Bithaniya Fieseha, a high school senior, graduates from the Youth Public Health Ambassador program run by the Fairfax County Health Department at West Springfield High School in Fairfax County, Va. Will Schermerhorn/Fairfax County Health Department hide caption toggle caption Will Schermerhorn/Fairfax County Health Department Bithaniya Fieseha, a high school senior, graduates from the Youth Public Health Ambassador program run by the Fairfax County Health Department at West Springfield High School in Fairfax County, Va. Will Schermerhorn/Fairfax County Health Department Of all the things she could have done on her summer vacation, Bithaniya Fieseha, a senior at West Springfield High School in Fairfax County, Va., decided to study chronic disease, mental…