Animalborne
Disease > Common
Ticks of Washington
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Dermacentor
sp. feed primarily on
rodents as sub-adults;
as adults they focus on
large mammals-deer, humans,
canids, and livestock.
Dermacentor is the vector
of the Rocky Mountain
spotted fever rickettsiae,
the tularemia bacteria,
and the toxin responsible
for tick paralysis. Distribution
appears to be statewide
in Washington. |
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Ixodes pacificus (Western
Black Legged Ticks) feed
on small rodents as sub-adults
and large mammals-deer,
canids, horses, and humans
as adults. It is the vector
for the Lyme disease spirochete,
one form of ehrlichiosis
and the babesiosis protozoa.
Distribution in Washington
appears to be primarily
in the western half of
the state. |
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Ornithodoros
sp. (soft tick) can survive
many years without a blood
meal and feeds on its
host for a short time
similar to a flea. It
is the vector for the
relapsing fever spirochete
and transmits the disease
to humans during its feeding.
Wild rodents and the tick
are reservoirs for the
disease. Trans-ovarian
transmission results in
persistent infection of
subsequent generations.
Distribution appears to
be confined to the eastern
part of the state. |
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Tick
A represents a superficial
species, such as the
American dog tick (Dermacentor
variabilis). Tick B
represents a more deeply
attached species, such
as the lone star tick
(Amblyomma americanum).
The leg bearing section
is denoted the podosoma
while the head region,
the gnathosoma.
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When
removal is attempted,
the target region for
contact with any removal
instrument should be
between the podosoma
and gnathosoma at the
basis capitulum.
The
long, central mouthpart
(called the hypostome)
is inserted in the skin.
It is covered with sharp
barbs, sometimes making
removal difficult and
time-consuming. Most
ticks secrete a cement-like
substance during feeding.
This material helps
secure their mouthparts
firmly in the flesh,
further adding to the
difficulty of removal.
It is important to continue
to pull steadily until
the tick can be eased
out of the skin.
- Avoid
handling ticks with
uncovered fingers;
use fine-point tweezers
or commercial tools
designed for removal
to grasp the tick
at the place of attachment,
as close to the skin
as possible.
- With
steady slow motion,
pull the tick away
from the skin or slide
the removal device
along the skin. Do
not jerk, crush, squeeze,
twist, or puncture
the tick.
- After
removal, place the
tick directly into
a sealable container.
- Wash
the bite site (and
your hands), disinfect
the tweezers, and
apply antiseptic to
the wound.
- Keep
the tick alive for
a month in case symptoms
of a tick-borne disease
develop. Place it
in a labeled (date,
patient) sealed bag
or vial with a lightly
moistened paper towel
then store at refrigerator
temperature.
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Tick
and Tick-borne Disease in
Washington
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Disease
and Initial Symptoms
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Tick
Genus
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Rocky
Mountain Spotted Fever
- Sudden
fever
- Headache
- Muscle
pain
- Reddish-to-black
rash
At
least 4-6 hours of attachment
and feeding on blood
by the tick are required
for the rickettsiae
to reactivate and become
infectious. Incubation
3 to about 14 days.
In Washington, one to
two cases occur each
year.
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Dermacentor

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Tick
Paralysis
- Fatigue
- Unsteady
gait
- Muscle
pain and weakness
beginning in the legs
and moving upward
- ascending paralysis
Removing
the tick removes the
source of the neurotoxin.
Recovery is rapid following
removal.
Six
cases of tick paralysis
have occurred in the
state during 1989 through
2000.
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Dermacentor
and Ixodes
 
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Tularemia
- Fever
- Headache
- Swollen
lymph nodes
- Skin
ulcer near bite
Incubation
1-14 days. Usually 3-5
days. In addition to
tick bite, transmission
can occur from contaminated
pelts, meat, or water;
inhalation of contaminated
dust; and laboratory
exposure.
Two
to four cases of tularemia
occur each year in Washington.
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Dermacentor
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Babesiosis
- Fever
- Chills
- Fatigue
- Muscle
pain
- Anemia
Incubation
variable; 1 to 8 weeks.
Recrudescence of symptoms
after prolonged asymptomatic
parasitemia may occur
months to more than
a year after initial
exposure.
Babesiosis
is rare; only two cases
have ever been reported
in Washington.
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Ixodes
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Lyme
Disease
- Fever
- Headache
- Stiff
neck or neck pain
- Fatigue
- Slowly
expanding "bull's-eye"
rash
Incubation
3 to 32 days (mean 7-10
days); erythema migrans
usually occurs 7 to
10 days after tick bite.
Transmission usually
does not occur until
tick has been attached
for 24 hours or more.
In
Washington, an average
of 15 cases occur each
year. A Guide for Washington
Physicians available
at:
http://healthlinks.washington.edu/nwcphp/lyme/
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Ixodes
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Relapsing
Fever
- Sudden
fever (?100.5°F),
chills, headache
- Muscle
and joint pain
- Vomiting
and abdominal pain
- Febrile
periods lasting 2-9
days, afebrile periods
lasting 2-4 days.
- Relapses
can number 1-10 or
more
- Petechial
rash common during
initial fever
Incubation
from 5 to 15 days; usually
8 days.
Four
to eight cases of relapsing
fever occur each year
in Washington.
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Ornithodoros
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Last
Updated
Friday, August 29, 2008 3:56 PM
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