UPDATE ON IRISH EQUINE INFLUENZA OUTBREAK

An increase in equine influenza was detected in Ireland towards the end of last year. BETWEEN THE END OF OCTOBER AND THE MIDDLE OF DECEMBER THE IRISH EQUINE CENTRE DIAGNOSED CASES OF INFLUENZA ON 15 PREMISES in counties Meath, Tipperary, Clare, Kildare, Dublin and Kilkenny. The initial outbreaks were in Non-Thoroughbred horses and ponies but in late November a Thoroughbred racehorse tested positive. In December equine influenza was confirmed in three racing yards and a stud farm.

Coughing and nasal discharge were the predominant clinical signs. Unvaccinated horses and young horses early in their vaccination career were worst affected. Older horses that had not received a booster during the previous six months were also vulnerable particularly on premises where recently introduced or unvaccinated young horses amplified the virus challenge. The Equine Centre used molecular techniques for rapid diagnosis and where equine influenza was confirmed offered assistance to the attending veterinary surgeons and their clients. By agreement with the owner affected premises were visited and samples collected from all horses. Repeat testing which was provided free of charge, allowed horse owners to monitor the status of their horses. This assisted in the day to day management of the horses, the shortening of recovery periods and the minimisation of virus spread. Informed control measures also benefited the wider horse industry as they reduce the risk to racing and other equestrian activities.

As an OIE (world Organisation for Animal Health) reference laboratory the Centre is actively engaged in equine influenza surveillance. This is essential for tracing the spread of viruses internationally and for the updating of vaccines. The virus identified during the 2014 outbreak is a Clade 2 virus of the Florida sub-lineage and the Centre will present this to the Expert Surveillance Panel of the OIE as further evidence that influenza vaccines need to be updated in a timely manner.

AT PRESENT ONLY ONE COMPANY (MERIAL) WITH VACCINES ON THE IRISH MARKET HAS UPDATED THEIR EQUINE INFLUENZA VACCINE WITH A CLADE 2 VIRUS. This updated Proteq-Flu vaccine which contains the Richmond 07 strain as a representative of Clade 2 viruses, became available in Ireland just before Christmas. Hopefully other vaccine manufacturers will soon follow Merial’s lead. Although the vaccines available in Ireland all provide protection they would be more efficacious if they contained virus strains that matched those in circulation in the field. As an OIE reference laboratory the Centre provides vaccine companies with recent virus strains free of charge for the purpose of updating their products.

VIROLOGICAL TESTING IS ONGOING ON SIX OF THE AFFECTED PREMISES BUT TO-DATE THIS YEAR, EQUINE INFLUENZA HAS NOT BEEN CONFIRMED ON ANY ADDITIONAL PREMISES. However those responsible for the management of horses should be vigilant as rapid diagnosis is the key to successful management of this disease.

DIAGNOSTIC TESTS FOR EQUINE INFLUENZA ARE PROVIDED FREE OF CHARGE BY THE IRISH EQUINE CENTRE. Free blood testing to determine if horses require booster vaccination is also provided and is strongly recommended for new arrivals irrespective of their documented vaccination history. In addition to these services a subvention is available towards the costs of sample collection by the veterinary surgeon on premises where equine influenza is confirmed. These activities are supported by the Department of Agriculture, Food and the Marine.