As students head back to school, health departments are working with school districts to get the word out about an epidemic -- whooping cough.
Letters were sent out this summer reminding families to get their child vaccinated.
With kids heading back to school, the state health department is urging kids and adults to get their TDAP shots.
The latest numbers from the Washington State Health Department show there's 3,911 cases of whooping cough, or pertussis, in the state this year -- and 117 new cases since last week. At the same time last year there were only 387 cases in Washington.
Click here for more whooping cough facts
And the age groups that are seeing the highest rate of cases, babies under a year old and kids ages 10 - 13.
Healthcare workers are warning parents that the disease is highly contagious and spreads easily by sneezing and coughing.
"It's particularly serious if you're an infant and you don't have an immunity. It's important for anyone who can be vaccinated to be vaccinated,” said Rita Mell with the Snohomish County Health District’s Immunization Program.
Mell says expect the number of whooping cough cases to go up as kids head back into the classroom. She recommends parents call their doctors to make sure their child and themselves are up to date with their shots.