Humans and livestock interact closely, especially in many pastoralist communities where people live together with their livestock, and in urban agriculture, where the sheer lack of space forces the livestock closer upon the... [ view full abstract ]
Humans and livestock interact closely, especially in many pastoralist communities where people live together with their livestock, and in urban agriculture, where the sheer lack of space forces the livestock closer upon the humans. Thus, human and their livestock comes to share the same environment, the same living spaces, and to a large extent, also the same pathogens. Globally, infections, including parasitic diseases, contributes more than 20% of the global burden of disease, but there are large differences, and in Africa the contribution is more than 70%. The reasons behind disease emergence can be diverse, with demographic, land use and climate changes interacting. Climate-sensitive diseases, such as the vector-borne and water-borne, are expected to be affected by changes in climate, precipitation and temperature, but climate change may also affect land use, urbanization and interaction between livestock, wildlife and humans indirectly. Urbanization brings humans and animals closer, with increased transmission between them as a consequence, and globalization and animal movements cause both vectors and pathogens to spread. The role of wildlife is often not fully understood. Increased biodiversity have sometimes been claimed to have a dilution effect on diseases, including vector-borne diseases, but this is not true for all ecosystems and diseases, since it depends on the host specificity of the pathogens. In addition peri-domestic wildlife, such as rats, bats and scavengers may bring pathogens closer to humans. Many vector-borne diseases have a complex epidemiology, dependent on the vector dynamics, which is dependent on environment and climate, and the ecology of the reservoir hosts, which can be both domestic and wild. In the case of Rift Valley fever (RVF), it is believed that wildlife may play an important role in maintaining the virus during inter-epidemic periods, but this has still not been established. In order to predict future emergence of RVF, it is important to understand how changes in land use, biodiversity and climate will influence the epidemiology, and this is the basis of our project in the Tana River delta that studies the impact of increased irrigation and reduced wildlife on RVF seroprevalence.
