4/27/2012
Ticks and Tick-borne Diseases:
More than just Lyme
http://www.scalibor-usa.com/tick-identifier/
Katherine Sayler and A. Rick Alleman
Important Emerging Pathogens
Increase in disease prevalence in
pets and people
Perceived emergence in pets
Positive control
Better diagnostic capabilities Anaplasma
Ehrlichia
Lyme
True emergence
Increase and spread of tick vectors
and wildlife reservoirs
Housing developments in rural areas
The Importance of the Veterinarian
We are aware of and equipped
to diagnose vector-borne
disease and/or exposure to
vector-borne pathogens in pets
Educate owners of ppets
exposed to vector-borne
pathogens
Positive control
Anaplasma
Ehrlichia
Lyme
Many are zoonotic pathogens
Dogs are sentinels for human
exposure
People and pets have similar
environmental exposure
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4/27/2012
Tick-Borne Pathogens
Expert evaders of the host immune system
Rapid antigenic variation
Nidus of infection in various host tissues
Chronic, persistent infections in people and pets
Chronic, vague illnesses affecting various organ
systems
Vector-Borne Diseases are
Often Misdiagnosed
Many people we have encountered with vectorborne disease have chronic history of vague, often
severe illnesses
Multiple sclerosis
Neuropathies (Guillain-Barre Syndrome)
Joint disease (RA)
Nephropathies
Chronic fatigue syndrome
Various immune-mediated disorders (SLE)
What can veterinarians do?
Get acquainted with your local public health
personnel
Maybe some are clients?
Local physicians sensitive to the presence of vectorborne diseases
One Health Initiative – zoonotic diseases
Organization that promotes cooperation between
various health professions
Promote public awareness through public seminars
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How often do ticks carry these
bad bugs?
Ixodes scapularis ticks collected over a fourstate area (IN, ME, PA, WI)
89% of ticks infected with one or more
pathogens
p
g
(Anaplasma,
(
p
Babesia, Borrelia))
55% of the infected ticks carried a single infectious
agent
45% carried two or more infectious agents
37% contained two infectious agents and 8%
contained three pathogens
(Steiner FE, et al. J Med Entomol 2008. 45(2)289-297)
Current project (Florida tick population)
Which agents are likely to be involved?
Most tick species can transmit more than one agent
Ixodes spp. (deer tick): Anaplasma phagocytophilum
and Borrelia burgdorferi
Amblyomma americanum (Lone star tick): Ehrlichia
chaffeensis and E.
E ewingii,
ewingii B.
B lonstari,
lonstari R.
R rickettsii
R. sanguineus (brown dog tick): E. canis, A. platys, R.
rickettsii
Agents that can be transmitted by multiple arthropod
vectors
Bartonella spp.
Ixodes scapularis (east) and
Ixodes pacificus (west)
Black-legged tick or
deer tick
I. scapularis: Eastern
coast of the United
States as far north as
Maine, spreading
westward to Iowa
Florida to central Texas
forms the lower
boundary
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Important Pathogens
Borrelia burgdorferi
Lyme disease
Anaplasma phagocytophilum
Granulocytic anaplasmosis
Prevalence of Lyme: Humans
Reported in all 48
states in U.S. mainland
Alaska and Hawaii
Eastern and western
coastal states
Upper Midwest
Distribution coincides
with activity of deer
tick
Prevalence: Canines
Reported in all 48
states in U.S. mainland
Eastern and western
coastal states
Upper Midwest
Distribution coincides
with activity of deer
tick
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Prevalence of infection with A. phagocytophilum
Defining Infection with
Anaplasma phagocytophilum
Anaplasma phagocytophilum
Tick-transmitted, obligate
intracellular bacterium
Causative agent of
granulocytic anaplasmosis
Can infect a wide variety
of hosts
Humans, dogs, cats, horses,
ruminants
Deer, rodents, and other
wildlife (mountain lion,
coyote and black bear)
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Clinical Signs in Dogs
Golden and Labrador retrievers over-represented
Three separate studies by Greig 1996, Egenvall 1997
and Beall et al. 2008 (Vector Borne Zoonotic Disease)
Breed popularity vs. susceptibility
Vague clinical signs of illness
Fever, lethargy, anorexia, muscle pain, reluctance to
move
Lameness and joint pain – inflammatory
polyarthritis
Indistinguishable from Lyme disease and E. ewingii
Meningitis
Gastrointestinal signs
Respiratory signs (pneumonitis)
Morulae in Peripheral Blood
or Synovial fluid
Microscopic
identification of
morulae
Usually seen during
acute phase of the
disease (1 to 10 wks
PI)
1% - 20% of
circulating neutrophils
Synovial Fluid Analysis
Important in dogs with
clinical evidence of joint
disease
Intracytoplasmic morulae
in neutrophils (1% to 10%)
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Western Immunblot Assay
Horses, dogs,
humans and cattle
infected with A.
phagocytophilum
were
ere tested
Antigen: A. phagocytophilum/ endothelial cell culture
100
50
37
*Dumler et al. 1995 J Clin
Microbiol 33:1098-1103
All sera tested
reacted with 44
kDa antigen
25
15
Human anti-AP
Canine anti-AP
SNAP® 4Dx® (IDEXX Laboratories Inc.)
Uses synthetic peptides
based on a conserved
region of the p44 (Msp2)
antigen
Experimentally, dogs
seropositive
se
opos t ve by 8 days PI,,
throughout 340 day trial
period
Positive control
Anaplasma
E. canis
L
Lyme
*Alleman et al. 2006, J Vet
Intern Med 20:763
Recognized high
seropositivity in healthy
dogs (some places >40%)
Therapy
Doxycycline drug of choice
Optimal dose and length of
therapy not firmly established
Current recommendation
5 mg/kg BID, for 30 days
Rifampin and levofloxacin in
vitro
* Maurin et al., 2003, Anitmicrob
Agents Chemother, 47:413-415
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Response to Therapy Without
Complications of Co-Infection
Rapid resolution of
clinical signs
M t dogs
Most
d
hhave
significant
improvement in 24 to
48 hours
There are problems!
Are all these animals that are seropositive
infected  subclinical carriers of a zoonotic
disease
If animals can be sublclinically infected,
can we clear the organism with the current
therapy
Does Chronic Infection / Chronic
Disease Occur?
A. ovis can establish chronic infections
A. marginale causes productivity losses in
chronically infected cattle
Persistence despite antimicrobial therapy
Reduced weight gain due to chronic, subclinical A.
phagocytophilum infection in sheep
Anecdotal accounts of clinical disease associated
with A. phagocytophilum infection developing in
seropositive dogs after initiation of corticosteroid
therapy
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Human Anaplasmosis
Seroprevalence in endemic areas
14.9% of 475 permanent residents tested in Wisconsin
Appears to be a common subclinical or mild infection
* Bakken et al., Clin. Infect. Ds. 27:1491-1496, 1998
Outcome of treated cases
Survey: 85 previously treated cases (102 control)
Median interval from time of illness; 24 mo.
Patients had lower health status scores
Intermittent chills, fever, fatigue, sweats
Poorer health status relative to 1 year prior to infection
Antibody titers still elevated in one patient
Two had elevated AST
Post-infectious syndrome
Persistent infection
* Ramsey et al., Emer. Infect. Ds. 8:398-401, 2002
Three Inoculation Trials
Viable A. phagocytophilum organisms given
intravenously to dogs
Chronic persistent infections developed
Chronic,
Attempts to clear infection with
conventional antimicrobial therapy
Evidence of persistent Anaplasma
phagocytophilum infection in dogs
following doxycycline treatment9
Jeffrey R. Abbott*, Katherine Sayler**, Mellissa Clark* and A.
Rick Alleman**
*Department of Infectious Diseases and Pathology
**Department of Physiological Sciences
College of Veterinary Medicine
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Inoculations
Blood stabilate was used to inoculate one dog
(8H12)
Virulent field isolate (Baxter), MN
The remaining three dogs were infected with
stabilate from 8H12 once infection was
confirmed
Confirmation of infection
Serology
SNAP® 4Dx® Test (IDEXX Laboratories, Inc.)
All seroconverted between days 10–16 DPI
CBC
Neutropenia < 3000/µl (or decreasing counts)
As low as 920/µl
Blood and buffy-coat smears
Morulae in neutrophils
PCR (msp5)
Range from 3.7x103 to 1 x 105 copies per
5 µl of whole blood
Doxycycline treatment
Treatment: Began at 161 days PI
All dogs remained seropositive, but PCR-negative, during
treatment
Trial
T
i l dosage:
d
10 mg/kg
/k administrated
d i i t t d orally
ll
every 12 hours for 28 days
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Immunosuppression
2 weeks of rest to clear doxycycline
Prednisone:
2.2 mg/kg
Ad i i
Administrated
d orally
ll
Every 12 hours
14 days
PCR monitoring of blood
Recrudescence
PCR:
Positive values detected on days 5–6
postprednisone in 3 out of 4 animals
Remaining animal, on day 10 postprednisone
Verifying the viability of the
organisms
Three mixed-breed hounds were experimentally
inoculated.
Inoculum:
Postmortem tissues tested via PCR
Pancreas from dog 8H05 had highest numbers of bacteria
(3.3 x 104 /g tissue)
Postprednisone blood (4.3 x 103 /ml)
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Inoculation
Two dogs
Source: Blood
Route: IV
Volume: 2 ml
Bl d 5.0
Blood:
5 0 x 104 bacteria
b
i
One dog
Source: Pancreas extract
Route: IV
Volume: 2 ml
Pancreas extract: 3.3 x 103 bacteria
Bacteremia
Postinfection PCR analysis
Freckles(5M67) had neutropenia on day 11
(2,500/µl with 60 bands/µl; normal >3,000/µl)
Study Summaries
Persistent of infection for over 1 year
Seropositive for duration of trials
Sporadically PCR positive
Doxycycline therapy failed to clear organisms
This may not mimic natural infection especially in
treatment of acutely infected animals.
Value in rapid treatment of infected patients
Difficult to identify
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Amblyomma americanum
Eastern United States,
from central and eastern
Texas, north into
Missouri
Spreading east to the
coast
An aggressive northern
expansion of the tick is
occurring
Reports of LST in Maine
Activity of LST
Adult activity early as
February (warmer
climates)
Peak activity of adults in
spring and summer
May and June
Most common summer
tick in Florida
August begins larval
activity
September begins
nymph activity
Important Pathogens
Ehrlichia ewingii
Canine granulocytic ehrlichiosis (CGE)
Ehrlichia chaffeensis
Human monocytic ehrlichiosis (HME)
Ri k tt i rickettsii
Rickettsia
i k tt ii (RMSF)
Breitschwerdt et al. Emerg. Infect. Ds., vol. 17:2011,
Primary vector Dermacentor sp.
All zoonotic pathogens
Borrelia lonestari? – Southern Tick Associated
Rash Illness
Thus far only in humans
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Ehrlichia ewingii
Obligate, intracellular bacterium
Granulocytes (neutrophils of
mammalian host)
Causative agent of canine
granulocytic ehrlichiosis (CGE)
and human granulocytic
ehrlichiosis (HGE)
Infects dogs, people, goats and
deer (reservoir)
Prevalence of E. ewingii
Can be found anywhere in the geographic
boundaries of the LST
High seroprevalence in dogs in Missouri,
Texas, Arkansas and Tennessee
Over 30% of dogs seropositive in MO and TX
FL: 2.5% compared to E. canis 0.6% (N.C. FL)
Beall, Alleman, Breitschwerdt, Sayler et al. 2012. Parasites and Vectors, 5:29
Causes infection and disease in people
Prevalence data lacking
Clinical Signs with CGE
Nonspecific signs of illness (fever, lethargy,
anorexia)
Lameness associated with polyarthritis
Similar to Lyme and Anaplasmosis
Can cause acute disease and/or chronic,
persistent infections
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Serological Diagnosis of E. ewingii
Serological tests currently not
available (4Dx SNAP Negative)
4Dx Plus available soon, 2012
One Ehrlichia spp. spot
Positive control
Anaplasma
Ehrlichia
Lyme
E. canis, E. ewingii, E.
chaffeensis
Know which tick species!
BDT – E. canis
LST – E. ewingii and/or E.
chaffeensis (zoonotic infections)
Example: Prevalence in Arkansas
22 institutions and practices: seroprevalence of
Ehrlichia spp.in dogs in US
Beall, Alleman, Breitschwerdt et al, 2012 Parasites and Vectors, 5:29
44% dogs tested positive for Ehrlichia sp.
3.6% tested ppositive for E. canis
21.4% tested positive for E. chaffeensis
36.9% tested positive for E. ewingii
Does not add up to 44%?
17.9% were co-infected with two or more
Almost all co-infections were E. ewingii and E.
chaffeensis (L.S.T.)
E. chaffeensis
Intracellular agents that
reside in the monocytes
and lymphocytes of
infected hosts
Causes human monocytic
ehrlichiosis (HME)
Infection in dogs
presumably
indistinguishable from E.
canis
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Prevalence of E. chaffeensis
Can be found anywhere in the geographic
boundaries of the LST
High number or reported cases in humans in
Mi
Missouri,
i A
Arkansas
k
and
d Okl
Oklahoma
h
Spreading eastward and northerly
Infects people, dogs, primates (lemurs) and
several wildlife species including WTD and
coyotes
1990
Reported Cases 2007
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Clinical Signs of E. chaffeensis
Infection in Dogs
Waters muddy regarding
clinical infections in dogs
Suspected similar to E. canis
Multisystemic
y
disease
Experimental inoculation 
fever and thrombocytopenia
HME  flu-like symptoms
Can cause multisystemic disease
Neurological signs (meningitis)
Mortality (3% immunocompetent;
10% in immunocompromised)
Diagnostic Tests for E. chaffee
Serological assays
IFA for human infections
SNAP 3Dx or 4Dx cross-reactive with E.
canis
How many animals seropositive Positive control
f E.
for
E canis
i have
h
E chaffeensis?
E.
h ff
i ? Anaplasma
E. canis
Borrelia
N.C. FL: 2.1% vs. 0.6%;
NC: 5.7% E. chaffee vs. 0.7% E. canis
Beall et al, 2012 Parasites and Vectors, 5:29
PCR analysis for species identification
Unreliable in persistently infected carriers
(Seropositive and clinically normal)
Treatment E. ewingii and
E. chaffeensis
Doxycycline, 5-10
mg/kg BID for 28 days
No well established
protocol for dose or
length of therapy
Efficacious in treating
clinical disease
Are organisms cleared?
Anaplasma and Borrelia
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Combating tick-borne infections
Tick control is the one point where we all agree
Simultaneous exposure to multiple tick-borne
agents increases the likelihood of developing more
severe clinical disease
Ixodes – A. phagocytophilum, B. burgdorferi
Rhipicephalus – E. canis, A. platys, RMSF, Babesia
canis
Amblyomma – E. chaffeensis, E. ewingii, RMSF,
STARI, PME
Multiple arthropod vectors – Bartonella spp.
Thank You!
Dr. Tony Barbet
Dr. Jeff Abbott
Katherine Sayler
y
Dr. Tara Anderson
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