Detection of clade 2 equine influenza virus in an adult horse recently imported to the USA

Abstract

Summary A 4‐year‐old Warmblood mare presented to the William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California at Davis with bilateral mucoid nasal discharge and pyrexia. The mare had recently been imported from Germany, arriving at a quarantine holding facility 72 h prior to presentation. Based on clinical presentation and culture results of tracheal fluid, the mare was diagnosed with bacterial bronchopneumonia secondary to equine influenza. The equine influenza virus (EIV) identified in the imported mare displayed 99.1% nucleotide homology of the HA1 gene to the prototype Florida sublineage clade 2 isolate A/equine/Richmond/1/2007 (H3N8). This case illustrates the risk of introducing a clade 2 EIV in North America.

Pyrosequencing as a fast and reliable tool to determine clade affiliation for equine Influenza A virus

“…The EIV Florida sublineage prototypes A/equine/Ohio/1/2003 and A/equine/Richmond/1/2007 were accurately classified as clade 1 and clade 2, respectively, based on the appropriate nucleotides at each of the 2 SNPs of the HA1 gene. 13 Genetic characterization of the EIV identified in the imported mare displayed 99.1% nucleotide homology of the HA1 gene to the prototype Florida sublineage clade 2 isolate A/equine/Richmond/1/2007. 13 Similar to the mare previously reported in the literature, the 3 clade 2 EIV strains originated from adult horses with a recent import history from European countries, where both clade 1 and clade 2 EIVs are endemic.…”

Outbreak of equine influenza in Croatia in 2015 and post outbreak epidemiological situation

“…2), confirming the international movement of sub-clinically infected animals as the most likely source of EI infection in the Croatian outbreak. Due to the significant increase in the sport and leisure horse population during the last two decades in Croatia, both national and international movement may be considered important risk factors for EI spread and introduction of new viral strains, as has been seen in other countries (PUSTERLA et al, 2014;BACK et al, 2016).…”

Equine influenza and air transport

“…Over 75,000 horses were affected prior to the eradication of the virus at an estimated cost of approximately one billion Australian dollars. Like the incident described by Pusterla et al (2014), these incursions into South Africa, Japan and Australia were due to the importation of infected vaccinated horses. Vaccines may provide clinical protection but frequently fail to prevent virus shedding.…”

“…In this issue of Equine Veterinary Education, Pusterla et al (2014) report the detection of a clade 2 equine influenza virus (EIV) in a 4-year-old vaccinated mare recently imported from Germany to the USA. Clade 2 viruses predominate in Europe and have caused major outbreaks of influenza in Asia (reviewed by Cullinane and Newton 2013).…”

“…The World Organisation for Animal Health (OIE), Terrestrial Animal Health Code recommends that horses are vaccinated against equine influenza between 21 and 90 days before shipment either with a primary course or a booster but there is currently an absence of international standardisation amongst importing countries. The mare discussed by Pusterla et al (2014) had not been vaccinated for over a year and the United States Department of Agriculture's Protocol for the Importation of Equines makes no reference to vaccination against equine influenza. The mare had exhibited signs of respiratory disease while in a quarantine holding facility in the USA.…”