manchester n.h. two republican u.s. presidential hopefuls say saturday would implement quarantine travelers necessary stop spread zika virus new jersey governor chris christie garner international attention 2014 quarantine nurse return unite state treat ebola patients say would hesitate bet would christie say debate new hampshire republican contenders white house ben carson retire neurosurgeon say use quarantine simple issue evidence zika infection spread would utilize quarantine zika virus carry mosquitoes transmit humans two suspect case sexual transmission unite state also raise question ways zika may spread virus affect large part latin american caribbean world health organization declare outbreak international health emergency feb. cite strongly suspect relationship zika infection pregnancy microcephaly condition mark abnormally small head size result developmental problems republican u.s. presidential hopefuls say zika quarantine may need