Wildlife origin of emerging infections in animals and humans

Complex relationships between human and animal species have never ceased to evolve since the emergence of human and animal species. They have resulted in human-animal and animal-animal interfaces that have promoted... [ view full abstract ]

Complex relationships between human and animal species have never ceased to evolve since the emergence of human and animal species. They have resulted in human-animal and animal-animal interfaces that have promoted cross-species transmission, emergence and eventual evolution of a plethora of human and animal pathogens. Remarkably, most of the characteristics of these interfaces -as we know them today- have been established long before the end of our species pre-historical development, to be relentlessly shaped throughout the history of our own and animal species. More recently, changes affecting the modern human population worldwide as well as their dramatic impact on the global environment have taken domestication, agriculture, urbanization, industrialization, and colonization to unprecedented levels. This has created new global multi-faceted human-animal and animal-animal interfaces, associated with major epidemiological transitions, accompanied by an unexpected rise of emerging and re-emerging infectious diseases in humans, domestic and wild animals, that all have their origin in wildlife reservoirs. Until the beginning of the last century, infectious diseases were the major cause of mortality of humans and domestic animals. Around 1900 infectious diseases caused an estimated fifty percent of all human deaths in the western world. In the following decades, this percentage decreased to less than a few percent. This was largely due to the implementation of public health measures such as the installment of sewage and clean drinking water systems, but also to the development of vaccines and antimicrobials. Major successes in this regard were the eradication of smallpox and rinderpest through well-orchestrated vaccination campaigns in humans and cattle, respectively. Such successes prompted policymakers and scientists to predict that infectious diseases of humankind and of their domestic animals would eventually be brought under control in the industrialized world.