- Local hunting and fishing gets so busy this time of year,
it's easy to ignore what's going on elsewhere. Sometimes, though, news
brings a shudder of recognition. A few years ago, a productive deer hunting
spot in Nebraska suddenly came up virtually deer-less.
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- Where we'd seen pretty good numbers of mature bucks and
big does, we were mostly seeing lone fawns. First one hunter, then another,
reported seeing an adult deer running with its lips rolled back, a spot
or 2 of blood visible. Several of us caught the sickening odor of a decaying
animal down near a marsh edge.
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- Epizootic hemorrhagic disease (EHD), we would learn,
had pretty much wiped out our hunting spot. Spread by tiny flying insects
called biting midges, EHD causes severe, flu-like symptoms in deer.
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- High fever sends deer toward water for relief, and that's
often where they die, often less than 3 days after becoming infected. Cattle
can suffer from it, but dogs and cats don't get it. EHD does not appear
to affect humans, but hunters are always urged to avoid contact with sick
animals. If deer survive the infection, they often have cracked hooves
or heavy hoof overgrowth.
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- A hard frost is said to kill off biting midges, ending
that year's outbreak. Whitetail populations recover, but it can take years.
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- This year, a news release reported EHD in west-central
Indiana. Up to 30 EHD-killed deer were found there.
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- Then, a week or so ago, Michigan's DNR and Michigan State
University's Diagnostic Center for Population and Animal Health confirmed
2 Allegan County deer infected with EHD. Their carcasses were among about
50 dead deer found along southwest Lower Michigan rivers and marshes. One
was a free-ranging deer and 1 was privately owned.
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- Bill Moritz, chief of the DNR's wildlife division, said
Michigan seldom gets hit with EHD, which he said is considered the most
important viral disease facing whitetails nationwide. It last struck here
in 1955 and 1974. "When all conditions are right -- weather, virus
and host -- the disease may occur," he said in a news release.
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- We're not alone. So far this year, besides Indiana, EHD
has been diagnosed in Oregon, Wyoming, Texas, Missouri, Illinois and Georgia.
If you find a dead deer near water, or if you shoot one with unusual hoof
growth or hoof damage, contact the nearest DNR office (Bay City, Sanford
or Gladwin, for most of us), or visit the DNR website at <http://www.michigan.gov/dnr>.
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- http://www.ourmidland.com/site/printerFriendly.cfm?brd=2289&dept_id=472541&newsid=17317931
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- ProMed -
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- EHD is not uncommon in many states. EHD is an acute,
infectious, often fatal viral disease of some wild ruminants. This malady,
characterized by extensive hemorrhages, has been responsible for significant
epizootics in deer in the northern United States and southern Canada. A
similar hemorrhagic disease called bluetongue also occurs in wild ruminants.
The 2 diseases are antigenically different, although there are similar
clinical signs.
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- The first occurrence and subsequent identification of
EHD occurred in 1955, when several hundred white-tailed deer (_Odocoileus
virginianus_) succumbed in both New Jersey and in Michigan. It was considered
a new disease of deer, and the name "epizootic hemorrhagic disease"
was suggested to describe its main clinical and pathological features.
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- Since the initial 1955 outbreak, this malady has occurred
primarily among white-tailed deer, although occasionally mule deer (_O.
hemionus_) and pronghorn antelope (_Antilocapra americana_) have also succumbed.
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- The mode of transmission of EHD in nature is via a _Culicoides_
biting fly or gnat. _Culicoides variipennis_ is the most commonly incriminated
vector in North America. A common observation in outbreaks involving large
numbers of deer (as in Michigan, New Jersey, and Alberta) is that they
are single epizootics that do not recur. Die-offs involving small numbers
of deer (as experienced in South Dakota and Nebraska) occur almost annually,
and the disease appears to be enzootic in these areas. All documented outbreaks
of EHD have occurred during late summer and early fall (August-October)
and have ceased abruptly with the onset of frost.
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- Clinical signs of EHD and bluetongue are similar. White-tailed
deer develop signs of illness about 7 days after exposure. A consistent
characteristic of the disease is its sudden onset. Deer initially lose
their appetite and fear of man, grow progressively weaker, often salivate
excessively, develop rapid pulse and respiration, and finally become unconscious.
Hemorrhage and lack of oxygen in the blood result in a blue appearance
of the oral mucosa, hence the name "bluetongue". Between 8 and
36 hours following the onset of observable signs, deer pass into a shock-like
state, become prostrate, and die.
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- The gross and histological lesions of EHD are characterized
by extensive hemorrhage, ranging from pin-point to massive in size, and
involve different tissues and organs in individual animals. No organs appear
to be exempt from hemorrhage, with the most regularly involved being the
heart, liver, spleen, kidney, lung, and intestinal tract. Extensive hemorrhaging
is the result of interference with the blood-clotting mechanism together
with degeneration of blood vessel walls.
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- Because of its very high mortality rate, EHD can have
a significant effect upon the deer population in a given area, reducing
numbers drastically. Hemorrhagic disease can be transmitted to other wild
ruminants. The EHD virus can infect domestic animals but rarely causes
disease. Presently there is no evidence that the virus crosses into humans.
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- Portions extracted from Roselake Wildlife Disease Laboratory
site: http://www.dnr.state.mi.us/wildlife/Division/RoseLake/Publications/Disease_Manual/ehd.html
-
- - Mod.TG
-
- Patricia A. Doyle DVM, PhD
- Bus Admin, Tropical Agricultural Economics
- Univ of West Indies
-
- Please visit my "Emerging Diseases" message
board at:
- http://www.emergingdisease.org/phpbb/index.php
- Also my new website:
- http://drpdoyle.tripod.com/
- Zhan le Devlesa tai sastimasa
- Go with God and in Good Health
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