Participants at a world Aids conference in Mexico are calling on Iran to release from detention two doctors known for their pioneering work on HIV/AIDS.
Human rights groups have claimed the two brothers, Arash and Kamiar Alaei, have been imprisoned.
Aids has long been a taboo topic in Iran, where the stigma of the virus makes it difficult for people to seek treatment.
But as Ali Reza Ronaghi reports things are starting to change.
