Pertussis (whooping cough) is caused by the Bordetella pertussis bacteria. Pertussis cases occur every year, with epidemics occurring approximately every 3-5 years in communities around the country. Given that the most recent California epidemics occurred in 2010 and 2014, a new epidemic seems likely to occur in the near future. Pertussis rates began to increase in Orange County at the end of the last school year in spring before decreasing during the summer months. Orange County Public Health (OCPH) will be monitoring pertussis rates closely in the coming months to see if rates increase again with school restarting.