The nature of disease has changed substantially.

In the first world, we have a pretty good hold on infectious disease. We no longer have to worry about a third the population being wiped out by an epidemic.

As was suggested, now we largely face lifestyle illnesses like heart disease and cancer. This is obviously a direct result of food being easier to acquire and a more sedentary style of life.

If you're like me, you prefer the second dilemma. After all, lifestyle diseases can be prevented with a healthy lifestyle. Surviving infectious disease back in the day was often a matter of luck.