Pertussis, also known as whooping cough, is a highly contagious bacterial infection that causes violent coughing. The coughing makes it hard to breathe and produces a deep "whooping" sound.
Pertussis is caused by the Bordetella pertussis or Bordetella parapertussis bacteria. Droplets of the bacteria move through the air when an infected person sneezes, coughs or talks. This is how pertussis spreads from person to person.
Pertussis can occur at any age. Serious illness is most common in infants and young children. Older children, adolescents and adults usually have milder symptoms.
The number of pertussis cases in the United States has increased in recent years. There were more than 17,000 reported cases of pertussis in 2009.