I live in wash state. Have 2.5 mo old baby. Anything help prevent perussis? Has had 1 dtap, what else can I do til fully immunized?

Tdap for you and ALL. Yes, washington state has >1000 cases of pertussis (whooping cough) so far this year! i hope you have had your tdap and encourage all those around this child to get one (adults, grandparents...). Also keep the little one away from anyone with a cough (e.g. No church nursery, etc..) i would consider 'just staying home for a while' but your baby may have some immunity w/just one shot under his belt.
Avoid unimmunized. The first 6 months of life are critical for babies because pertussis is so deadly at that age. I would make an effort to avoid any area where those who choose not to vaccinate may be, like some day cares or church nurseries. Shopping and dining at off hours to avoid crowds is also important.By 6 mo when you have the full primary series, you can relax. (but I still avoid the unvaccinated)