It starts like a cold, with congestion and upper respiratory symptoms, and then progresses to a cough. You have fits of coughing that are so severe that you can't stop or catch your breath.

It's that severe, prolonged cough, and especially the characteristic paroxysms [uncontrolled fits] of cough that trigger physicians to be worried about pertussis and try to confirm the diagnosis.

The symptoms are pretty nonspecific, and so doctors don't always suspect it. Pertussis is high on the list if that whoop is present. The “whoop” sounds like a sharp gasping intake of breath after all the air has been coughed out of your lungs. If it's not, it's likely to go unrecognized because there aren't really other signs and symptoms that are as characteristic.

It's a bacterial infection, so it can be treated with antibiotics, usually erythromycinor a family of antibiotics like erythromycin. Erythromycin is taken for 2 weeks.

If antibiotics are recommended, they should take all the doses and finish the recommended course. It's important for a couple of reasons. If the child's doctor feels that antibiotics are necessary, it's important to take the doses on time to develop and maintain the appropriate antibiotic levels in the blood to clear the infection. And missing a dose or stopping early can sometimes result in a relapse. It's also important in general, because one of the things that promotes antibiotic resistance in bacteria is stopping and starting [antibiotics].