Ecology of avian influenza viruses in a changing world

Abstract

Influenza A virus infections result in ~500,000 human deaths per year and many more sub-lethal infections. Wild birds are recognized as the ancestral host of influenza A viruses, and avian viruses have contributed genetic material to most human viruses, including subtypes H5N1 and H1N1. Thus, influenza virus transmission in wild and domestic animals and humans is intimately connected. Here we review how anthropogenic change, including human population growth, land use, climate change, globalization of trade, agricultural intensification, and changes in vaccine technology may alter the evolution and transmission of influenza viruses. Evidence suggests that viral transmission in domestic poultry, spillover to other domestic animals, wild birds and humans, and the potential for subsequent pandemic spread, are all increasing. We highlight four areas in need of research: drivers of viral subtype dynamics; ecological and evolutionary determinants of transmissibility and virulence in birds and humans; the impact of changing land use and climate on hosts, viruses, and transmission; and the impact of influenza viruses on wild bird hosts, including their ability to migrate while shedding virus.

Epidemiological analysis of spatially misaligned data: a case of highly pathogenic avian influenza virus outbreak in Nigeria

“…Vandegrift et al also reviewed how anthropogenic change may alter the evolution and transmission of influenza viruses [33]. The initial outbreak of the disease in Nigeria was attributed to the movement of migratory birds [34]; this supports our findings of wind as a risk factor because the wind speed and direction may also affect the path of migratory birds thereby altering the spread of the virus.…”

The significance of naturally occurring neuraminidase quasispecies of H5N1 avian influenza virus on resistance to oseltamivir: a point of concern

“…Although person-to-person transmission of H5N1 avian influenza virus (AIV) appears to be very rare, its high fatality rate among those infected is a cause of great concern. Furthermore, the wide range of birds infected not only provided opportunity for efficient spread of the virus to new areas but also may have caused positive selection in newer host species (Vandegrift et al, 2010). Migratory birds, including storks, are widely blamed for the spreading of H5N1 viruses.…”

A social–ecological approach to landscape epidemiology: geographic variation and avian influenza

“…A confounding issue is that loss of wetland habitat may at least initially favour larger aggregations and overcrowding of waterfowl at remaining wintering, breeding and stopover sites. This in turn may lead to higher probabilities of contact between domestic and wild birds (Vandegrift et al 2010).…”

“…Most chickens and turkeys are produced from commercial parent breeds that are confined in houses of 15,000-70,000 birds (Leibler et al 2009). Although large commercial farms have good biosecurity and containment, the densities at which birds are housed facilitate rapid and efficient transmission of virulent AIVs (Vandegrift et al 2010).…”