Emerging infectious diseases, particularly zoonotic diseases, have been the focus of scientific and public interest in recent years. Influenza A viruses (IAV), currently and historically have been zoonotic agents of great importance for both human and animal health. There is evidence of infection and exposure of numerous avian and mammalian species. Furthermore, studies have shown the potential of influenza viruses to cross species barriers, infecting many domestic and wild mammalian species. This thesis investigated exposure of multiple wild mammalian species to IAV to assess their potential role in the transmission and evolution of the viruses using serological methods. A number of factors were identified that promote influenza transmission and exposure. Contact between domestic and wildlife species, such as Asiatic wild asses with their sympatric relatives, was one factor. Furthermore, animals with both avian and mammalian influenza receptors in their respiratory tract, such as Equids, are more susceptible to influenza A virus infection, as we demonstrate in Chapter 3. The same effect is demonstrated in Chapter 2, where we showed that carnivores that consume birds had a higher diversity and greater exposure to AIV, while sociality and phylogenetic relationship does not seem to drive influenza exposure. If their susceptibility remains a dead-end infection, or are we facing a new endemic, and therefore potentially epidemic or pandemic infection, remains an open question. Serological surveys provide information about past infections, but molecular methods are needed in order to draw conclusions on the evolution and adaptation of the viruses in these potential new hosts. Integration of lo pathogenic IAV, LPAIV, in epidemiological studies, as well as IAV that are thought to no longer circulate, like H7N7 in equids, is of great importance. Wildlife may represent an unrecognized ecological niche for IAV. Additionally, constant and rapid change in the environment, such as climate change, agriculture practices, and habitat destruction, are influencing hosts, pathogens, and diseases and must be taken in account in wildlife disease surveillance studies. Integration and analysis of data from all these different sources, including animal and human data, will give us the tools to perform risk analysis, and apply possible control or prevention schemes.
