State health officials say 1,100 new cases of pertussis, or whooping cough, have been reported in the past two weeks.
The number of cases reported in California is now 4,558. The total already exceeds last year's number of 2,532.
In Fresno County, 265 cases have been reported, an increase from the 121 reported in May. In 2013, 41 cases were reported in the county. Three children have died in California from the disease.
Whooping cough is a cyclical respirtory disease that tends to spike every three to five years, said David Luchini, assistant director of the Fresno County Department of Public Health. The last spike in the disease happened in 2010, where one person in Fresno County died.
Symptoms of the disease vary by age. For children, symptoms include a runny nose and cough that can last up to two weeks. For adults, pertusis may be a cough that lasts for several weeks.
People can avoid whooping cough by getting vaccinated.
"Pregnant women should get vaccinated in the third trimester to avoid whooping cough in newborns," Luchini said.
If adults are suffering from a cough for more than a week, health officials recommend that they see a doctor.
The reporter can be reached at email@example.com or @SharonBMartin on Twitter.