required in england, which has the safest egg supply in europe. investigators in the u.s. are still trying to figure out where the outbreak started. here s steve osunsami. reporter: already more than 1,200 people have gotten sick. scientists from cdc told abc news tens of thousands more could get sick from contaminated eggs. this is a large outbreak, there s no doubt about that. it compares to some of the bigger outbreaks we would have seen due to this type of organism back in the 1980s and 90s. reporter: the cdc predicts the vast majority of cases will go unreported. one in five who get sick from this strain will need to be hospitalized. scientists haven t yet figured out the source of the contamination but have identified infected hens that have been laying infected eggs, which includes the yolk and egg whites inside. health officials say exposure to salmonella from an infected egg can happen instantly. when you touch or crack open an egg, for example, and it gets on your hand