▁Fr ant , ▁Sus sex . ▁ ▁An ▁attempt ▁to ▁verify ▁the ▁effic acy ▁of ▁the ▁v acc ine ▁by ▁using ▁a ▁place bo ▁group ▁for ▁comparison ▁was ▁v eto ed ▁by ▁the ▁military ▁command ers , ▁who ▁object ed ▁to ▁the ▁experiment . ▁ ▁En orm ous ▁ant igen ic ▁variation ▁in ▁Orient ia ▁ts uts ug am ush i ▁stra ins ▁is ▁now ▁recognized , ▁and ▁imm unity ▁to ▁one ▁stra in ▁does ▁not ▁confer ▁imm unity ▁to ▁another . ▁ ▁Any ▁scr ub ▁ty ph us ▁v acc ine ▁should ▁give ▁protection ▁to ▁all ▁the ▁stra ins ▁present ▁locally , ▁to ▁give ▁an ▁acceptable ▁level ▁of ▁protection . ▁ ▁A ▁v acc ine ▁developed ▁for ▁one ▁local ity ▁may ▁not ▁be ▁protect ive ▁in ▁another , ▁because ▁of ▁ant igen ic ▁variation . ▁ ▁This ▁complexity ▁continues ▁to ▁ham per ▁efforts ▁to ▁produce ▁a ▁vi able ▁v acc ine . ▁ ▁History ▁▁ ▁Se vere ▁ep ide m ics ▁of ▁the ▁disease ▁occurred ▁among ▁troops ▁in ▁Bur ma ▁and ▁C ey lon ▁during ▁World ▁War ▁II . ▁ ▁Several ▁members ▁of ▁the ▁U . S . ▁Army ' s ▁ 5 3 0 7 th ▁Compos ite ▁Unit ▁( M err ill ' s ▁Mar aud ers ) ▁died ▁of ▁the ▁disease , ▁and ▁before ▁ 1 9 4 4 , ▁no ▁effective ▁ant ib iot ics ▁or ▁v acc ines ▁were ▁available . ▁ ▁World ▁War ▁II ▁provides ▁some ▁indic ators ▁that ▁the ▁disease ▁is ▁en demic ▁to ▁und