Epidemiology and reproductive outcomes of EHV-1 abortion epizootics in unvaccinated Thoroughbred mares in South Africa.
Abstract: Equine herpesvirus 1 (EHV-1) is one of the most common causes of infectious abortion in mares. Analysing the demography of outbreaks and detailing subsequent reproductive performance of affected mares will assist in the management of future (threatened) epizootics. Objective: To examine the epidemiology and reproductive outcomes of 2 EHV-1 abortion epizootics with very different patterns of morbidity. Methods: Epidemiological and reproductive data were analysed retrospectively following abortion epizootics associated with EHV-1, but initiated via different routes, among unvaccinated mares on 2 Thoroughbred farms in South Africa. Methods: Aborting mares were assigned to either the EHV-1 abortion cohort via positive immunostaining (Farms 1 and 2) or quantitative PCR (Farm 2) on tissue samples, or to the non-EHV abortion cohort. Results: During their respective epizootics, EHV-1 abortions affected 9/30 (30.0%) and 18/316 (5.7%) of the pregnant mares on Farms 1 and 2, respectively; there were also 25 (7.9%) non-EHV abortions on Farm 2. Epizootic differences included: durations (Farm 1 = 135 days; Farm 2 = 34 days), intervals between first and subsequent abortions (Farm 1 = 39 days; Farm 2 = 2 days) and intervals to confirmation of EHV-1 (Farm 1 = 40 days; Farm 2 = 2 days). The median (range) age of EHV-1 abortion mares (8.0; 5-18 years) in both epizootics was similar but significantly younger (P = 0.004) than the 25 non-EHV-1 abortion mares (11.0; 4-24 years) on Farm 2. Gestation stage (median; range) of EHV-1 (291.5; 277-313) and non-EHV-1 (211.9; 61-339 days) abortions were significantly different (P = 0.001). The post abortion complications and subsequent reproductive outcomes had no significant association with EHV-1 abortion. Conclusions: The marked difference in morbidity between the 2 epizootics may be associated with routes of introduction or intervention strategy dictated by availability of molecular diagnostic techniques. Unexpectedly, EHV-1 was not more commonly associated with post abortion complications.
© 2014 EVJ Ltd.
Publication Date: 2014-05-09 PubMed ID: 24617603DOI: 10.1111/evj.12264Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This research article investigates the epidemiology and after-effects of Equine herpesvirus 1 (EHV-1) abortion in unvaccinated Thoroughbred mares in South Africa. The study reveals notable differences in the extent of infection and associated factors in two separate outbreaks, however, post-abortion complications were not found to have a significant association with EHV-1.
Research Objective and Methodology
- This research aimed to understand the epidemiology and reproductive results of two EHV-1 abortion epidemics in South African Thoroughbred farms. Understanding the characteristics of these outbreaks and the subsequent breeding performance of the affected mares would aid in managing potential future outbreaks.
- The data for the research was gathered retrospectively after the abortion outbreaks associated with EHV-1. The outbreaks were started by different routes among unvaccinated mares on two separate Thoroughbred farms.
- Mares suffering abortions were assigned to the EHV-1 abortion cohort or the non-EHV abortion cohort. The classification was done based on positive immunostaining or quantitative PCR on tissue samples.
Key Findings
- EHV-1 affected 30% (9 out of 30) and 5.7% (18 out of 316) of the pregnant mares on the two different farms, respectively.
- There were significant variations between the two epidemics, including the duration of the outbreak and intervals between first and subsequent abortions.
- The median age of EHV-1 abortion mares (8 years, ranging from 5 to 18 years) in both the outbreaks was similar but significantly younger than those subject to non-EHV-1 abortions (median 11 years, ranging from 4 to 24 years).
- In terms of the gestation stage at which abortions were noted; EHV-1 abortions and non-EHV-1 abortions each happened at significantly different time frames.
- There were no significant associations found between post-abortion complications and subsequent reproductive outcomes with the EHV-1 associated abortion.
Conclusions
- The substantial difference in the degree of infection between the two outbreaks could be associated with different routes of the disease’s introduction or due to varying intervention strategies.
- Interestingly, EHV-1 was not found to be associated more frequently with post-abortion complications, contradicting some expectations.
Cite This Article
APA
Schulman ML, Becker A, van der Merwe BD, Guthrie AJ, Stout TA.
(2014).
Epidemiology and reproductive outcomes of EHV-1 abortion epizootics in unvaccinated Thoroughbred mares in South Africa.
Equine Vet J, 47(2), 155-159.
https://doi.org/10.1111/evj.12264 Publication
Researcher Affiliations
- Section of Reproduction, Faculty of Veterinary Science, University of Pretoria, South Africa.
MeSH Terms
- Abortion, Veterinary / epidemiology
- Abortion, Veterinary / prevention & control
- Abortion, Veterinary / virology
- Animals
- Case-Control Studies
- Disease Outbreaks / veterinary
- Female
- Herpesviridae Infections / prevention & control
- Herpesviridae Infections / veterinary
- Herpesviridae Infections / virology
- Herpesvirus 1, Equid
- Horse Diseases / epidemiology
- Horse Diseases / prevention & control
- Horse Diseases / virology
- Horses
- Pregnancy
- Pregnancy Complications, Infectious / veterinary
- Pregnancy Complications, Infectious / virology
- South Africa / epidemiology
- Viral Vaccines / administration & dosage
- Viral Vaccines / immunology
Citations
This article has been cited 2 times.- Stasiak K, Dunowska M, Rola J. Outbreak of equid herpesvirus 1 abortions at the Arabian stud in Poland.. BMC Vet Res 2020 Oct 6;16(1):374.
- Bryant NA, Wilkie GS, Russell CA, Compston L, Grafham D, Clissold L, McLay K, Medcalf L, Newton R, Davison AJ, Elton DM. Genetic diversity of equine herpesvirus 1 isolated from neurological, abortigenic and respiratory disease outbreaks.. Transbound Emerg Dis 2018 Jun;65(3):817-832.
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