The escalating number of whooping cough cases in California has prompted the state department of public health to declare an epidemic.

In a statement released June 13, the California Department of Public Health (CDPH) announced that the incidences of whooping cough in the state has already reached epidemic levels with nearly 3,500 cases of the contagious disease reported halfway through this year alone, more than the number of cases in 2013. The contagious bacterial disease primarily raised concern the past two weeks as California had 800 or nearly a quarter of the total number of its whooping cough cases this year.

Whooping cough, also known by its medical name pertussis, is a respiratory infection caused by Bordetella pertussis. Its symptoms include violent coughing fits characterized by a whooping sound when the patient breathes in. The disease, which primarily affects children particularly unvaccinated infants and those between 11 and 18 years old whose immunity against the disease has started to wane, can be fatal with California having two cases of pertussis-related infant deaths this year.

CDPH director Ron Chapman urged everyone to get vaccinated especially pregnant women as this would give their infants who are too young to get immunized protection against the disease and infants who are at least six weeks old. Older children and preteens should also get vaccinated as the immunity they have against the disease already starts to wear off. Adults are urged to get vaccinated as well particularly those who will be around very young infants.

"Preventing severe disease and death in infants is our highest priority," Chapman said. "We urge all pregnant women to get vaccinated. We also urge parents to vaccinate infants as soon as possible."

DTaP vaccine is given to children below seven years old while Tdap is given those who are older. Before vaccination became available, whooping cough was responsible for up to 10,000 deaths in the U.S. per year but this has now been reduced to less than 30 per year.

Still, many still refuse to get themselves and their children vaccinated. The whooping cough epidemic in California in 2010, one of the worst cases of pertussis outbreak in recent years which affected more than 9,000 and killed 10 infants, was partly due to parents who refused to get their children vaccinated, a study finds.

Parents who opted not to have their children vaccinated claimed that vaccines can cause autism and other health problems, which health experts say are scientifically unfounded.