A case of whooping cough, also known as pertussis, had been confirmed at Beaverton High School.
Beaverton High School principal Anne Erwin says one student has a confirmed case of whooping cough, but is recovering.
County health authorities are working with the school, and administrators sent home a letter in both English and Spanish, warning parents and staff about the case.
The Centers for Disease Control and Prevention call pertussis a very contagious disease. Infected people are most contagious up to about 2 weeks after the cough begins, though antibiotics may shorten that time.
The serious respiratory infection is marked by violent, seemingly unstoppable coughing.
Whooping cough is most harmful for young babies and can be deadly, the CDC said.