| Epizootic
Hemorrhagic Fever |
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| Causative Agent |
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Epizootic
Hemorrhagic Disease (EHD) is a viral
disease of wild
ungulates caused by
viruses of the genus Orbivirus.
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Bluetongue, a viral disease
of wild
ungulates caused by another
Orbivirus, has similar signs and symptoms.
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The diseases caused by both
Bluetongue and EHD are collectively known as
hemorrhagic disease.
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| Images |
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Click on
image to
enlarge. |
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Hemorrhage in the eyes of a
white-tailed deer infected with EHD. |
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| Distribution |
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Geographic: |
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EHD is widely distributed in both temperate and tropical regions of the
world, but in free-ranging wildlife has only been reported in North America.
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In BC, it has been reported in bighorn sheep (Ovis
canadensis) and white-tailed deer (Odocoileus
virginianus) in the Okanagan Valley.
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Seasonality: |
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EHD occurs in late summer and early fall. This is thought to be related
to seasonal wind patterns moving the insect
vector northwards from
endemic areas in the USA.
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| Hosts and Transmission |
| Hosts: |
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Primarily white-tailed deer and mule deer (Odocoileus hemionus); less frequently elk, pronghorn antelope and
bighorn sheep.
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Severity of EHD is quite variable and may be related to herd
immunity.
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Transmission: |
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EHD is transmitted by various species of Culicoides midges (commonly
called no-see-ums).
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The
virus enters the blood of hosts
from the midge. In some species,
viral replication may occur in
the walls of blood vessels.
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Blood vessels are damaged
leading to numerous small and large
hemorrhages - hence, the
hemorrhagic nature of this disease.
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| Signs and Symptoms |
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Signs are variable, ranging from none to sudden death.
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Sick and dead animals are often found near water.
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Other signs include:
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swelling of the face,
tongue, neck and
conjunctiva of the eyes;
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lack of appetite;
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weakness and incoordination;
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excessive salivation, often
blood-tinged;
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nasal discharge, often
blood-tinged;
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bloody diarrhea;
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lameness;
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extensive
hemorrhaging in many tissues including
the skin,
gastrointestinal tract, heart, testicles;
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ulcers in the tissues of the
mouth, tongue and stomach;
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breathing difficulty;
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recumbancy (lying down);
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overgrown/cracked hooves.
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| Meat Edible? |
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EHD does not infect humans, and eating venison from deer with EHD is not
dangerous; however, secondary infections that may occur as the
disease progresses can render venison unfit for consumption.
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The meat should not be fed to dogs.
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| Human Health Concerns and
Risk Reduction |
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EHD
virus is not associated with
human disease.
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| Samples for Diagnosis |
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The whole body should be submitted for post mortem.
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Immunological tests can verify if EHD
virus is present in the following
tissues, which should be REFRIGERATED
NOT FROZEN:
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blood collected with
anti-coagulant and the spleen (best);
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lymph node, lung or bone marrow.
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| Further Reading |
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