Just like most other disease control campaigns, you appeal to people to change their behaviour, you use social control to support their choice to comply and ult

Just like most other disease control campaigns, you appeal to people to change their behaviour, you use social control to support their choice to comply and ultimately you use laws and the iron fist of the state (see smoking or leprosy as good examples). Seriously, in campaigns to minimise HIV transmission in much of the rich world, they generally use self-interest, people's feelings about their loved ones and the broader sense of social concern as drivers, and above all, non-judgemental honest information - that has worked pretty well in many places (although concern about rapid infection growth in some communities amongst young men-who-have-sex-with-men has been growing recently). Fear-based campaigning hasn't had a particularly good track record in public health campaigning, at least as far as I recall (just one statistical analysis of road-safety campaigns: http://eprints.qut.edu.au/1839/1/1839.pdf http://eprints.qut.edu.au/1839/1/1839.pdf)