The Pasadena Public Health Department Health announced it is investigating an outbreak of whooping cough involving three confirmed cases at Blair Middle School.
The Los Angeles County of Public Health urges the public to get pertussis vaccinations as whooping-cough activity has increased in the county.
The number of whooping cough cases in California has reached epidemic proportions with more cases diagnosed by June than all of last year.
More cases of whooping cough have been reported in the first five months of the year than all of 2013.