The graph above shows the cases and deaths due to HIV/AIDS per year for the USA.

What we can see from the graph is that there have been dramatic shifts in the trends of annual HIV infections and AIDS deaths in USA since the disease was first diagnosed.

There was initially a growth in both cases and deaths following a typical epidemic curve: slowly at first then with growing momentum to a peak in 1992 for infections and 1995 for AIDS deaths. Then there is a sharp fall in both curves. The number of infections falls steeply from about 80,000 to plateau at about 40,000 by 2000.

This fall in the number of infections is believed to be due to changing behaviour, especially among homosexual men, the largest infected group in USA, and also the increasing availability of drugs, and the ability to buy them, to control the effects of infection.

The fall in the number of AIDS deaths is of course related to the number of infections, and is a lagged response, with a peak some 3-4 years later, reflecting the potentially relatively long incubation period of the virus. In addition, however, the number of AIDS deaths continue to fall rather than plateauing after 2000, with a widening gap between infections and deaths. This is due to the effect of ARVs.

The effects of the new ARV drug therapies are apparent. These are prolonging the lives of those affected, adding years of life with the infection rather than preventing the infection or preventing death as a direct result of the infection.