Sammendrag
The HIV/AIDS epidemic that evolved hidden until 1981 has since then challenged different disciplines in the medical and behavioural sciences. Surveillance of AIDS was started early in many countries. Studies of HIV disease development, prevention and treatment and also vaccine studies have been carried out. Statistical models have been widely used and new developments have appeared. In this study data from HIV and AIDS registers in Denmark, Norway and Sweden was used to estimate quantitative measures of the epidemics applying different types of statistical models. In addition data on HIV prevention policies and the reaction to the HIV threat among groups with risk activity was gathered from the three countries. A special study of the effectiveness of highly active antiretroviral treatment introduced in August 1996 in Norway was also conducted.
A back calculation model is a tool to estimate new HIV infections (absolute rates) over time based on HIV and AIDS registry information. In this thesis a back calculation model was adjusted to fit the data from the HIV and AIDS registries in the Scandinavian countries. Results for men infected through sex with men and intravenous drug users showed that the epidemics developed differently within a frame of a common epidemic picture – increase, decrease and stabilisation of new cases. The HIV epidemics among men having sex with men started earlier in Denmark than in Norway and Sweden. Incidence rates were higher in Denmark than in the two other countries for a long period through the eighties. The prevalence was also higher in Denmark for the whole study period through 1995. HIV among intravenous drug users was introduced earlier in Denmark than in Norway and Sweden, but the peak of the epidemics occurred in 1985/86 in all three countries. From 1991 to 1996 Norway and Sweden had significantly lower incidence rates than Denmark. Prevalence was higher in Norway in the period 1984/85 to 1991/92 than in the two other countries.
Countries have adopted different strategies to prevent the transmission of HIV among intravenous drug users. Legal access to needles and syringes/needle exchange programmes as part of such a strategy has been heavily debated. HIV counselling and testing has also been part of prevention strategies. Sweden and Norway, with higher levels of HIV counselling and testing than Denmark, had significantly lower incidence rates of HIV among intravenous drug users 1991-1996 than Denmark where there was legal access to drug injection equipment and a lower level of HIV counselling and testing. Further investigations among intravenous drug users are necessary before concluding that the effects of HIV testing and counselling is better than legal access to drug injection equipment to keep HIV at a low level. But HIV counselling and testing should be advocated in countries where such efforts are lacking or have a low priority.
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