A third baby has died of whooping cough in Los Angeles County, bringing the total to six deaths this year in California.
Health officials on Tuesday did not immediately have further details about the death.
Whooping cough has become an epidemic in California, which has recorded about 1,500 cases through July 13. That's a fivefold increase over the same period last year.
The five previous deaths involved Latino babies under 3 months of age who were too young to be immunized.
Jonathan Fielding, the county's health director, urges parents and caretakers to get vaccinations to avoid any more deaths.
A typical case may appear similar to a common cold for up to two weeks, followed by weeks or months of coughing fits that sometimes end with a whooping sound.
Copyright 2010 The Associated Press.