The bacterium Bordetella pertussis causes pertussis. It is spread easily through droplets in the air from coughing or sneezing by an infected person. Anyone can catch pertussis and spread it.
Children can also catch pertussis by touching toys or objects handled by an infected person, and then rubbing their eyes or mouths. The pertussis-causing bacteria can live for two to five days on dry objects like clothes, glass or paper.
Pertussis is most contagious during the first two weeks after coughing starts. If you get treatment, you are no longer infectious after five days.