LOS ANGELES (AP) — California did not suffer a single death from whooping cough in 2011, the first year since 1991 that there have been no fatalities in the state from the highly contagious illness, health officials said Tuesday.

The news comes after the state experienced a whooping cough epidemic in 2010 when 9,000 were infected. Most vulnerable to the disease are infants too young to be fully immunized. Ten babies died after exposure from adults or older children.

Cases of whooping cough, also known as pertussis, dropped to 3,000 last year and authorities were waiting to see how this year goes before declaring the epidemic over.

"Everything seems to indicate we're heading in that direction," said state epidemiologist Dr. Gil Chavez.

Public health officials credited the decline to greater awareness, faster diagnosis and a new state law requiring that middle and high school students get a booster shot before starting school.

At the peak of the epidemic, doctors were urged to spot whooping cough early, send infected babies to the hospital and promptly treat those diagnosed.

"We worked very hard on that and I think it was successful," said pediatrician Dr. James Cherry of the University of California, Los Angeles.

The California Department of Public Health also gave out free vaccines to hospitals and aired public service announcements in English and Spanish.

"People rallied and got vaccinated and it made a huge difference," Chavez said.

Whooping cough cases tend to run in cycles, peaking every five years. It is a highly contagious bacterial disease that in rare cases can be fatal. Whooping cough starts off like a cold but leads to severe coughing that can last for weeks.

A 2009 study in the journal Pediatrics found that children who don't get vaccinated against whooping cough are 23 times more likely to get the disease than vaccinated kids.

Among those vaccinated, authorities recommend a booster shot for older children and teens to guard against the vaccine wearing off.