Why was eradicating smallpox a worldwide effort? what other diseases have been controlled?

Eradicating smallpox was successful because of many reasons.

Explanation:

Smallpox was regularly found in an area or we can say it was prevalent in some places. So, mortality rates were high. It was caused by variola virus and affected mainly humans. So, it was essential that such vaccine is developed which can successfully immune people from this disease.  

Smallpox vaccine then started spreading across "Europe and North America" and then gradually it spread all over the world and successfully eradicated smallpox by 1980. Other diseases that have been controlled by vaccines are “diphtheria, bacterial influenza, measles, mumps, rubella, and tetanus”.

chapter i -- paris: september, 1792

a surging, seething, murmuring crowd of beings that are human only in name, for to the eye and ear they seem naught but savage creatures, animated by vile passions and by the lust of vengeance and of hate.

during the greater part of the day the guillotine had been kept busy at its ghastly work: all that france had boasted of in the past centuries, of ancient names, and blue blood, had paid toll to her desire for liberty and for fraternity.

hope this answer you: )!