© ISTOCK.COM/ANYAIVANOVAThe disastrous and still ongoing Ebola epidemic in West Africa has highlighted the threat of newly emerged viral infections. As we observe the herculean attempts to contain the infection and the rush to test and approve underdeveloped drugs and vaccines, it is easy to overlook the true lesson to be learned from this situation—namely, how little we know about why and how certain viruses spill over from their natural hosts and how they interact with the human immune system.
Nearly 60 percent of all human pathogens are of zoonotic origin. This includes pathogens that have only very recently jumped to humans—such as Ebola, its emergence first reported several decades ago and again last year—as well as pathogens that have been with our species for hundreds or thousands of years. Smallpox, for example, most likely emerged in Central Africa as early as 2000 BC. Epidemiology tells us that the spread of a pathogen relies on perpetual contact with new groups of susceptible individuals. With the socioeconomic and environmental changes currently taking place, we are creating ideal conditions for the emergence and spread of zoonotic viruses. Moreover, the staggering increase in long-distance mobility (mainly via air travel) allows organisms—from people to pathogens—to jump around the world ...
