Wildlife
Health Issues in Washington State
By Briggs Hall DVM, and Kristin Mansfield DVM
| Sage
grouse may be threatened by West Nile virus.
Photo: WDFW |
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Black-tailed
deer hair loss syndrome
A definitive diagnosis as to the underlying cause of the hair
loss syndrome in black-tailed deer may be near. Dr. James Mertins,
an entomologist with the USDA’s Animal and Plant Health
Inspection Service, has identified the lice which are causing
west side black-tailed deer to rub, chew, and lick their hair
out, as Damalina cervicola, an exotic (non-native) species.
Early
on it was evident that hair loss deer were suffering from
an intense dermatitis caused by large numbers of biting lice.
Previously parasitologists identified the lice as Damalina
bovicola, the common and native deer louse. Whereas lice are
not uncommon on black- tailed deer, it is believed that louse
numbers only increase to harmful levels when the deer’s
immune system becomes stressed by nutritional deficiencies,
debilitating disease processes, or heavy internal parasite
loads. Our attempt to identify this unknown stressor has been
the focus of our research.
Damalina
cervicola is a louse historically found on old world ungulate
hosts. According to Dr. Mertins, D. cervicola was first recognized
in southeastern United States fourteen years ago. D. cervicola
may have entered Washington in conjunction with the influx
of large numbers of exotic deer in the 1980’s. According
to biologists, a new parasitic species will be much more damaging
to a host than a similar parasite with which the host has
been associated for centuries.
We are
continuing to submit lice collected from hair loss deer residing
in various locations around western Washington. If we continue
to extract the exotic louse (D. cervicola) from the deer suffering
from hair loss syndrome, we may soon be able to say with confidence
that the exotic louse is the cause of the black-tailed deer
hair loss syndrome.
West
Nile Virus
Working in conjunction with the Washington State Departments
of Health and Agriculture, the Department of Fish and Wildlife
was braced for the serious epidemic of West Nile virus infection
that was anticipated last summer. To the dismay of epidemiologist
and the delight of everyone else, the expected epidemic did
not materialize. With the arrival of mosquito season we are
again vigilant for signs of West Nile virus infection.
The West
Nile virus belongs to a group of viruses known to cause encephalitis,
a potentially fatal inflammation of the brain and spinal cord.
The West Nile virus is known to primarily affect birds, horses
and humans. Mortalities in other species have been documented.
Of major concern to the Department of Wildlife are the reports
of mortalities from West Nile virus in sage grouse in Wyoming,
Montana and Alberta. In 2003, a total of 27 sage grouse were
confirmed to have died from West Nile virus; 19 in Wyoming,
3 Montana and 5 Alberta, Canada. They were found by researchers
tracking radio-collared sage grouse on four different studies.
This is a brand new issue in sage grouse conservation and
the effect that West Nile virus will have on sage grouse populations
across their range is not yet known. Surveillance efforts
conduced by the National Wildlife Health Center revealed West
Nile virus in doves, pigeons, pheasants, wild turkey, ruffed
grouse, mallard and Canada geese. To what extent the populations
of these species are being impacted is unclear at this time.
Avian
Influenza
The recent outbreak of Avian Influenza in British Columbia
is cause for great concern to the poultry industry. Many wild
bird species may be infected with the avian influenza viruses.
The virus is often found in waterfowl. Virulent viruses that
cause serious disease in domestic fowl do not cause disease
in waterfowl. Likewise avian influenza viruses do generally
not affect upland birds. |
