system
Given the following post, respond as if you're commenting on Reddit:
human
It seems that infectious diseases that kill too quickly never have a chance to spread. How often are people the first and only (or among very few) to die of a novel but short lived infectious disease?
gpt
There are several avian influenza viruses that have a high mortality rate in humans, but that transmit very poorly between humans.  Viruses like H5N1, H5N6, H7N9 have killed thousands of people worldwide, each time because of a direct contact with an infected bird. 

However, the lack of transmission is probably not because the virus kills too quickly, but more because of the way it infects. It’s believed that these viruses are much better at infecting deep in the lungs than in the nose and throat, so on the one hand they cause severe pneumonia and lung damage, but on the other they don’t shed large amounts of virus in outgoing breaths.