▁among ▁Canadian ▁children ▁under ▁ 1 4 ▁until ▁the ▁mid - 1 9 2 0 s . ▁In ▁Ontario ▁alone , ▁ 3 6 , 0 0 0 ▁children ▁died ▁from ▁di ph ther ia ▁between ▁ 1 8 8 0 ▁and ▁ 1 9 2 9 . ▁Research ▁at ▁the ▁end ▁of ▁the ▁ 1 9 th ▁century , ▁not ably ▁involving ▁Pierre ▁Paul ▁É mile ▁R oux ▁and ▁Alexandre ▁Y ers in ▁of ▁the ▁P aste ur ▁Institute ▁as ▁well ▁as ▁Emil ▁von ▁Be hr ing ▁and ▁K itas ato ▁Sh ib as ab ur ō , ▁had ▁p aved ▁the ▁way ▁for ▁di ph ther ia ▁ant ito x in ▁production ▁using ▁horses . ▁The ▁ant ito x in ▁could ▁save ▁lives ▁when ▁given ▁early ▁enough ▁in ▁the ▁course ▁of ▁the ▁disease , ▁and ▁in ▁large ▁enough ▁dos es . ▁Despite ▁the ▁develop ments , ▁treatment ▁was ▁often ▁too ▁cost ly ▁for ▁middle ▁class ▁families ▁since ▁Canadian ▁public ▁health ▁efforts ▁to ▁counter ▁the ▁spread ▁of ▁di ph ther ia ▁were ▁largely ▁dependent ▁upon ▁expensive ▁imports ▁from ▁commercial ▁U . S . ▁fir ms . ▁ ▁In ▁ 1 9 1 3 , ▁John ▁G . ▁Fitz G er ald ▁took ▁up ▁a ▁new ▁role ▁as ▁part - time ▁Associ ate ▁Professor ▁of ▁H yg iene ▁at ▁the ▁University ▁of ▁Toronto . ▁After ▁becoming ▁one ▁of ▁the ▁young est ▁gradu ates ▁of ▁the ▁University ▁of ▁Toronto ▁Medical ▁School ▁in ▁ 1 9 0 3 , ▁he ▁had ▁spent ▁a ▁de cade