25-fold per subsequent year. The prevalence of non-B subtypes in Italy was first estimated in a 2001 study which reported an overall prevalence of 5.4% among drug-naïve patients, with an increasing trend over time [7]. Two later studies reported higher prevalences of 12.6 and 10.7% in regions Wnt inhibitor review with

low/medium and high incidences of infection, respectively [25,26]. Both these figures, although showing an increase in non-B prevalence over time, are lower than those reported in this work, as well as in surveillance studies carried out in other European countries such as France, Belgium and the United Kingdom [8,9,11]. According to several studies, the spread of non-B subtypes is highly dependent upon several

variables that define the demographics of local HIV-1 epidemics and their evolution over time. The proportions of patients of non-Caucasian ethnicity and those infected via the heterosexual route increased in our case file throughout the study period. However, we also detected a higher prevalence of non-B variants in European individuals after 1992, with a 5-fold increase being found in the proportion of patients with non-B variants compared with the earlier period. As expected, the regression analysis indicated a strong association between the African ethnicity and the carriage of non-B strains. ITF2357 cost However, Thymidylate synthase 50% of individuals infected with strains other than B were Caucasian, suggesting that these strains have been onward-transmitted to Europeans at a considerable rate. Overall, an increase in the prevalence of non-B strains was seen in all risk categories; however, the most relevant increase was found in heterosexuals. The multivariable analysis performed on the patient subset with CD showed that the heterosexual route of infection was a strong independent predictor of HIV-1 infection with non-B clades, a 9.5-fold higher risk of carriage of non-B infection being

found for heterosexuals. Probably because of the local characteristics of the HIV-1 epidemic, such as the high proportion of women among IDUs, the male to female ratio was comparable between the period before 1993 and the period from 1993 onwards (2.25 vs. 2.32, respectively), and female gender was not an independent predictor of non-B infection. Nevertheless, women with non-B variants represented a sizeable proportion (almost one-third) of the total number of women diagnosed after 1992. Finally, the evaluation of time of HIV-1 diagnosis clearly indicated that the risk of acquiring non-B infection was 4-fold higher for those diagnosed after 1993 as compared with previous years. High heterogeneity in group M non-B clades was detected in our study, indicating that the sources of non-B infection were dispersed world-wide.