The number of whooping cough cases in the Los Angeles area and throughout California has reached epidemic proportions, state health officials said Friday.
The California Department of Public Health said in a statement released Friday that more than 800 cases of whooping cough, also known as pertussis, have been reported over the past two weeks. As of June 10, there have been 3,458 cases -- more than in all of 2013.
CBS Los Angeles and KNX 1070 news radio report health officials say more than 85 percent of those who have contracted pertussis had preventative shots.
"The vaccine, while it's very effective when it's obtained following the first year, each year thereafter, the effectiveness decreases," said Dr. Wilma Wooten with San Diego County Health and Human Services. "That's why we're seeing the infections."
However, the number of overall pertussis cases would increase dramatically statewide if fewer people had been vaccinated, Wooten added.
Whooping cough begins with cold-like symptoms and can progress to severe coughing fits.
The infection is cyclical and peaks every three to five years. In 2010, a whooping cough epidemic killed 10 infants in the state.
Infants are most susceptible to the disease, so parents are encouraged to vaccinate their children as soon as possible. This year, two infant deaths have been reported in the state.
Nationwide, the Centers for Disease Control and Prevention says nearly 10,000 cases of whooping cough have been reported this year.