I'm not sure that the marketing in South Africa has been very effective. I would suggest a strategy similar to something I saw in the Uk (for road safety). It showed a woman driving in her car, crashed, and her son, sitting behind her, smashed his head against the back of hers, killing them both. The point is, if you risk death, the way to spread the message is in a serious (and shocking) a manner as you possibly can. Let's face it - by not responding to the message you risk killing other people. Is it possible to overexaggerate the message?
And you do so by showing reality at its grittiest. Another campaign could show people in the final stages of AIDS - skeletal, gaunt, suffering. That's the consequence of infection, of infecting, and not knowing.