After 910 cases of whooping cough that have left five babies dead, California has officially declared the outbreak an epidemic. If that isn't bad enough, the case load is 400 percent higher this year than last, putting the state on track to break a 50-year record. With an additional 600 pertussis cases currently under investigation, officials believe things are about to get worse. Those most at risk? Unimmunized or incompletely immunized babies, whose lungs are still developing.