Preliminary tests identified the source of the outbreak as the highly contagious norovirus, which had struck several guests just before they boarded the cruise Nov. 3 in Rome, Carnival officials said.
the guests boarded the cruise on august 6th
( z1 board :ARG0 ( z2 guest ) :ARG1 ( z3 cruise ) :time ( z4 date-entity :month 8 :day 6 ) )