system
Given the following post, respond as if you're commenting on Reddit:
human
Is it known what caused the current monkeypox outbreak?

Do scientists and medical experts know what has caused the current monkeypox outbreak? Have there been mutations which have caused it to spread so widely? Was there a superspreader event that's causing it to snowball? Have changes to society made it more likely that a disease such as this will infect more people? Something else?

Thanks!
gpt
It’s not really known why monkeypox is spreading exactly *now*, but it's presumably a combination of factors:

* Increased population susceptibility. Smallpox vaccination protects against monkeypox, but since smallpox vaccination stopped an increasing proportion of the population is susceptible to monkeypox; and even smallpox immunity from the vaccine gradually wanes. This is probably the most important overall factor
* Increased global connectivity. Monkeypox outbreaks have been happening for decades if not centuries, but it's not a highly transmissible disease, and in a small local community it will burn out fairly quickly. Today's communities are generally not small or local, so there are more opportunities for the virus to keep spreading
* Entering a highly connected community that offers specific chances for this virus's transmission, in the MSM community. 

You can think of it as a situation where for hundreds of years, sparks have been jumping into piles of leaves. Most sparks just burn a leaf or two, and die out. Even if the flames spread to a neighboring few leaves, if the piles are small and well separated, the fire will never get too big. Even a big pile of leaves won't burn easily, if it's soaking wet (smallpox vaccination). 

But for the past couple decades, the leaf piles have been getting bigger and bigger, and drier and drier. Finally, several sparks have set off long term, persistent fires. 

(Note that there are multiple transmission chains being identified -- it's likely that once the right conditions were reached, several sparks were able to set off fires.)

There's no evidence that there are transmssion-enhancing mutations. While the circulating viruses do have more mutations than you'd expect, these mutations don't seem to be beneficial -- they're the result of human defenses that drive lethal mutation in viruses. You can think of the mutations as scars, evidence that the viruses have been circulating in humans for some time, but not enhancing that circulation.