Umatilla County health officials on Wednesday confirmed that a child in the western end of the county has been diagnosed with pertussis.
Pertussis, also known as whooping cough, is a contagious respiratory infection that can last for weeks, and is known for coughing spasms with accompanied by a "whooping" sound, although not all people experience that.
Other symptoms include sore throat, runny nose and vomiting after coughing.
The Umatilla County child had attended school before being diagnosed. Family members were given antibiotics to prevent further spread of the illness.
Health officials encouraged residents to get immunized against pertussis, even adults who may have gotten a pertussis shot as a child.
"The best protection against pertussis is immunizing with DTaP or Tdap vaccines," said Genni Lehnert-Beers, the county's public health administrator. "It's important to know that immunizations do not always provide 100 percent protection against disease for everyone, especially if more than five years has elapsed since the last shot."
Other preventive measures include staying home when sick, coughing into a tissue or elbow, keeping hands away from the face or mouth, and regular hand-washing.
This is the first confirmed case of pertussis in Umatilla County since 2009, officials said.