African Swine Fever - risk for humans (?)

• Tuberculosis probably jumped to humans when we began to domesticate goats and cattle 5000 years ago. 
• Measles appears to have evolved from canine distemper and/or the Rinderpest virus of cattle. 
• And Influenza, which is native to aquatic birds, became much more of a threat after humans domesticated ducks, geese, and chickens.

The last 30 years have seen a rise in emerging infectious diseases in humans and of these over 70% are zoonotic (2, 3). Zoonotic infections are not new. They have always featured among the wide range of human diseases and most, e.g. anthrax, tuberculosis, plague, yellow fever and influenza, have come from domestic animals, poultry and livestock. However, with changes in the environment, human behaviour and habitat, increasingly these infections are emerging from wildlife

4. Conclusions

Cross-species transmission of viruses from wild or domesticated animals is one of the main sources of emerging infectious agents in humans. Frequent outcomes of cross-species transmission are asymptomatic infection or dead-end events where the virus fails to establish in a new host species. However, rare but critical viral evolution in a new host can cause significant adaptations, leading to widespread outbreaks. From their natural reservoirs in wild waterfowl, IAVs have been transmitted to terrestrial birds and mammals, including humans (Figure 1). Viral adaptation in new hosts or genetic reassortment between human- and animal-origin IAVs in “mixing vessels” can lead to unpredictable changes, increasing zoonotic potential.

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If it were easy for nature to generate a successful pandemic virus, we'd be hip-deep in them all of the time. Luckily, most novel viruses are evolutionary failures, unable to compete against more `biologically fit' viruses. 

But it is a numbers game; the more diverse these viruses become - and the more hosts they inhabit - the better the chances are that a viable pandemic virus will emerge. 

That may not happen today, or even this year. But `viral chatter' (a term popularized by David Quammen) - referring to reports of novel flu spillovers into new species -  continues to grow at an unprecedented rate. 

Making it more a matter of when than if.