(Portland, OR) -- With just days left to the end of the school year, Portland's Lincoln High School is grappling with an outbreak of pertussis, or whooping cough. Officials say at least 18 cases of the illness are suspected, presumed or confirmed. Cases are only officially confirmed when lab work is done and reported to health officials. Both students and staffers have become ill. The Multnomah County Health Department has sent a letter home to parents about whooping cough and advising them to make sure all family members are up to date on their immunizations.