According to the Department of Public Health, doctors were slow to diagnose pertussis in all eight cases, despite several visits to clinics or hospitals.
"You can't always tell. A child could come in with a runny nose, a little cough and a tiny fever, it could be a lot of things," said Dr. Jonathan Fielding, director for the Department of Public Health for Los Angeles County. "What we are saying now is that we want those who are seeing these children to think pertussis. We know that early treatment with antibiotics can be life saving."
This is the worst year for whooping cough in California since 1958. There have been 3,600 reported cases. That's a 700 percent increase over the same period last year.
In the eight deadly cases, the infant was initially treated for a nasal condition or a mild upper respiratory infection. By the time the accurate diagnosis was made it was too late.
"It is really unsettling. I think that it is one of those things you just have to hope for the best," said Sara Chester of West Los Angeles.
"Medicine in itself is always guess work," said April Vicchrilli of Burbank. "The doctors are doing their best work to determine what it is, but it is not always right."
Whooping cough is highly contagious. While children often contract an illness from other kids at school or daycare a majority of pertussis cases are being transmitted from a child's older sibling or their parents. Doctors recommend parents build a wall of immunity at home.
"Those immunizations are lifesaving. They are really important," said Dr. Fielding. "I hope every parent understands the importance of not only getting them, but getting them on time for their children."
Health officials are also encouraging new mothers and family members who have close contact with infants to get the adult version of the whooping cough vaccine.
The Associated Press contributed to this report.
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