Important zoonotic diseases such as avian influenza, Lyme disease and Rift Valley Fever are also likely to spread due to global warming. Avian influenza viruses occur naturally in wild birds, though often with no dire consequences, however, a highly pathogenic strain of the disease-H5N1-is currently a major concern because it can affect humans. This is mainly because severe winter conditions and droughts, occasioned by climate change can disrupt the normal migration pathways of wild birds and thereby bring both wild and domestic bird populations into greater contact at remaining water sources.
The role of tick vectors in diseases like babesiosis in animals and Lyme disease in humans, and of mosquitoes in the transmission of viruses (Rift Valley Fever, Dengue fever, African horse sickness, Bluetongue) and parasites (Malaria) are all well known but the geographical distribution of these diseases is expanding as changes in climate continue. The dreadful impact of these diseases on health and the economy affects entire animal and human populations but the poorest communities are the most disadvantaged. The increased incidence in deadly infectious diseases in wildlife, livestock, and people may be one of the most important immediate consequences of global warming.