Transcript Horse infectious disease

Legislative background of horse
infectious disease surveillance
principles in EU with particular
reference to infectious metritis
Prof. Dr. Ivaylo Chenchev, PhD, DVSc
National Diagnostic and Research
Veterinary Medical Institute, Bulgaria
CONTAGIOUS EQUINE METRITIS
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Contagious equine metritis is an
inflammation of the endometrium of
mares
caused
by
Taylorella
equigenitalis, which usually results
in temporary infertility.
It is a nonsystemic infection, the
effects of which are restricted to the
reproductive tract of the mare.
CONTAGIOUS EQUINE METRITIS
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In general the clinical signs are a
slight to copious mucopurulent
vaginal discharge and a variable
cervicitis and vaginitis.
Recovery
is
uneventful,
but
prolonged asymptomatic carriage is
established in a proportion of
infected mares.
CONTAGIOUS EQUINE METRITIS
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Taylorella equigenitalis is most frequently
transmitted by sexual contact with carrier
stallions, which are always asymptomatic and in
which the principal sites of T. equigenitalis
colonisation are the urogenital membranes
(urethral fossa, urethral sinus, urethra and penile
sheath).
The sites of persistence of T. equigenitalis in the
mare are urogenital membranes, principally in the
clitoral sinuses and fossa and very infrequently in
the uterus.
Foals born of carrier mares may also become
carriers.
The organism can infect equid species other than
horses, e.g. donkeys.
CONTAGIOUS EQUINE METRITIS
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Contagious equine metritis was first
described in the United Kingdom in
1977, after which it was diagnosed in a
number of countries world-wide.
It first presented as disease outbreaks
characterised by a mucopurulent vaginal
discharge originating from inflammation
of the endometrium and cervix,
resulting in temporary infertility.
CONTAGIOUS EQUINE METRITIS
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Serum antibody persists for 3–7 weeks after
infection, but often it is not detectable for up to
15–21 days after recovery from acute infection in
the mares.
Most mares recover uneventfully, but some may
become carriers of T. equigenitalis for many
months.
Many primary cases of infection with T.
equigenitalis in the mare are subclinical, and a
frequent indicator of infection is a mare
returning in oestrus prematurely after being bred
to a putative carrier stallion.
CONTAGIOUS EQUINE METRITIS
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Carrier mares and stallions act as reservoirs of T.
equigenitalis, but stallions, because they mate
with numerous mares, play a much more
important role in transmission of the bacterium.
The urogenital membranes of stallions become
contaminated at coitus, leading to a carrier state
that may persist for many months or years.
Other sites of the horse’s body are not known to
harbour T. equigenitalis. Most carrier mares are
clitoral carriers of T. equigenitalis.
Taylorella equigenitalis can cause abortion in the
mare but this is a rare occurrence.
CONTAGIOUS EQUINE METRITIS
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Prior infection and vaccination are not fully
protective, and failure of antibody to persist has
meant that control of infection has relied entirely
on prevention of transmission through the
detection of T. equigenitalis on swabs of
urogenital membranes.
In spite of difficulties in culturing T.
equigenitalis, screening mares and stallions prior
to and while on the stud farm has successfully
eliminated the disease from thoroughbred horses
in countries using a voluntary code of practice.
Proposed minimum standards
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Housed in individual stalls
One empty stall between CEM
quarantine horses and other horses
– prevent direct contact
Groups of horses (Gypsies) can be
kept in same paddock together
(housed together before shipped)
Test mares separated after breeding
Helpful farm policies
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Individual water and feed buckets
cleaned daily
Isolation barn for sick horses
Monitor for feed intake and manure
Temperature daily
Concerns: EHV1, Strangles,
Influenza
Facilities should not harm horses
Mares and Stallions
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One person to hold mare
One person to hold tail
One person to handle stallion
One person to handle test mares
One person to assist breeding
Import mare procedures
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3 sets of clitoral sinus and fossa cultures
Interval – 3 days between cultures
Current regulations - 1, 4, and 7 days of a
7 day period
Complete cultures by 12 days after 1st
culture
How to get the swab from mare
Stallions – swab sample – urethral
sinus
Stallions – swab sample – urethral
sinus
Stallions – swab sample - Fossa
Stallions – swab sample - prepuce
Stallions – swab sample prepuce
Stallion – swab sample – terminal
urethral
Swab (Culture) sample handling
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Special media – Amies charcoal media
Refrigerate right away (4º C)
Needs to arrive to lab within 48 hours
Approved lab
Cultures read at 7 days after plating
Proposed clarification – read by hours 168 hrs vs 7 days
Test breeding of stallions
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After negative cultures – at least 7
days
Breed stallion to two qualified test
mares
Clean vulva and place tail bandage
on test mare
Tease stallion before breeding to see
if test mare is in heat
Test mare qualification
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3 negative sets of sinus and fossa
cultures with at least 3 days
between cultures
Negative CF test for CEM
Vaccinate test mares for EVA
Negative Coggins test (EIA)
Positive stallions
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Positive – Either initial culture, culture in
test mares or positive CF in test mares
Same procedures as described for
stallions after breeding
Treatment
Wait 21 days after last treatment
Repeat initial culture protocol and
procedures
Positive mares
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Positive culture or CF test in test mares
Same as previously described for import
mares after 3rd culture
Treatment
Wait at least 21 days
Repeat qualification protocols
Proposed – Identify and don’t use positive
test mares
Positive test mares - discharge
Example Treatment protocols – for
positive mares
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Sulfamethoxazole Trimethoprim (TMS) –
Systemic (30mg/kg PO) 5 days
1500 mg Gentamicin + 20 cc 8.4%
Sodium Bicarbonate + 25 cc saline – IU
for 3 days
Flush beans (Cerumene®) & sinuses (4%
Chlorhexidine) day 1
Scrub area for 2-5 days – 4%
Chlorhexidine
Pack area with 1% Silver Sulfadiazine 5
days
After Treatment protocols
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Wait 21 days
Repeat initial protocols – include
intra-uterine in one set of the 3
cultures
Test mares – negative CF
Example treatment protocol for
positive stallion
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TMS – 30mg/kg PO for 7 days
Scrub penis for 10 days with 4%
Chlorhexidine scrub
Pack penis for 10 days with 1% Silver
Sulfadiazine Cream
Wait 21 days before culturing
Culture at 21, 28 and 35 days after
treatment
Breed two test mares and follow
previously stated protocols – starting over
CONTAGIOUS EQUINE METRITIS
IDENTIFICATION OF THE AGENT
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Taylorella
equigenitalis
is a Gram-negative,
nonmotile, bacillus or cocco-bacillus that is often
pleomorphic (up to 6 μm long) and may exhibit
bipolar staining. It is catalase positive,
phosphatase positive, and strongly oxidase
positive.
If a slow-growing organism is isolated that fits
the description for cellular morphology and that
is strongly oxidase positive, it should be tested
for reactivity with T.-equigenitalis-specific
Agglutination method
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A
latex
agglutination
kit
is
available
commercially for the antigenic identification of T.
equigenitalis.
It is based on polyclonal antibodies.
This is widely used by routine testing
laboratories for the confirmation of the identity
of colonies growing on selective medium that
give a biochemical reaction consistent with T.
equigenitalis.
It should be emphasised that it will not
necessarily distinguish strains of T. equigenitalis
from T. asinigenitalis.
PCR method
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A PCR method has been used for detecting T.
equigenitalis and was compared with culture
methods.
It was highly specific and was able to detect very
small numbers of T. equigenitalis
PCR is more sensitive than culture for the
detection of T. equigenitalis from genital swabs
of horses in the field.
Real-time PCR is more useful and it uses directly
on genital swabs and compared with culture.
This PCR has advantage of speed of result and
also differents T. equigenitalis
from T.
asinigenitalis.