Recent Acquired STD and the Use of HAART in the Italian Cohort of Naive for Antiretrovirals (I.Co.N.A): Analysis of the Incidence of Newly Acquired Hepatitis B Infection and Syphilis P. Cicconi, A. Cozzi-lepri, G. Orlando, A. Matteelli, E. Girardi, A. Degli Esposti, C. Moioli, G. Rizzardini, A. Chiodera, G. Ballardini, C. Tincati, A. d’Arminio Monforte for the I.Co.N.A. Study Group Abstract Objective: To estimate the incidence of newly acquired syphilis (n-syphilis) and hepatitis B infection (n-hepatitis B) in I.Co.N.A. and to evaluate the impact of HAART, calendar date and risk group. Methods: Cohort study: Incidence was calculated by per- son–years analyses. Poisson regression was used for the multivariate model. Results: The rate of n-syphilis was 23.4/1,000 PYFU and it increased over time; HIV transmission risk was the most important predictor: men who have sex with men (MSM) had a considerable higher risk (RR 5.92, 95% CI 2.95–12.13 vs IDU/exIDU, p < 0.0001). The rate of n-hepatitis B was 12.2/ 1,000 PYFU; it declined in recent years and halved per 10 years age. Patients with HIV-RNA < 500 copies/ml had a 60% reduced risk of n-hepatitis B if they were treated with HAART compared with not treated individuals. Conclusions: In our population, the use of HAART was not associated with a higher risk of newly acquired sexually transmitted diseases (STD). Suppressive HAART was asso- ciated with a lower risk of HbsAg seroconversion. Incidence of n-hepatitis B has recently been declining possibly due to herd immunity provided by vaccination policies. The risk of acquiring n-syphilis has increased over time and it is higher in the population of MSM compared with other categories of HIV exposure. Infection 2008; 36: 46–53 DOI 10.1007/s15010-007-6300-z Introduction Several studies suggest that an increase in the incidence of sexually transmitted diseases (STD) has occurred in industrialized countries in recent years, especially among men who have sex with men (MSM). This increase appears to parallel an increase in sexual behaviors at risk that were recorded during the same time period in a number of behavioral surveys [1–5]. A possible explanation for this increase is that the introduction of highly active antiretroviral therapy (HA- ART) may have encouraged a more optimistic attitude toward the risk of acquiring HIV infection. HIV-unin- fected people may perceive the disease as less severe and may not be concerned about infection; on the other hand, patients treated with HAART may feel that they are not likely to transmit HIV [6–12]. Conflicting results [12–16] are provided by studies analyzing the association between HAART and sexual behaviors. Other factors, which have been operating at population level in concomitance with the introduction of HAART, may have a role in increasing the rate of sexual practices at risk. These include: sex-seeking on Internet, the higher opportunity of meeting sexual partners in P. Cicconi (corresponding author), A. d’Arminio Monforte, C. Tincati, Clinic of Infectious and Tropical Diseases, Dept. of Medicine Surgery and Dentistry, University of Milan, San Paolo Hospital, Via Rudinì, 8, 20142 Milan, Italy; Phone: (+39/02) 8184-3061, Fax: -3054 e-mail: paola.cicconi@unimi.it A. Cozzi-lepri Dept. of Primary Care and Population Sciences, Royal Free and University College Medical School, London, UK G. Orlando II Div. Infectious Diseases H. Luigi Sacco, Milan, Italy A. Matteelli Clinic of Infectious and Tropical Diseases, University of Brescia, Brescia, Italy E. Girardi INMI L Spallanzani, Rome, Italy A. Degli Esposti Dept. of Infectious Diseases H S. Annunziata, Florence, Italy C. Moioli Dept. Infectious Diseases H. Niguarda, Milan, Italy G. Rizzardini I Div Infectious Diseases H. Luigi Sacco, Milan, Italy A. Chiodera Dept. of Infectious Diseases H. Macerata, Macerata, Italy G. Ballardini Dept. of Infectious Diseases H S. Maria Delle Croci, Ravenna, Italy Received: October 26, 2006 Æ Revision accepted: August 15, 2007 Published online: January 29, 2008 Infection Clinical and Epidemiological Study 46 Infection 36 Æ 2008 Æ No. 1 Ó URBAN &VOGEL