No worries....they are probably after the sweet stuff that aphids excrete. They are on my Jostaberry after the few aphids that are on the blackcurrant related shrub. Ants do no harm while exploring after aphids.

They do protect and tend the aphids, though, which may allow the aphids to multiply to harmful levels. As a first try, I would leave lots of spearmint leaves--not stems!--around the bushes to repel the ants. Ground up orange or tangerine peel sometimes works, too.

Get rid of the aphids and you get rid of the ants - blast them off with the hose, or use ECO friendly washing up liquid, a squirt in a sprayer with water (don't use ordinary washing up liquid though). Or put a rubber glove on and rub them off with your fingers.