting transmitters to robins to
study their movements, it is young, recently fledged robins that seem to be
the ideal hosts for the pathogen. "While they carry the virus, they seem to
be more resistant to the disease than other birds, there are lots of them
and they seem to be good at transmitting West Nile at just the right time of
year," he says, noting that crows and jays typically die not long after
infection.

Fat with blood, the mosquito species Culex pipiens is the primary vector of
West Nile virus in the American midwest.

Photo: courtesy Gabe Hamer, UW-Madison

Because robins can sustain the virus, they become a key reservoir of the
pathogen, infecting the mosquitoes that feed on them and amplifying the
cycle of infection, says Hamer.

The curious epidemiological puzzle of West Nile is that while some places in
suburban Chicago seem to be hot spots for the disease, similar environments
across the North American landscape have a much lower incidence of the
disease.

"We see variation among cities and within cities," says Goldberg, explaining
that cities such as Atlanta and Madison have many of the same environmental
attributes and species affected by West Nile, but see much lower incidence
of disease in people. "We see flare-ups in certain environments, but not in
similar environments, or even in similar environments near a hot spot."

The goal of Goldberg's study is to ferret out the reasons why one
neighborhood might be in the eye of the West Nile storm while another
neighboring area is not. "We are comparing adjacent neighborhoods a few
kilometers apart, which is a finer scale in urban environments than anyone
has studied before," he says.

An American robin is fitted with a radio tag in the Chicago suburb of Oak
Lawn. Researchers are tracking the birds in an effort to understand why West
Nile occurs more often in some locales than others.

Photo: courtesy Gabe Hamer, UW-Madison

His group, which includes teams of students, postdoctoral researchers and
collaborators from the University of Illinois, Michigan State University and
Emory University, is tracking the movements of robins using radio
transmitters and searching for their hidden nighttime roosts. They are also
recording climate and weather data, as well as local patterns of vegetation,
in an effort to tease out the factors that contribute to disease.

Next year, Goldberg, with the help of a group led by Ned
Walker<http://www.ent.msu.edu/FacultyPages/walker/tabid/140/Default.aspx>of
Michigan State University, hopes to track the movement of mosquitoes
across the suburban landscape using chemical isotopes found in the insects,
which can pinpoint where they hatched.

The idea, says the Wisconsin researcher, is to identify the factors that
cause a flare-up of disease at a particular place in time.

"If you can find those places and the reasons why disease occurs in one
place and not another, that points to obvious avenues for intervention and
disease prevention," argues Goldberg.
The study is funded by the National Science Foundation and the National
Institutes of Health through their joint program in Ecology of Infectious
Disease <http://www.nsf.gov/funding/pgm_summ.jsp?pims_idR69>

On 7/25/09, William Mueller <iltlawas@xxxxxxxxxxxxx> wrote:
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[wisb] UW Vet school West Nile virus research, robins

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