TOW (& Answer)...

The question was: What was one of the most severe recorded epidemics of bubonic plague?  The answer is the Persian Plague of 1772-73.  This outbreak killed an estimated two million people in Persia & Persian controlled lands to the west.

The question (& answer) were found on p. 239 of The Encyclopedia of Plague and Pestilence edited by George C. Kohn and published by Facts on File, Inc. in 1995.