It only shows up in the animated YouTube videos, and Brain thinks it's a joke due to the high lethality rate.

As increased liberty allowed for it, a more regulated form of duel was conceived: The modern Mensur, which strived to reduce lethality rates while still being able to fence.

Some suicide methods have higher rates of lethality than others; e.g. wrist-slashing has a much lower lethality rate than use of firearms, which results in death 90% of the time.

There is no basis for assuming that an H5N1 pandemic will emerge with only the far lower 1-2% lethality rate of the Spanish Flu, once assumed to be a worst case scenario.