[The AIDS epidemic in Norway--where did it go?]

The 1986 prognosis for the AIDS-epidemic in Norway has not been fulfilled. The epidemic has been far less extensive than anticipated. In 1986, little knowledge existed about the parameters that influence the spread of the human immunodeficiency virus (HIV): the prevalence of HIV, the HIV transmission rate, the duration of the infectious period and the extent of risk behaviour. The prognosis was therefore not reliable. The causes of the variability in HIV transmission and in the duration of the infectious period are still poorly understood and thus cannot be easily influenced. A reduction of risk behaviour among homosexual men has been observed. In the general population there has been a slight increase in use of condoms. The behavioural changes may express HIV-preventive measures. However, the large discrepancy between the early HIV/AIDS prognosis and the observed epidemic in Norway cannot be explained by behavioural change alone.