Today, 1 December, is World Aids Day.
Every year 2.6 million people worldwide are infected with HIV.
Activists say trying to stem the spread of the virus is particularly difficult in countries where homosexuality is illegal.
This can mean that gay people are afraid to get tested for fear of arrest and that the governments of those countries do not promote safer sex for same-sex couples.
India only recently made homosexuality legal, in part to help the health campaign against Aids.
However, homosexuality remains illegal in many countries in Africa.
To discuss the law and HIV/Aids, the World Today's Lawrence Pollard brought together Dr Gitau Mburu from the International HIV/Aids Alliance in Kenya and Justice AP Shah, the Indian chief justice responsible for the de-criminalisation.
First broadcast 1 December 2010