Transmission of Equine Influenza Virus to Dogs

Abstract

Molecular and antigenic analyses of three influenza viruses isolated from outbreaks of severe respiratory disease in racing greyhounds revealed that they are closely related to H3N8 equine influenza virus. Phylogenetic analysis indicated that the canine influenza virus genomes form a monophyletic group, consistent with a single interspecies virus transfer. Molecular changes in the hemagglutinin suggested adaptive evolution in the new host. The etiologic role of this virus in respiratory disease was supported by the temporal association of rising antibody titers with disease and by experimental inoculation studies. The geographic expansion of the infection and its persistence for several years indicate efficient transmission of canine influenza virus among greyhounds. Evidence of infection in pet dogs suggests that this infection may also become enzootic in this population.

Epidemiology and Ecology of H3N8 Canine Influenza Viruses in US Shelter Dogs

“…In the case of CO, there was no more detectable CIV after March 2011, when the virus appears to have disappeared. In contrast, the FL humane shelter had much lower than expected CIV nasal shedding, given the fact that CIV first emerged in the state and previous FL shelter studies showed relatively higher prevalence 1. On the other hand, the humane shelter in SC had more than expected CIV nasal shedding, which can be attributed to a CIV outbreak during the first months of sample collection (Fig 1).…”

“…Canine influenza virus (CIV) (H3N8) was first detected in Florida (FL) racing greyhounds in 2004 and quickly spread into New York (NY) and FL shelter dog populations 1. The transmission of influenza A viruses is thought to be by direct contact, deposition of infectious droplets (≥5 μm) on nasal or oral mucosa, or inhalation of infectious particles (<5 μm) 2.…”

“…Indeed, humane shelters have consistently reported high rates of CIV in dogs exhibiting signs of canine infectious respiratory disease (CIRD). In a NY and FL humane shelter study conducted shortly after CIV emergence, up to 97% of dogs were seropositive for CIV 1. Similarly, dogs from humane shelters in Colorado (CO) were infected with CIV in 5 of 5 humane shelters reporting CIRD outbreaks in 2006 and 2007 5.…”

Influenza A virus infection of healthy piglets in an abattoir in Brazil: animal-human interface and risk for interspecies transmission

“…Transmission and subclinical infection of human and avian H3N2 (Houser & Heuschele 1980, Song et al 2008), equine H3N8 (Crawford et al 2005), avian H5N1 (Songserm et al 2006b) and the pandemic 2009 H1N1 (Damiani et al 2012) influenza virus strains to dogs have been documented. Serological evidence of naturally acquired infections caused by seasonal human H1N1 and H3N2 (Ali et al 2011), the pandemic 2009 H1N1 (Sponseller et al 2010, Ali et al 2011), and the avian H5N1 (Songserm et al 2006a) influenza virus strains in cats have also been reported.…”

The avian‐origin H3N2 canine influenza virus that recently emerged in the United States has limited replication in swine

“…Two established lineages of H3 canine influenza virus (CIV) have been described, of equine‐origin and avian‐origin 1. An H3N8 equine influenza virus (EIV) initially caused outbreaks in racing greyhounds in the United States in 20042, 3; however, epidemiological and serological evidence indicated that an H3N8 equine virus introduction around 1999 was likely the ancestral strain of the H3N8 CIV in the United States 4, 5. While there was evidence of additional EIV transmission events into dogs in the United States,6 there was no evidence of sustained transmission of these other events, nor were there reports of CIV transfer back to horses or to humans 7.…”