The second stage of pertussis includes uncontrolled coughing spells followed by a whooping noise when a person breathes in. During these severe coughing spells, a person may vomit, or their lips or face may look blue from a lack of oxygen. Between coughing spells, a person may appear well. This stage may last four to six weeks. Pertussis in these groups may seem more like a cold with a cough that may last a long time.
Pertussis can occur at any age, but is most common in children in the first year of life.
Infants and young children usually get the disease from an older brother or sister or an adult who may have a mild illness. The bacteria which cause pertussis are found in the mouths, noses, and throats of infected people. The bacteria are spread in the air by droplets produced during sneezing or coughing. Once a person is exposed by inhaling these droplets, it takes seven to ten days before the first symptoms appear. Pertussis is very contagious during the early stage of the illness and becomes less contagious by the end of three weeks.