EPIDEMIC: a virus / disease spread across a large community, population or region.
PANDEMIC: an epidemic spread across multiple countries and / or continents.
There is no photo for me to base this off of in your question, but here’s my answer.
Due to over population in the 20th century (over 6 billion people more then the earths capacity rate) it’s not surprising an epidemic has grown to a world wide pandemic. Not to mention travel has become much more accessible with new technologies and motor vehicles, so as the first case of i.e. corona was found in China, it eventually travelled to Europe and then to the US due to excessive traveling.
