daryl efron: whooping cough is caused by a really nasty bacteria called bordetella pertussis, and it produces a toxin and it attacks the airways and causes a really nasty bronchitis. and they get really sticky, thick phlegm that they can't shift, and they try to, and that causes them to cough. (baby coughing) and the cough needs to be really, really vigorous, but they often... it's not very effective and then sometimes they stop breathing. and if they stop breathing for long enough, they go red in the face at first and then sometimes, if it's an extended period of not breathing, they can go blue, and that can be very, very frightening. (baby coughing) narrator: half of all infants younger than one will be hospitalized. about one in 100 dies. (monitor beeping) antibiotics can reduce the chance of infecting others, but there is no cure. osman's tiny body must fight the illness. a generation ago, whooping cough was rarely seen in developed countries. now it's back. in 2012 there were nearly 50,000 cases in the u.s. and 20 deaths. babies too young to get the pertussis shot may have no pr