September 2023 - 22

HEMORRHAGIC DISEASES
It's well known that mule deer face many
challenges. Not only do they endure the natural
weather patterns of Wyoming, they also
endure cyclic disease patterns. Hemorrhagic
diseases is a general term for illnesses caused
by two related viruses - epizootic hemorrhagic
disease and bluetongue virus. These diseases
are viral in origin and can wreak havoc on a herd.
Hemorrhagic diseases are transmitted to deer
through the bite of an infected midge. These
naturally occurring diseases typically result in
isolated outbreaks, with major outbreaks occurring
in cyclic patterns every 4-7 years.
Deaths from EHD and BTV are not uncommon
in times of drought and hot weather, especially
where wildlife congregate around small watering
holes where the disease-carrying, biting midges
are active. Wyoming's wildlife managers see EHD
and BTV in deer every year. However, some years
have greater impacts than others. In 2021 the
state saw significant losses of deer and pronghorn,
especially in the eastern half of the state.
There are no known treatments or control
methods for the disease in wildlife. However,
there is a silver lining. Data suggests neither
EHD or BTV negatively impacts population
stability or limits population growth in the long
run, but can trigger short-term and visible population
impacts.
" The disease impact in Wyoming isn't as
severe as some areas of the United States,
although in localized outbreaks we may see
mortalities in up to 25 percent of the herd, "
said Samantha Allen, state wildlife veterinarian.
In Wyoming and the Rocky Mountain West,
animals are often found dead without any
evidence or history of illness. In an effort to
help further understand the disease and distribution
across the state, wildlife managers
request the public's help and encourage them
to report deer displaying any clinical signs to
their regional Wyoming Game and Fish Department
office. Clinical signs vary from rapid
death to lingering effects such as deformed
hooves or poor body condition. Deer infected
with these diseases may experience fever,
inability or unwillingness to move, respiratory
distress, noticeable swelling of the head or
neck and may have foam observed around
the mouth/nose.
This fall hunters should be aware of these
diseases, but shouldn't be concerned about
contracting EHD/BTV or spreading it to their
dogs. Humans are not at risk of contracting
the diseases. Game and Fish monitors
the extent of the diseases across the state
through an interactive map found online.
- Breanna Ball
Scan this QR code to
view the prevalence of
hemorrhagic disease
across Wyoming.
department, " said Doug Brimeyer, Game
and Fish deputy chief of wildlife. " As wildlife
managers, it is incumbent upon us to
continue to monitor the disease and evaluate
future management actions. "
Wildlife managers know a lot about mule
deer and what impacts their overall success
from decades of research and data. Managers
have spent years researching how habitat and
weather patterns affect deer populations.
They have committed millions of dollars
toward habitat restoration and providing
deer with the support they need to become
resilient. The same is true for the surveillance
and management of CWD. For the
last 10 years, Game and Fish has spent $4.5
million to learn more about the disease and
what it means for the future of Wyoming's
mule deer.
" We know a lot about deer, and while
CWD has been in Wyoming for decades,
we still have a lot to learn about managing
the disease in herds where it is established
and where it has been recently detected, "
Brimeyer said.
22 | September 2023
The data collected so far demonstrates this
disease can have population-limiting effects
in areas where prevalence is high by lowering
adult survival rates and destabilizing longterm
population dynamics.
Keaton Weber, Game and Fish wildlife
biologist in Wheatland, is tasked with monitoring
the Laramie Mountains mule deer
herd. Wildlife managers in this area have
witnessed high CWD prevalence over the
last 20 years and documented a decline in
the local mule deer population. Prevalence
within this herd is currently 18 percent, but
historically it has experienced some of the
highest prevalence in the state.
" High CWD prevalence over the longterm
has certainly had an impact on the
viability and productivity of our mule deer
herd, " Weber said. " Tooth-age data correlated
with CWD results shows prevalence
is highest within mature males of the population
and we certainly see that reflected in
our aerial classification flights and harvest
data. We simply don't have many older-aged
males within this population. "
https://wgfd.maps.arcgis.com/apps/webappviewer/index.html?id=b8aee93bc9e64143b5f377cdd0012e5d
September 2023

Table of Contents for the Digital Edition of September 2023
