(Portland, OR)  --  Parents are being warned, after a case of pertussis, also known as whooping cough, was confirmed at Clinton Kelly Elementary School in Southeast Portland.  KATU-TV reports it brings the number of whooping-cough cases in the area this year to nine.  The Multnomah County Health Department says pertussis is more of a nuisance for healthy adults, but it can be dangerous for younger individuals.  Officials say vaccination is the best protection against it.