▁b acter ia ▁and ▁are ▁the ▁only ▁type ▁of ▁t icks ▁shown ▁to ▁transmit ▁L yme ▁disease ▁b acter ia ▁to ▁humans . ▁ ▁Other ▁species ▁are ▁carried ▁by ▁soft ▁t icks . ▁The ▁soft ▁tick ▁Or n ith odor os ▁car ries ▁the ▁species ▁of ▁Bor ell ia ▁that ▁cause ▁rela ps ing ▁fe ver . ▁Another ▁species , ▁B . ▁an ser ina , ▁is ▁carried ▁by ▁the ▁soft ▁tick ▁Arg as . ▁Inside ▁the ▁t icks , ▁the ▁b acter ia ▁grow ▁in ▁the ▁mid g ut ▁and ▁then ▁travel ▁to ▁the ▁sal iv ary ▁g lands ▁to ▁be ▁transm itted ▁to ▁a ▁new ▁host . ▁T icks ▁can ▁spread ▁the ▁b acter ia ▁to ▁each ▁other ▁when ▁co - feed ing . ▁If ▁an ▁animal ▁has ▁been ▁inf ected ▁by ▁a ▁tick ▁and ▁then ▁is ▁bit ten ▁by ▁a ▁second ▁tick , ▁the ▁second ▁tick ▁can ▁become ▁inf ected . ▁The ▁b acter ia ▁are ▁most ▁commonly ▁transm itted ▁to ▁humans ▁through ▁t icks ▁in ▁the ▁n ym ph ▁stage ▁of ▁development , ▁because ▁they ▁are ▁smaller ▁and ▁less ▁likely ▁to ▁be ▁noticed ▁and ▁removed . ▁The ▁t icks ▁must ▁have ▁around ▁ 3 6 ▁to ▁ 4 8 ▁hours ▁of ▁contact ▁with ▁a ▁host ▁to ▁successfully ▁transmit ▁the ▁b acter ia . ▁▁ ▁L ice ▁▁ ▁L ice ▁that ▁feed ▁on ▁inf ected ▁humans ▁ac quire ▁the ▁Bor rel ia ▁organ isms ▁that ▁then ▁multiply ▁in ▁the ▁hem ol ym ph ▁and ▁gut ▁of ▁the ▁l ice .