Kama is not karma. Karma means action - think of it as the ripples in a pond caused by your acts, bouncing back and forth causing reactions and repercussions that you may not have forseen, with various kinds of dukkha resulting. Kama is one of the causes of dukkha - Kama is lusting after sensual gratification.
So strictly speaking the Kama Sutra is the Book of Lust and from a buddhist point of view is quite an iniquitous concept.
More on dukkha in a moment.