Lessons learned from the current
CEM-outbreak in South Africa
Schulman, ML1 and May, CE1,
1
Section of Reproduction, Faculty of Veterinary Science,
University of Pretoria
Background
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The first outbreak of contagious equine metritis
(CEM) due to the bacterium Taylorella equigenitalis
in South Africa was recognised in April 2011 and
reported to the OIE. As a consequence, South
Africa lost its CEM-free status. This outbreak report
was linked to the importation of the index case (a
Warmblood stallion) from Germany. An outbreak
was initially suspected following an unofficial test
breeding on the index property in Midrand (Gauteng
Province) of a Thoroughbred mare using semen
collected from the index stallion. Samples from
both index animals were confirmed positive for
T. equigenitalis after the State was notified and
submitted swabs for testing to a reference laboratory
in the UK. The index property was quarantined and
a traceback was instituted to identify and screen
all in-contact animals. This exercise was extended
country-wide as it became apparent that indirect
venereal transmission via movement of both carrier
stallions and chilled semen as well as horizontal
transmission via fomites was important in the
dispersal of T. equigenitalis from the index property.
The Department of Agriculture, Forestry and Fisheries
(DAFF) introduced a mandatory nationwide Stallion
Screening Programme in June 2011 to identify
carrier stallions which was central to assessing the
prevalence of T. equigenitalis and the extent of the
outbreak. Currently as of December 2013, a total
of 39 horses (36 stallions and 3 mares) have been
identified and after confirmation of their carrier
status were successfully treated under quarantine
conditions. All, with the exception of three horses
(North West = 2; Western Cape = 1) were identified
in Gauteng. Most positive animals have been linked
either directly or indirectly to the index premise.
The role of horizontal transmission via fomites (e.g.
personnel, housing, breeding equipment) has been
central and few animals appear to have been directly
infected by the venereal route. No evidence of classic
transmission at natural cover was recognised, and
the cases of venereal transmission were apparently
associated with AI using contaminated semen.
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2. Bacteriology and
pathogenesis
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CEM control was supported by the current
post-entry quarantine protocol
4. Diagnostic methods
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qPCR enabled accurate practical, highthroughput, rapid and economical
identification of T. equigenitalis
In-treatment qPCR improved therapeutic
protocols for T. equigenitalis elimination
Stallion screening was a practical and rapid
method to ascertain the prevalence of T.
equigenitalis
Repeat sampling increased the sensitivity
of T. equigenitalis detection
T. equigenitalis had the greatest
predilection for the urethral fossa and sinus
in stallions
5. Treatment and management
of carrier animals
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1. Epidemiology
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CEM transmission had a strong riskassociation with biosecurity
CEM was not exclusively a venereal disease
CEM was apparently readily contagious
CEM may have persisted for an undefined
interval outside the genital tract
environment
CEM was transmissible via AI using semen
diluted with antibiotic-containing extender
3. Disease prevention
Lessons learned:
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CEM transmission had a strong riskassociation with artificial breeding centres
CEM transmission and geographic dispersal
were facilitated by artificial breeding
CEM transmission was facilitated by
housing stallions in close proximity
CEM was absent in Thoroughbreds in SA
despite exclusive use of natural covering
CEM was absent in Arabian and American
Saddlehorses in SA
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The efficacy and duration of previouslyadvocated treatment protocols was
undefined
A treatment protocol to eliminate T.
equigenitalis was objectively evaluated
The treatment process may itself enhance
dispersal of T. equigenitalis
Topical treatment for T. equigenitalis
predisposed to genital colonisation by
• Volume 16 no 1 • March 2014 •
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