LOS ANGELES (CBSLA.com) — It’s a sound no parent wants to hear — a child with whooping cough struggling to breathe.

KNX1070’s Mike Landa reports the number of whooping cough cases statewide increased to more than 1,600 last year — that’s 600 more cases than in 2012.

READ MORE: Jokic Has 49, Triple-Double As Nuggets Edge Clippers In OT

The illness, also known as Pertussis, is a highly contagious, bacterial infection that gives young children uncontrollable coughing fits. Patients often make a deep “whooping” sound when they inhale.

READ MORE: Lakers Blow Halftime Lead In Loss To Pacers

Epidemiologists say whooping cough is on the rise because fewer kids are being vaccinated. California allows parents to exempt their children from public school immunization requirements.

MORE NEWS: Grandmother Carrying Infant Allegedly Assaulted By Unhoused Woman In Venice

But a new state law says parents must submit a doctor’s note, not just personal objections.