Topical issues in equine infectious disease Dr Richard Newton FRCVS Animal Health Trust
Overview • Finding information on equine infectious disease occurrence – Domestic UK – International • Some events of note in 2017 – CEM unexpectedly found in France – Break in supply of EVA vaccine – EIA re-emerges in Europe – Neurological EHV-1 affecting TBs –
Overview • Finding information on equine infectious disease occurrence – Domestic UK – International • Some events of note in 2017 – CEM unexpectedly found in France – Break in supply of EVA vaccine – EIA re-emerges in Europe – Neurological EHV-1 affecting TBs –
Unexpected CEM in France Contagious Equine Metritis (CEM) • Bacterial cause of infertility in mares • Natural & artificial venereal transmission • T. equigenitalis carried subclinically by mares, stallions & teasers • HBLB Code of Practice cornerstone of control – Annual pre-breeding screening; approved labs • CEM notifiable under ‘IDHO 1987’ – Facilitates international trade in bloodstock
Unexpected CEM in France • Reported by RESPE on 20 November 2017 • Confirmed by reference lab on 27 October 2017 • Subclinical infection of undetermined origin in yearling TB filly on routine pre-export testing • Second sample negative, treatment completed
Unexpected CEM in France • Further information provided by RESPE: • Small mixed breed premises – 4 Thoroughbred mares & offspring (incl. case) – 1 Paint Horse broodmare – 3 French Saddlebred broodmares – 3 geldings • Dam of case (based in UK) has tested CEMO negative
Overview • Finding information on equine infectious disease occurrence – Domestic UK – International • Some events of note in 2017 – CEM unexpectedly found in France – Break in supply of EVA vaccine – EIA re-emerges in Europe – Neurological EHV-1 affecting TBs –
Break in supply of Artervac Equine Viral Arteritis (EVA) • Acute viral disease of horses, incl. abortion • Transmitted by respiratory & venereal routes • Virus (EAV) shed long-term in semen in some recovered ‘carrier’ stallions • First recorded outbreak in UK in 1993 in imported non- Thoroughbred ‘carrier’ stallion • EVA in stallions notifiable in ‘EVA Order 1995’ • Artervac EVA vaccine used to protect stallions
Break in supply of Artervac Equip Artervac EVA vaccine (Zoetis) • Requires booster doses every 6 months • No new supply after batch expired 26 Nov 17 – Date of resumption of supply not yet known • Stallions will lapse in EVA vaccination in 2018! – Seropositive stallions w. lapsed vaccination Hx may require semen testing under EVA Order 1995
Break in supply of Artervac Protocol agreed to avoid semen testing • Blood testing to confirm no significant rise in antibody to EAV => no infection!
Break in supply of Artervac Protocol agreed to avoid semen testing • Collect blood samples in January & July each year until Artervac available again
Break in supply of Artervac • Vets submit blood samples to AHT on special submission form • AHT registers samples and store them frozen for later testing • All samples from same animal tested together on same test http://www.aht.org.uk/skins/Default/pdfs/Artervac_Form_v2.pdf
Break in supply of Artervac • Covered in 2018 EVA Code of Practice – Page 21
Overview • Finding information on equine infectious disease occurrence – Domestic UK – International • Some events of note in 2017 – CEM unexpectedly found in France – Break in supply of EVA vaccine – EIA re-emerges in Europe – Neurological EHV-1 affecting TBs –
EIA re-emerges in Europe Equine Infectious Anaemia (EIA) • Retroviral disease of horses; cf human HIV • Transmitted by blood transfer; including biting insects & contaminated needles & products • Recovered horses can act as sources of infection; no treatment or vaccination – Notifiable disease requiring mandatory slaughter • Outbreaks in Ireland in 2006, UK in 2010 & 2012 & elsewhere in Europe in summer 2017
EIA re-emerges in Europe • Italy & Romania considered endemic for EIA • Isolated cases in Europe in last 5 years in Belgium, Bulgaria, Croatia, France, Germany, Greece, Hungary, Slovakia & Slovenia
EIA re-emerges in Europe
EIA re-emerges in Europe
Overview • Finding information on equine infectious disease occurrence – Domestic UK – International • Some events of note in 2017 – CEM unexpectedly found in France – Break in supply of EVA vaccine – EIA re-emerges in Europe – Neurological EHV-1 affecting TBs –
Neurological EHV-1 in TBs Equine Herpes Virus-1 (EHV-1) • Acute & latent viral infections of horses – Latency makes EHV-1 impossible to eradicate • Respiratory, abortion & neurological signs • Need to manage outbreaks when they occur – Use of clinical & laboratory monitoring to establish extent of infection & confirm when cleared
Neurological EHV-1 outbreaks • Occasionally in horses in training & on studs • Occasionally multiple outbreaks simultaneously – November 2012 through to April 2013 • After a quiet 2014 & 2015, increased EHV-1 activity seen in TBs in 2016 and 2017
Neurological EHV-1 in TBs • Neurological EHV-1 in TBs since 2016 – Confirmed at National Stud in late Jan 2016 – Suspected cases investigated linked to TB yards in Newmarket & Epsom in 2016 & Devon in 2017 – Confirmed in N. Yorks training yard in 2017
National Stud • Ataxia in recently imported 4yo mare – Seroconversion to EHV-1/-4 in 6 days – But 4 NP swabs negative by qPCR • Whole stud closed immediately & issued press release • Biosecurity measures as per CoP • All 24 mares in the isolation unit were screened clear – No clinical disease, no seroconversions – Post-foaling placentae PCR negative • Main stud re-opened on 15/2/16 & isolation yard re-opened on 23/2/16
N. Yorkshire training yard • Single fatal case confirmed 31 st May 2017 – Positive EHV-1 qPCR on pre-mortem swab & post- mortem tissues • BHA informed & yard voluntarily closed • Clinical & laboratory monitoring of 121 horses – Infection risk categorisation adopted for clearance – Racing from cleared barns allowed after 18 th June with negative NP swabs by qPCR within 48 hrs • Yard declared clear by end of June 2017
N. Yorkshire training yard
Concluding remarks • Recent issues in Europe with CEM & EIA • Recent issues in UK with EVA vaccine availability & neurological EHV-1 • All 4 diseases are covered by the HBLB Codes of Practice – Still relevant as industry standard for infectious disease prevention & control after 40 years – Some parts are still supported by UK legislation • Use resources to monitor equine diseases – Defra & International Collating Centre reports
Acknowledgements
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