It could spread from other places where it exists. Syria would be the most likely source given its geographic proximity.
Alternatively, there are vaccines that use a semi-disabled live virus. While normally harmless, in war with lots of opportunities for transmission and many many people with weakened immune systems, it is possible for it to mutate back into the dangerous form of the virus. This was known to happen in the US in the last few years.
One thing I don’t understand is, how can polio resurface after 24 years?
I am tempted to think that it was intentionally released, but perhaps someone has a less evil explanation?
It could spread from other places where it exists. Syria would be the most likely source given its geographic proximity.
Alternatively, there are vaccines that use a semi-disabled live virus. While normally harmless, in war with lots of opportunities for transmission and many many people with weakened immune systems, it is possible for it to mutate back into the dangerous form of the virus. This was known to happen in the US in the last few years.