June 17, 2014 -- More than 3,400 new cases of whooping cough were reported in California between January 1 and June 10, which means the outbreak is officially an epidemic, according to the state's department of health.
There have been about 350 new cases of whooping cough (pertussis) so far this year in Los Angeles County. Long Beach has been hit particularly hard, with more than 90 new cases of the bacterial disease and an infection rate of nearly 20 cases per 100,000 people, NBC News reported.
Whooping cough -- which is highly infectious and can be spread by coughing -- is cyclical and peaks every three to five years, according to the California Department of Public Health. The last major peak in cases was in 2010.
Two-thirds of the people hospitalized with whooping cough have been children four months or younger, and two infant deaths have been reported, according to the health department said.
"Preventing severe disease and death in infants is our highest priority," Dr. Ron Chapman, director of the health department, in a news release, NBC News reported. "We urge all pregnant women to get vaccinated. We also urge parents to vaccinate infants as soon as possible."