California reports 1,100 new pertussis cases in past two weeks
The total number of pertussis cases so far this year now stands at 4,558, which far surpasses the 2013 total of 2,532.
The CDPH also said that another infant has died, bringing the total to three so far this year.
"Infants are at the greatest risk of illness and death from pertussis," Ron Chapman, the director of the CDPH, said. "Vaccination is the best form of protection. We're encouraging all parents to vaccinate their children, and for pregnant women to be vaccinated to protect their babies. This will ensure maximum protection against this potentially fatal disease."
Children four months of age or younger represent approximately two thirds of all pertussis hospitalizations.
"It's particularly important that people who will be around newborns also be vaccinated," Chapman said. "This includes babysitters, older siblings, parents and grandparents. When those people are vaccinated they will help protect infants who are too young for immunization."
Pertussis symptoms vary by age. For children, the sickness typically starts with a cough or runny nose that can last up for up to two weeks.
Rates of pertussis have increased in the U.S. since the 1980s, with more than 24,000 cases reported in 2013.