AIDS, Avian flu, SARS, MERS, Ebola…what's next?

Complex relationships between the human and animal species have never ceased to evolve since the emergence of the human species and have resulted in a human-animal interface that has promoted the cross-species transmission, emergence and eventual evolution of a plethora of infectious pathogens. Remarkably, most of the characteristics of the human-animal interface -as we know it today- have been established long before the end of our species pre-historical development took place, to be relentlessly shaped throughout the history of our 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 a unique global multi-faceted human-animal interface, associated with a major epidemiological transition that is accompanied by an unexpected rise of new and emerging infectious diseases. Until the beginning of the last century, infectious diseases were the major cause of mortality of humankind. Around 1900 infectious diseases caused an estimated fifty percent of all deaths in the western world. In the following decades, this percentage decreased to 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 antimicrobial compounds. A major success in this regard was the eradication of smallpox through a worldwide vaccination campaign orchestrated by the World Health Organization (WHO). Stimulated by these successes certain policymakers and scientists predicted that all infectious diseases of humankind would be brought under control. Paradoxically the following decades confronted the world with an everincreasing number of emerging or re-emerging infectious diseases, some causing true pandemics. Striking examples were the emergence of AIDS, Avian flu, SARS, MERS, and Ebola. Viruses spilling over from animal reservoirs caused these disease outbreaks. A complex mix of predisposing factors in our globalizing world, linked to major changes in our social environment, technology and global ecology ,collectively created opportunities for viruses to infect new hosts. Subsequent adaptation to the newly invaded species then paved the way for an unprecedented spread with dramatic consequences for public health, animal health, animal welfare, food supply, economies, and biodiversity. Importantly, these developments are largely paralleled by medical, technological, and scientific progress, continuously spurred by our never-ending combat against pathogens. Investment in a better understanding of the human-animal interface will therefore offer humankind a future head start in the never-ending battle against infectious diseases. Recent events like the emergence in humans of avian influenza, MERS and Ebola**, have highlight the urgent need for this investment.