Whooping cough epidemic spreading in California

A whooping cough epidemic is spreading throughout California.

More cases have been reported in the first five months of the year than all of 2013. From Jan. 1 to May 27, 2,649 cases of pertussis were reported, California Department of Public Health officials said.

Falling numbers of immunizations, lessening immunity and a more aggressive detection of the cough may be contributing to the rise, the San Jose Mercury News reports.

Whooping cough is a highly contagious bacterial disease that starts with cold-like symptoms and leads to coughing fits. Infants too young to be vaccinated are at the greatest risk of contracting it.

The Associated Press contributed to this report.