evererything aut bernie sanders' victory is dependent on new voters and so is donald trump's and depending if those show up it goes in two different directions. >> thanks very much. we're going to have full coverage here at abc news this weweek on sday morning, "gma" and "world news" both live in iowa and all the results live monday night and next saturday >> a lot coming up. >>> we turn to that other big story we've been following, the zika virus, boston reporting its first case of the disease. now more than 30 detected in the u.s. and take a look at this map. you see the outbreak originating in south america and moving north. abc's dr. richard besser is at ground zero this morning in brazil to answer some important questions. good morning,rich. >> good morning, robin. you know, when you walk around the streets of rio you don't get any sense there's something going on here of such big health concern, but when you talk to pregnant women, you get a very different picture. we came to brazil, the center of the zika epidemic. the government here spraying the streets. we met fabiola already exp