Epidemiological and virological investigations of equine influenza outbreaks in Ireland (2010–2012)
- 14 November 2013
- journal article
- Published by Wiley in Influenza and Other Respiratory Viruses
- Vol. 7 (s4), 61-72
- https://doi.org/10.1111/irv.12192
Abstract
Outbreaks of equine influenza (EI) in endemic populations cause disruption and economic loss. To identify (i) factors involved in the spread of EI (ii) virus strains responsible for outbreaks (iii) single radial haemolysis (SRH) antibody levels correlating with protection against current virus strains (iv) evidence of vaccination breakdown. RT-PCR, virus isolation and SRH were carried out on nasopharyngeal swabs and blood samples collected from horses, ponies and donkeys on affected premises. Data relating to 629 samples from 135 equidae were analysed. Outbreaks were sporadic, self limiting and associated with the movement of horses. Vaccination status and age influenced clinical signs of disease while housing and fomites contributed to virus spread. Subclinical infection as defined as a horse which tested positive by one or more of the following; RT-PCR, virus isolation and seroconversion in the absence of clinical signs, was identified in 9% of animals. Of the horses with up to date vaccination records 32% developed clinical signs. Vaccine breakdown occurred among horses vaccinated with all four commercially available vaccines. Analysis of HA1 sequence data generated for 26 viruses indicated that they all belonged to clade 2 of the Florida sublineage. Higher SRH antibody levels were required for both clinical and virological protection than reported in studies where vaccine strains were antigenically and genetically similar to those circulating in the field. The results of this study therefore support the OIE recommendations that vaccines be updated to include representatives of both clades of the Florida sublineage.Keywords
This publication has 40 references indexed in Scilit:
- Isolation and characterization of H3N8 equine influenza A virus associated with the 2011 epizootic in MongoliaInfluenza and Other Respiratory Viruses, 2013
- A comparison of antibody responses to commercial equine influenza vaccines following annual booster vaccination of National Hunt Horses – a randomised blind studyVaccine, 2011
- Genetic evolution of equine influenza viruses isolated in ChinaArchiv für die gesamte Virusforschung, 2010
- Equine influenza outbreak in India (2008–09): Virus isolation, sero-epidemiology and phylogenetic analysis of HA geneVeterinary Microbiology, 2009
- Clustal W and Clustal X version 2.0Bioinformatics, 2007
- Real-Time Reverse Transcription PCR for Detection and Quantitative Analysis of Equine Influenza VirusJournal of Clinical Microbiology, 2005
- Seroepidemiological and molecular evidence for the presence of two H3N8 equine influenza viruses in China in 1993-94Journal of General Virology, 1995
- Antigenicity and immunogenicity of equine influenza vaccines containing a Carbomer adjuvantEpidemiology and Infection, 1994
- The outbreak of equine influenza (H3N8) in the United Kingdom in 1989: diagnostic use of an antigen capture ELISAPublished by Wiley ,1993
- Are equine 1 influenza viruses still present in horses?Equine Veterinary Journal, 1993