Health officials say the United States is headed for its worst year for whooping cough in five decades, with the number of cases rising at an epidemic rate. So far this year, nine children have died and doctors are calling on adults and children to get vaccinated.
Whooping cough or pertussis is a highly contagious disease that can strike people of any age but is most dangerous to children.
"Whooping cough can be deadly to infants," said Fresno Pediatrician Dr. Bill Ebbeling.
He said it's particularly deadly to children under the age of one.
Its name comes from the sound children make as they're gasping for breath. Symptoms can include congestion, fever and a prolonged severe cough that can last up to six weeks. That's why Ebbeling, as well as the California Department of Public Health, is warning adults and children to protect themselves.
"We're seeing it spreading and a lot of people get the bright idea oh I don't want my kid to have it, but it can kill children that are very young, it can give a chronic cough for weeks on end," said Ebbeling.
He said whooping cough has generally been increasing for years, but this year's spike is startling.
According to the Centers for Disease Control and Prevention, nearly 18,000 cases have been reported so far - more than twice the number seen at this time last year.
"It's a bacterial infection and the vaccine is highly effective in stopping it," said Ebbeling.
In 2010, a new law was signed by Governor Jerry Brown requiring students to get a whooping booster before they start middle and high school, but some families opted-out over concerns the vaccine wasn't safe.
Ebbeling said parents have no need to worry and recommended adults, especially pregnant women, as well as those who spend time around children also get vaccinated.
The C.D.C recommends children get vaccinated in five doses, with the first shot at 2 months and the final one between four and six years old.
A booster shot is required under California state law, for students 11 and 12 years old - unless they opt out.
If a child does not have health insurance, or is only partially insured, a doctor or local health department can provide information about the Vaccines for Children Program, which provides free or low-cost vaccines.
Local health departments are offering expanded immunization clinics next month as part of "National Immunization Awareness Month." For the most complete and up-to-date information on required vaccinations, click here .