▁in ▁some ▁cases , ▁officials ▁tried ▁to ▁v acc inate ▁n atives ▁only ▁to ▁discover ▁that ▁the ▁disease ▁was ▁too ▁w ides p read ▁to ▁stop . ▁At ▁other ▁times , ▁trade ▁dem ands ▁led ▁to ▁broken ▁quar ant ines . ▁In ▁other ▁cases , ▁n atives ▁refused ▁v acc ination ▁because ▁of ▁susp icion ▁of ▁whites . ▁The ▁first ▁international ▁health care ▁expedition ▁in ▁history ▁was ▁the ▁Bal mis ▁expedition ▁which ▁had ▁the ▁aim ▁of ▁v acc in ating ▁ind igen ous ▁pe op les ▁against ▁small po x ▁all ▁along ▁the ▁Spanish ▁Empire ▁in ▁ 1 8 0 3 . ▁In ▁ 1 8 3 1 , ▁government ▁officials ▁v acc in ated ▁the ▁Y ank ton ▁Si oux ▁at ▁Si oux ▁Agency . ▁The ▁S ante e ▁Si oux ▁refused ▁v acc ination ▁and ▁many ▁died . ▁ ▁De pop ulation ▁from ▁European ▁Con quest ▁ ▁War ▁and ▁violence ▁ ▁While ▁ep ide mic ▁disease ▁was ▁a ▁leading ▁factor ▁of ▁the ▁population ▁decl ine ▁of ▁the ▁American ▁ind igen ous ▁pe op les ▁after ▁ 1 4 9 2 , ▁there ▁were ▁other ▁contrib uting ▁factors , ▁all ▁of ▁them ▁related ▁to ▁European ▁contact ▁and ▁colon ization . ▁One ▁of ▁these ▁factors ▁was ▁war fare . ▁According ▁to ▁dem ograph er ▁Russell ▁Thor nt on , ▁although ▁many ▁lives ▁were ▁lost ▁in ▁wars ▁over ▁the ▁centuries , ▁and ▁war ▁sometimes ▁contributed ▁to ▁the ▁near ▁ext inction ▁of ▁certain ▁tribes , ▁war fare ▁and ▁death ▁by ▁other ▁violent ▁means ▁was ▁a