[dllthomas]

Ah, yeah, that is a bit of a different angle on it. Truth be told, I'm not sure whether or not we're underrating the risk. On the one hand, increased travel and population density should see faster spread.

On the other hand we have a lot of changes in our favor: understanding how diseases are spread (starting with germ theory, all the way up through population models), understanding how many more diseases are treated, an astoundingly better ability to communicate, probably a better ability to coordinate...

I don't know how it nets out. The streak we've had should be taken as some evidence that it breaks in our favor. Certainly we should not succumb to the gambler's fallacy, there. However, I think we're well served to keep an eye on things.

[danieltillett]

Yes it is really difficult to know how the two major forces are tipping the likelihood. We have a better understanding of how contagious disease is spread and on average much better immune systems because of better diets (the average person was starving when most plagues struck in the past). Balancing this is as you mention increased travel and much high population densities. You just have to see the spread of a contagious disease through a modern animal feedlot to know what this does. All of this makes it really hard to know which way the risk has changed.

My biggest fear is a pandemic Rhadinovirus since it is airborne, has a long incubation phase and leukaemia is the outcome [1]. Something like a human pathogenic Ateline or Saimiriine herpesvirus could spread through the human population without us knowing until it is too late.

Interestingly, Saimiriine herpesvirus has recently been linked to idiopathic pulmonary fibrosis [2]. All it would take is a more pathogenic strain of this virus and we would be in a lot of problems.

[1] http://en.wikipedia.org/wiki/Rhadinovirus

[2] http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4050527/