How many people worldwide have been infected with epidemic typhus?

A big killer. It has been said that epidemic typhus (rickettsia prowazekii) has killed more humans than all the wars in history. It is transmitted classical by infected clothing (body) lice and in the last century has dwindled substantially worldwide but pops up occasionally in this of strife, famine or war. A substantial outbreak occurred in burundi about 20 years ago.
Look it up. Are you looking for help with your homework? This isn't the kind of thing that most doctors memorize. We would have to look it up. And if we can, so can you. Good luck with your assignment!