john hollmann reports from san salvador. >> reporter: soon to be mothers in a hospital in el salvadorworrying about the same thing, the zika virus. it's spreading fast here, transmitted by mosquitos. scientists think if the mother is infected, it could cause brain damage to the unboard child. the link is yet to be proved, but el salvador's government has already taken the extraordinary step of warning wyoming not to get pregnant for at least the next year. that's too late for christ abell who is suffering from the fever and rash that come with zika she is sick with worry. >> i wouldn't have got pregnant. i would really have waited for the outbreak to have finished. >> reporter: the vice minister of health says this is just the tip of the iceberg. authorities only recently detected the virus here, but they are already getting ready for the brain-damaged children they think could be born in around seven months' time. >> we started to discuss this, to look at what special resources the system needs to give support to these children, looking at other countries who have had the problem to

john hollmann, al jazeera, san salvador. monday, iowa will be the first u.s.tate where each no thoughts it's candidate. for months, presidential hopefuls have spent millions of dollars wooing iowa voters because a win there can make or break their campaign but with a population of less than 3 million people, why many are asking why iowa is so important, from des moines. kim by the wayly halkett explains. >> you better get your bread out. >> in hoilz like this the united states will host its first official votes in the presidential nominating contest. when are is this caucus going to be held? >> to caucus means to gather. you won't see polling booths. 3 medical people became problemnant in the united states election cycle through historical accident. >> in 1972, there were a series of changes to select their nominee to be president of the united states and iowa happened to go first that year. so, iowa has been first ever since. passing out clips of paper for you to vote on. >> the republican caucus is simple, supporters vote by secret bal objection tossed in a