This dissertation describes the epidemiological investigation and management of the first
outbreak of Contagious Equine Metritis (CEM) reported in South Africa. In addition, the
subsequent implementation of a nationwide quantitative polymerase chain reaction (qPCR)-
based stallion screening programme and traceback of exposed animals to define the spread of
CEM in South Africa is described.
The first South African outbreak of CEM caused by the bacterium, Taylorella equigenitalis
was reported on the 9th May 2011 to the World Health Organisation for Animal Health (OIE).
The outbreak was recognized subsequent to the importation of a young Warmblood stallion
from Germany. The outbreak initially appeared confined to a single index property (focus
property), an equine breeding facility in Midrand, Gauteng, South Africa with a single
confirmed case of transmission involving the index stallion and a Thoroughbred mare.
The initial response was rapidly instituted following the suspicion of T. equigenitalis on the
index property. This included an inspection of the index property and its records. A riskclassification
of in-contact animals allocated them to “high,” “moderate” or “low”-risk
categories. The classification was dependent on the temporal relationship of their presence on
the index property relative to the period of residence of the index cases. After T. equigenitalis
infection was confirmed from both index cases, the breeding facility was placed under state–
administered quarantine and all exposed mares and the index cases were transferred to a
quarantine facility. The animals were re-tested by genital swabbing for bacterial culture
following a standard protocol according to internationally-accepted practice (OIE Terrestrial
Manual on Contagious Equine Metritis). Additional duplicate swabs were obtained for real
time qPCR. None of the mares were shown to be positive on either bacterial culture or qPCR.
All animals were however treated according to an accepted protocol for T. equigenitalis
infection (Luddy and Kutzler, 2010, UK Horseracing Betting Levy Board (HBLB) Code of
Practice, 2011).
All stallions that had been present on the index property and undergone semen collection on
the same day as the index stallion were classified as “moderate risk” and were similarlytested. This identified two additional T. equigenitalis-positive stallions, which were
confirmed on bacterial culture (World Organization for Health (OIE) Manual of Diagnostic
Tests and Vaccines for Terrestrial Animals (Chapter 2.5.1, Contagious Equine Metritis
version adopted 20/10/2011) and which were subsequently quarantined and successfully
treated.
Following recognition of this outbreak, the Department of Agriculture, Forestry and Fisheries
(DAFF) in consultation with the Equine Research Centre (ERC) of the Faculty of Veterinary
Science at the University of Pretoria promulgated a nationwide qPCR-based screening
programme that aimed to establish the prevalence and distribution of T. equigenitalis in South
Africa. This required certification of all South African stallions used for breeding either by
natural cover or assisted reproductive techniques. The compliance for certification was based
on submission of two sets of genital swabs that both tested negative for T. equigenitalis on
qPCR-testing. The process was coordinated by a web-based platform
(http://wto the prescribed World Organisation for Health (OIE) method (Terrestrial Manual on
Contagious Equine Metritis). All stallions apart from one could be linked to the index
property.
As of 31st October 2013, two additional T. equigenitalis-positive females have been
identified, following a traceback of all identified potentially-exposed mares and their
offspring that was instituted in September 2012. An “exposed mare” was defined as a mare
that had been bred, either by natural breeding or assisted breeding techniques to the index
stallion or any other T. equigenitalis-positive stallion. These mares were distributed across
five provinces of South Africa at the time the traceback was initiated.
During the nationwide traceback, a subpopulation focus was identified when 24 of the 33
resident stallions at the South African Lipizzaner Centre, Midrand, Gauteng tested positive
for T. equigenitalis. Six of these stallions had visited the index property for semen collection
over the course of several years prior to the arrival of the index stallion. This suggested the
possible albeit undetected presence of T. equigenitalis on these premises prior to the arrival
of the first reported index case. We strongly suspected that there may have been undetected
CEM incursions into South Africa in the past. The index case in this outbreak may either
have introduced a new infection or was infected by a pre-existing source of infection
subsequent to his arrival. It is hoped that future strain-typing of the isolates from the positive
cases identified during this intervention will further clarify this scenario.
The use of qPCR-based screening proved to be a highly specific and sensitive method for
detecting T. equigenitalis and helped to define the distribution and prevalence of T.
equigenitalis in breeding stallions and exposed mares in South Africa. In addition, this
method had significant practical advantages with respect to the associated costs, turn-around
times and in-the-field application when compared with bacterial culture. The institution of a
web-based platform from which the national screening programme was launched and coordinated
proved to be indispensable in managing stakeholder access and information
availability.
To date, 31st October 2013, a total of 39 horses (36 males and 3 females) have been identified
as T. equigenitalis-positive and have all subsequently been successfully treated.
© Universityww.cemsa.co.za)
As of 31st October 2013, an additional 33 carrier stallions have been identified by this
screening programme. Of these stallions, 23 have been confirmed on bacteriology according to the prescribed World Organisation for Health (OIE) method (Terrestrial Manual on
Contagious Equine Metritis). All stallions apart from one could be linked to the index
property.
As of 31st October 2013, two additional T. equigenitalis-positive females have been
identified, following a traceback of all identified potentially-exposed mares and their
offspring that was instituted in September 2012. An “exposed mare” was defined as a mare
that had been bred, either by natural breeding or assisted breeding techniques to the index
stallion or any other T. equigenitalis-positive stallion. These mares were distributed across
five provinces of South Africa at the time the traceback was initiated.
During the nationwide traceback, a subpopulation focus was identified when 24 of the 33
resident stallions at the South African Lipizzaner Centre, Midrand, Gauteng tested positive
for T. equigenitalis. Six of these stallions had visited the index property for semen collection
over the course of several years prior to the arrival of the index stallion. This suggested the
possible albeit undetected presence of T. equigenitalis on these premises prior to the arrival
of the first reported index case. We strongly suspected that there may have been undetected
CEM incursions into South Africa in the past. The index case in this outbreak may either
have introduced a new infection or was infected by a pre-existing source of infection
subsequent to his arrival. It is hoped that future strain-typing of the isolates from the positive
cases identified during this intervention will further clarify this scenario.
The use of qPCR-based screening proved to be a highly specific and sensitive method for
detecting T. equigenitalis and helped to define the distribution and prevalence of T.
equigenitalis in breeding stallions and exposed mares in South Africa. In addition, this
method had significant practical advantages with respect to the associated costs, turn-around
times and in-the-field application when compared with bacterial culture. The institution of a
web-based platform from which the national screening programme was launched and coordinated
proved to be indispensable in managing stakeholder access and information
availability.
To date, 31st October 2013, a total of 39 horses (36 males and 3 females) have been identified
as T. equigenitalis-positive and have all subsequently been successfully treated. / Dissertation (MMedVet)--University of Pretoria, 2013. / gm2014 / Production Animal Studies / unrestricted
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:up/oai:repository.up.ac.za:2263/40706 |
| Date | January 2013 |
| Creators | May, Catherine Edith |
| Contributors | Schulman, Martin L., kate.may@up.ac.za, Guthrie, Alan John |
| Publisher | University of Pretoria |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Dissertation |
| Rights | © 2013 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. |
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