HIV/AIDS in Europe : the link between surveillance and prevention

HIV infection continues to be a heavy burden in Europe with, in 2011, nearly 1 million people living with HIV in western and central Europe and 1.4 million in eastern Europe. Public health surveillance has provided key information for setting up prevention programmes and for healthcare planning. The objectives of this thesis are to contribute to the development of HIV/AIDS surveillance in Europe and to analyse HIV epidemiological trends in Europe and to discuss their implications for public health. The work is based primarily on a selection of published papers which analysed European HIV/AIDS surveillance data until 2006. The European HIV/AIDS surveillance system covers all 53 countries of the WHO European Region; it initially relied solely on the reporting of AIDS diagnoses and progressively evolved to include new HIV diagnoses as well as data from HIV prevalence surveys. The discussion has been further elaborated in the context of the state of knowledge at the end of 2012. The papers show that there are several concurrent, interrelated HIV epidemics across the WHO European region. In western Europe, the advent of combination antiretroviral therapy (cART) in 1996 resulted in decreased emphasis on HIV prevention and a resurgence of high-risk behaviours among men having sex with men (MSM), which was followed a few years later by a rise in new HIV diagnoses in this population. Heterosexual migrants from sub-Saharan Africa significantly contributed to the HIV burden in western Europe although the number of HIV diagnoses in this migrant population has been declining since the mid-2000, which can be related with the decline in HIV incidence in Africa since the late 1990s. Numbers of HIV infections reported among injecting drug users (IDU) have been declining steadily since the 1990s even though a large HIV outbreak among IDU was reported in one country in 2011. MSM constitute the most affected population by HIV across countries in western and central Europe since the middle of the first decade of this century. Central and eastern Europe have been initially isolated from the global HIV pandemic but HIV infection has later spread very differently in each of the two regions. In central Europe, the HIV epidemic remained a low-level one. In eastern Europe, a severe epidemic rapidly developed, primarily associated with injecting drug use, but increasingly involving heterosexual transmissions. The epidemic among MSM remained hidden with few HIV cases being officially reported in this population. Unlike in western Europe, where AIDS cases have been declining since the advent of cART, in eastern Europe, the number of AIDS cases has been continuously increasing, due to late diagnosis and delayed initiation of treatment. In the European Union, an estimated 30% of HIV infected persons have not been diagnosed and nearly 50% are diagnosed late. In eastern Europe, it is estimated that more than 50% of HIV infected persons have not be diagnosed and that only 25% of HIV infected persons are receiving cART. Scenario simulations suggested that the number of infectious individuals and the number of deaths could be reduced by several folds if all HIV infected persons were diagnosed and if the availability of cART was similar to that in western Europe. The main limitations of the currently available surveillance tools is that they do not provide direct measures of HIV prevalence and HIV incidence, the two statistical measures of the burden and scope of the HIV epidemic. Despite the use of common case definitions and standardised format, heterogeneity in the meaning of some of the variables reported constitutes a limitation of the European HIV/AIDS surveillance system. The European HIV/AIDS surveillance system has been a catalyst for adopting better methodologies and improving national surveillance. The data generated have allowed meaningful international comparisons and benchmarking, and have been widely used for advocacy and for informing prevention. The extent to which these data have contributed to developing and evaluating prevention is however difficult to assess because the public health decision making process is a complex process and is not always documented, and because there is no repository documenting the range of activities and coverage of HIV prevention programmes. In the light of the now demonstrated evidence that early cART can effectively impact HIV transmission at the population level, the thesis stresses the need for raising awareness about HIV, for educating people about the benefits of early testing and treatment, and for improved risk assessment and recognition of HIV infection by healthcare providers. It also stresses the continuing importance of behavioural interventions to prevent HIV risk behaviours, in particular among MSM, and of harm reduction to prevent HIV transmission through drug use. In eastern Europe, large scale prevention programmes and increased cART provision are urgently needed. The thesis makes recommendations for future developments in surveillance including improving standardisation of surveillance definitions and practices, development of better methods for estimating HIV incidence, implementation of behavioural surveillance among high-risk populations across European countries, and production of national estimates of HIV prevalence. The link between surveillance, public health, research, and communities should be improved and efforts made to monitor prevention programmes and activities and to evaluate the effectiveness of public health interventions.