Surveillance and study of the epidemiology and evolution of these viruses are key areas for future research. The transmission of LPAIV from wild or domestic birds to swine has resulted in multiple lineages of influenza viruses that have become established in

swine populations, and are endemic in various regions of the world [7]. The diversity of swine influenza virus subtypes and lineages appears on the rise for the past decades, and is associated with high rates of reassortments in this species. It is possible that this is a novel phenomenon likewise in part due to the massive increase in swine production worldwide [31]. Occasionally, some strains of LPAIV have caused only one or few epidemics or have been isolated from pigs only sporadically, likely resulting from sporadic introductions from bird reservoirs without further establishment. CDK inhibitor Shared use of habitat or of drinking water with wild or domestic birds, consumption of carcasses or slaughter offal of these birds, or introduction by humans via contaminated utensils or vehicles are most likely the sources

of LPAIV infection in swine. GSKJ4 The transmission of LPAIV from birds to other mammals has resulted in the establishment of equine and canine influenza virus lineages in horse and dog populations, respectively; in occasional influenza epidemics in farmed American mink (Mustela vison) and harbour seals (Phoca vitulina); and in sporadic cases of infection in whales [7]. GBA3 Contacts with infected birds through shared use of habitats, shared feeding habits or consumption of infected birds likely Libraries favoured cross-species transmission of LPAIV in these species. Canine influenza viruses of the H3N8 subtype currently circulating

in dog populations are exceptions as they originated from an equine influenza virus, presumably after consumption of infected horse meat by racing greyhounds [32] and [33]. More recently, LPAIV H3N2 have been transmitted from birds to domestic dogs and may have established in this species in South-East Asia [34] and [35]. Among HPAIV, only HPAIV H5N1 have been transmitted from poultry to a wide range of wild and domestic birds and mammals [12]. Consumption of infected bird carcasses presumably resulted in the frequent transmission of these viruses to carnivores and predatory birds [7]. Animal bridge species infected with influenza viruses may become sources of infection for humans. The major sources of human infection with zoonotic influenza viruses are poultry and swine (Table 1). So far, no transmission of equine or canine influenza viruses to humans has been reported. However, transmission of avian and human influenza viruses to domestic dogs and cats are increasingly reported [34], [36], [37], [38], [39], [40] and [41].