Croatia: still a low-level HIV epidemic?--seroprevalence study

Central Europe is a region with a low prevalence of infection with human immunodeficiency virus (HIV). Until the end of 2007, 663 HIV cases were recorded in Croatia, almost exclusively among most at-risk populations. The aim of this research was to determine the HIV prevalence among most at-risk populations and the level of the HIV epidemic in Croatia. According to the World Health Organization classification there are three levels of HIV epidemics: generalized (prevalence in general population > 1%), concentrated (prevalence in general population < 1% and prevalence in at least one of the most at-risk populations > 5%) and low-level epidemic (prevalence in general population < 1% and prevalence in each most at-risk population < 5%). This was a research with convenience samples of most at-risk populations. The respondents were recruited by their peers, all non-governmental organizations that provide services for most at-risk populations and the researchers. Sera were tested using the fourth generation enzyme-linked fluorescent assay (EIA test) and reactive test were confirmed using the Western Blot test. In this research, the highest HIV prevalence was found within the men who have sex with men group (7/232 = 3%, 95% CI = 1.3-6.3%) and commercial sex workers (1/70 = 1.4%, 95% CI = 1-7.8%). In these samples we were unable to determine whether Croatia is facing a low-level epidemic due to the fact that the prevalences were not statistically significantly lower than 5% (p = 0.115 and p = 0.1, respectively). For the remaining samples the prevalence was statistically significantly lower than 5%, which points to a low-level epidemic. The prevalences in these samples were 7/593 = 1.2% (95% CI = 0.5-2.4%) in people with more than two sexual partners within the last 12 months, 2/249 = 0.8% (95% CI = 0-2.9%) in people with sexually transmitted infections in history, 2/317 = 0.6% (95% CI = 0-2.2%) in clients of sexual workers, 2/323 = 0.6% (95% CI = 0-2.2%) in injecting drug users and 0.2% (95% CI = 0-1%) in the sample of migrant workers. Based on the results of this survey, Croatia would be classified as having a low-level HIV epidemic although the confidence limits in two most-at-risk groups, men who have sex with men and commercial sex workers, overlap 5%.