▁involved ▁in ▁border ▁control ▁and ▁disease ▁monitoring . ▁ ▁International ▁convent ions ▁ 1 8 5 2 – 1 9 2 7 ▁Since ▁ 1 8 5 2 ▁several ▁con ferences ▁were ▁held ▁involving ▁European ▁powers , ▁with ▁a ▁view ▁to ▁uniform ▁action ▁in ▁keeping ▁out ▁in fection ▁from ▁the ▁East ▁and ▁prevent ing ▁its ▁spread ▁within ▁Europe . ▁All ▁but ▁that ▁of ▁ 1 8 9 7 ▁were ▁concerned ▁with ▁ch ol era . ▁No ▁result ▁came ▁of ▁those ▁at ▁Paris ▁( 1 8 5 2 ), ▁Constantin ople ▁( 1 8 6 6 ), ▁Vienna ▁( 1 8 7 4 ), ▁and ▁Rome ▁( 1 8 8 5 ), ▁but ▁each ▁of ▁the ▁subsequent ▁ones ▁doctrine ▁of ▁construct ive ▁in fection ▁of ▁a ▁ship ▁as ▁coming ▁from ▁a ▁scheduled ▁port , ▁and ▁an ▁approximation ▁to ▁the ▁principles ▁advoc ated ▁by ▁Great ▁Britain ▁for ▁many ▁years . ▁The ▁principal ▁countries ▁which ▁retained ▁the ▁old ▁system ▁at ▁the ▁time ▁were ▁Spain , ▁Portugal , ▁Turkey , ▁Greece ▁and ▁Russia ▁( the ▁British ▁poss essions ▁at ▁the ▁time , ▁Gib ral tar , ▁Mal ta ▁and ▁Cy pr us , ▁being ▁under ▁the ▁same ▁influence ). ▁The ▁aim ▁of ▁each ▁international ▁san it ary ▁convention ▁had ▁been ▁to ▁bind ▁the ▁govern ments ▁to ▁a ▁uniform ▁minimum ▁of ▁prevent ive ▁action , ▁with ▁further ▁restrictions ▁perm iss ible ▁to ▁individual ▁countries . ▁The ▁minimum ▁specified ▁by ▁international ▁convent ions ▁was ▁very ▁nearly ▁the ▁same ▁as ▁the ▁British ▁practice , ▁which ▁had ▁been ▁in ▁turn ▁adapted