Dr. Mark Horton, director of the California Department of Public Health (CDPH) is urging Californians to get vaccinated now.He warned that the state is on pace to suffer the most illnesses and deaths due to pertussis, also known as whooping cough, in 50 years.

“Whooping cough is now an epidemic in California,” Horton said. “Children should be vaccinated against the disease and parents, family members and caregivers of infants need a booster shot.”

As of June 15, California had recorded 910 cases of pertussis, a four-fold increase from the same period last year when 219 cases were recorded. Five infants — all under three months of age — have died from the disease this year. In addition, 600 more possible cases of pertussis are being investigated by local health departments.

Pertussis is cyclical. Cases tend to peak every two to five years. In 2005, California recorded 3,182 cases and eight deaths.

Pertussis is a highly contagious disease. Unimmunized or incompletely immunized young infants are particularly vulnerable. Since 1998, more than 80 percent of the infants in California who have died from pertussis have been Hispanic.

The pertussis vaccine is safe for children and adults. Pertussis vaccination begins at two months of age, but young infants are not adequately protected until the initial series of three shots is complete at 6 months of age. The series of shots that most children receive wears off by the time they finish middle school. Neither vaccination nor illness from pertussis provides lifetime immunity.

Pregnant women may be vaccinated against pertussis before pregnancy, during pregnancy or after giving birth. Fathers may be vaccinated at any time, but preferably before the birth of their baby. CDPH encourages birthing hospitals to implement policies to vaccinate new mothers and fathers before sending newborns home. CDPH is providing vaccine free of charge to hospitals.

Others who may have contact with infants, including family members, healthcare workers, and childcare workers, should also be vaccinated. Individuals should contact their regular health care provider or local health department to inquire about pertussis vaccination.

A typical case of pertussis in children and adults starts with a cough and runny nose for one-to-two weeks, followed by weeks to months of rapid coughing fits that sometimes end with a whooping sound. Fever is rare.