Trends of HIV infections using the anonymous mandatory reporting system and other data sources in Switzerland and in the Federal Republic of Germany.

In Switzerland and in the Federal Republic of Germany the reporting of HIV infections is based on an anonymous mandatory reporting system for laboratories. In Switzerland, physicians have to complete a questionnaire on the patient's clinical status and risk behaviour. To make a rough estimate of the prevalence of HIV infections in the general population at low risk, data on blood donations are used in both countries. In Switzerland, additional data with information on positive and negative test results have been obtained since 1985 from anonymous test sites. In both countries, the data do not show evidence of an increasing incidence of HIV infection. The number of positive test results reported by the laboratories and physicians remains stable, and the rates of HIV-positive blood donations are declining. In the Federal Republic of Germany, homo-/bisexual men play the most important role in the epidemic, whilst in Switzerland, injecting drug users contribute most to the burden of HIV infection, and the proportion of persons probably heterosexually infected is increasing steadily. Possible selection biases need to be further discussed.