Nine cases of pertussis, or whooping cough, have now been confirmed in Skagit County and health investigators are looking at additional possible cases.
At this time, the cases do not appear to be linked to any specific school or other public gathering place.
"Whooping cough is most dangerous for babies," Skagit County Public Health said in a news release. "About half of babies younger than one year who get the disease need care in the hospital."
The illness can cause a baby's breathing to pause.
Early symptoms include runny nose, low grade fever and a mild cough.
As the illness progresses patients can experience coughing fits, coughing that ends in a high pitched "whoop" or gasp, vomiting and exhaustion.
Public Health is urging you to make sure you're vaccinated against the illness. If you suspect you have whooping cough, contact your health care providers.