Since the first reported case of AIDS 27
years ago, more than 70 million people have
been infected with HIV worldwide, and 25
million have died of AIDS. The Joint United
Nations Programme on HIV/AIDS (UNAIDS)
estimates that 33 million people are currently
living with HIV. The global prevalence
of HIV has leveled off, but the total number
of people living with HIV continues to grow.1
This article briefly discusses the roles
that different HIV transmission modes play
in the worldwide pandemic, and explains
how the global pandemic is actually a complex
mosaic of dynamic epidemics within
and between countries.2 Further, it discusses
matching appropriate prevention
responses to two different types of epidemics:
generalized and concentrated.
