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A Riverside County baby has died of highly contagious whooping cough, the first such death in California since 2010, state health officials announced Friday.

The child was 2 months old and had been “sick for some time,” according to Barbara Cole, director of disease control at the Riverside County Department of Public Health.

The death was first announced by the California Department of Public Health, which warned that whooping cough epidemics peak every three to five years.

Young infants are at greatest risk for the highly contagious bacterial disease, also called pertussis, which is spread by coughing, state health officials said.

Deaths of young infants from pertussis can be prevented by pregnant women getting vaccinated during the third trimester of every pregnancy, according to the director of the California Department of Public Health, Dr. Ron Chapman.

“This baby’s death is a tragedy for the family, and for California as a community, and this is a preventable disease,” Chapman said in a news release. “When pregnant women are vaccinated, the immunity they develop against pertussis is passed to their infants and helps protect infants until they are old enough to be vaccinated themselves.”

The mother of the Riverside County infant had not been vaccinated during pregnancy, according to Cole.

During a pertussis epidemic in the state in 2010, more than 9,100 cases and 10 deaths were reported. After dropping since then, case reports began increasing again in the middle of 2013, the department stated.

Infant vaccinations start at 2 months of age but don’t adequately protect babies until they are about 6 months old, according to the department.

Whooping cough symptoms in children typically include a cough and runny nose for one to two weeks, with the cough worsening and sometimes ending in a “whooping sound,” the department stated. Younger infants may not have a cough but parents may notice their baby’s face turning red or purple.

More information about pertussis is at the CDPH website.

KTLA’s Jim Nash contributed to this article.