Transcript Lyme Disease . ppt - Equine Veterinary Services South

LYME DISEASE:
Current Trends in
Diagnosing and Treating
Horses
Mark T. Reilly, DVM, Dipl. ABVP (Equine)
Equine Affaire 12 Nov 2009
South Shore Equine Clinic & Diagnostic Center
www.southshoreequineclinic.com
781-585-2611
TICK BORNE DISEASES
LYME DISEASE
ANAPLASMOSIS
EHRLICHIOSIS
(POTOMAC HORSE FEVER)
LYME DISEASE
1975 – 51 residents from Old Lyme,
Lyme and East Haddam, CT
1982 – Willy Burdorfer, PhD
discovered slender, spirally
undulating bacteria from blacklegged
tick (Ixodes dammini -> scapularis)
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Erythema Migrans
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1983 – spirochete named
Borrelia burdorferi
1984 – First case of canine Lyme
arthritis reported
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The CDC reported that Lyme
disease accounted for 81% of
all reports of arthropodtransmitted diseases in the US
between 1986 – 1991.
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In HORSES
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2000 – “Might not be the most
prevalent equine disease you face
with your horses, but it does exist,
and can seriously impact a horse’s
health. Although documented cases
of Lyme disease in horses are
relatively rare, there are indications
that the disease is on the increase.”
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2003 – “50% of horses in the Northeast
US are positive for exposure.”
- Successful treatment of Lyme infected
horses (Oxytetracyline)
- rDNA canine vaccine success in
ponies
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2004 – “Up to 50% of adult horses in
the northeast may be infected.”
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2005 – “Lyme disease is a problem
more commonly thought to occur in
our canine and human friends.
However, it does occur (in horses)
and can have a wide range of signs
and symptoms.”
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2006 – “As many as 20% of adult horses in
certain areas of the US are infected with
Borrelia burdorferi. Many horses in
endemic areas are, or have been,
infected, which is evidenced by the fact
that 75% of horses in the Northeast and
Mid-Atlantic states already have
antibodies against the organism.”
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Human cases parallel animal cases
1982 – 523 cases
1988 – 4,507 cases
1989 – 8,552 cases
1994 – 13,043 cases
2003 – 1,503 cases in MA
2004 – 1,532 cases in MA
2005 – 23,300 cases (2,336 cases in MA)
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23,300 human cases in 2005
= 7.9 per 100,000 nationally
=31.6 per 100,000 in the ten states where
infection is most common
= 50% increase in MA (18% nationally)
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US Department of Health and Human
Services has included Lyme disease
among its prevention priorities.
Goal of reducing the overall incidence
by more than 40% in endemic areas
by 2010.
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Horses are more likely to have a higher
prevalence than humans because
ticks stay on longer.
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The chances of your horse in the
northeast being infected with Lyme
disease may be 25 times greater than
horses in other parts of the country.
Found in 44 states, Canada, Europe,
Asia, Africa, Japan, Australia
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Ixodes scapularis (“deer tick”)
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LIFE CYCLE
LARVAL
NYMPH
ADULT
Each feeding stage requires one
vertebrate blood meal for its
development
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LARVAE
–
–
–
–
–
–
Size of a grain of sand
6-legged
May & August
Need high humidity
Rarely infected
Need host for blood meal
(*Small mammals*)
– Feed for 3-5 days
– Leaf litter for
metamorphosis
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NYMPH
–
–
–
–
Size of a poppy seed
8-legged
May-August
Need host for blood
meal
– Easily undetected
– 2nd chance to become
infected
– Leaf litter for
metamorphasis
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ADULT
– Fall –> Spring when
>40 degrees
– Feed on large
mammals
– Female drops off and
lays eggs (3,000)
– ** 48 hours**
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TRANSMISSION of DISEASE
Via Salivation or Regurgitation of
tick to host
Minimum of 24 -48 hours of tick
attachment
Nymph >>> Adult stages
(50% adults infected)
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LIFE STAGES
1.
2.
3.
4.
Larvae
Nymph
Adult male
Adult female
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VAGUE & VARIABLE SIGNS:
Stiffness/lameness
Muscle tenderness
Hyperaesthesia (sensitivity)
Swollen/sore joints
Behavioral changes
– Lethargic, “grumpy”
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SIGNS MAY MIMIC OTHER
DISEASES
Aches, fatigue – viral infection
Joint pain – arthritis
Weakness – neuro diseases (EPM)
Muscle soreness – tying up
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A DIFFICULT DIAGNOSIS
Most common complaint: “OFF”
Often no history of tick infestation OR
may take a few weeks to develop
clinical signs after tick bite
May be episodic OR chronic
Forelimbs, Hindlimbs, Pelvis
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DIAGNOSIS
Submission of infected tick
Blood Tests
– IFA antibody
– ELISA (Kela)
– Western Blot
– C6 antibody ELISA
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ANTIBODY TESTS
IFA
– patient’s serum placed on antigencoated slide and then add anti-body
conjugate
– Titer – must be interpreted
– Whole-cell method
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ANTIBODY TESTS
ELISA (Kela units)
– IgG level reported
– Chronic infection
– <130 or >380
– Whole-cell method
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ANTIBODY TESTS
WESTERN BLOT
– Need all 4 Bands = specific markers
– 4 day test
– $$$
– Whole cell method
– Inconclusive results
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ANTIBODY TESTS
C6 ANTIBODY TEST
– 3 weeks post-infection
– 100% consistent with Western Blot
– C6 Peptide is highly specific & ONLY present
during LIVE infection
– Declines rapidly and significantly after
successful therapy
– Highly sensitive & specific
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ANTIBODY TESTS
C6 ANTIBODY (SNAP TEST)
– 164 samples tested (6 had been vaccinated)
WB: 106 positive
SNAP: 109 positive
(1 negative and 2 had 1:64 low titer on IFA)
- 100% sensitive (able to find)
- 95% specific (truly infected)
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ANTIBODY TESTS
C6 ANTIBODY
TEST
– Variable region on
the spirochete
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4 DX SNAP TEST
8 minutes
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TREATMENT
ANTIBIOTICS
NSAIDs
CHONDROPROTECTIVE AGENTS
PROBIOTICS
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ANTIBIOTICS
Study done at Cornell
- Doxycycline orally – 25-50% effective
- Naxcel IM – 25 % effective
- Oxytetracycline IV – 100% effective
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OXYTETRACYLCINE
IV daily for 3 weeks
Superior to oral Doxy and IM
Naxcel
Retest at 60 post treatment
C6 Antibody tests dropped by
at least 50%; if not
completely
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Other Antibiotics:
(Doxy & Naxcel)
Rise in titers and clinical signs when
treatment is stopped in 75% of each group
Appear to inhibit reproduction, not
eradication of B.burdoferi
Doxy has anti-inflammatory effects = false
sense of improvement
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OXYTETRACYLCINE
Treatment at SSEC:
IV once daily x 5-10
days
Then switch to oral
Oxytetracycline
Powder & Probiotic
Retest at 60 days
post treatment
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OXYTETRACYLCINE
Treatment at SSEC:
896 Tested (4 years)
223 Positive
=25% infected
202 Treated
94 Retested
73 Negative (so far)
(78% success rate)
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TESTED HORSES at SSEC:
In last 15 months
335 Tested
100 Positive Lyme
=30%
Prevalence of Lyme disease
14 Positive Anaplasma
22 Both Lyme & Anaplasma
= 10% Prevalence of Anaplasmosis
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See improvement in
behavior
Attitude & Lameness
improves
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PREVENTION
rOSP canine vaccine
3 doses (day 1, 20 , 80)
Horse’s plasma has antibodies
inhibits spirochete within the tick
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PREVENTION
rOSP canine vaccine
Problems:
frequency to vaccinate?
no safety studies
questionable value once infected
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PREVENTION
Dogs
bring ticks in from woods
roll in leaves & go into tick
habitats
50% more likely to get disease
act as sentinels for disease
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PREVENTION
HORSES
Examine on daily basis (24 hours)
Neck, base of mane, ears, under tail
fine tweezers as close to skin as
possible and pull straight up
Avoid tick infested areas
Repellents with permethrins (sweat)
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White footed mouse
“the problem”
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PREVENTION
(“ the mouse”)
- Clean up brush piles
- Mow fields
- Stack wood in dry areas
- Restrict Tick migration
- Bait boxes for wild rodents with
acaracides (Field mice)
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White-tailed Deer
“the spreader”
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PREVENTION
- Do not feed deer
- Plant deer resistant plants
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White – footed mouse
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PREVENTION???
- Vaccination of white-footed mice
with canine vaccine
- Prevented the tick from the
spreading the disease to the next
host
- Measured a reduction in prevalence
of disease in nymphs
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MYTHS
No evidence of transmission directly
from animal to human
Cannot get from urine of infected
animal
Cannot get from eating a tick or
portion of mouse (in baled hay)
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1.
2.
3.
4.
5.
6.
7.
KEY POINTS
> 24 hour feeding
*** Clean up brush and debris ***
Control ticks on dog and cats
Use permethrin sprays
Good diagnostic test available
Treatable – very successfully
Re-infection always possible!
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Thank you for your attention
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Questions? Comments?
Mark T. Reilly, DVM, Dipl ABVP (Equine)
www.ssequineclinic.com
REMINDER
Upcoming client education seminars
January - March
South Shore Equine Clinic
& Diagnostic Center
www.ssequineclinic.com