• Enea Spada, Domenico Genovese, Maria Elena Tosti, Andrea Mariano, Marco Cuccuini, Laura Proietti, Cinzia Di Giuli, Alessandro Lavagna, Giuseppe Edoardo Crapa, Graziella Morace, Stefania Taffon, Alfonso Mele, Giovanni Rezza, and Maria Rapicetta.
• Istituto Superiore di Sanità, National Center of Epidemiology, Surveillance and Health Promotion, Clinical Epidemiology Unit, Viale Regina Elena 299, 00161 Rome, Italy. spada@iss.it
• J. Hepatol. 2005 Dec 1; 43 (6): 958-64.

Background/AimsIn 2002, the first reported outbreak of hepatitis A virus (HAV) infection involving mostly intravenous drug users (IDU) occurred in Italy. We attempted a thorough evaluation of the outbreak, including epidemiological, clinical and virological analyses.MethodsWe conducted an epidemiological investigation, including a case-control study, to identify the source and the modes of HAV transmission. Hepatitis B and C (HCV) viruses and human immunodeficiency virus (HIV) coinfections were clinically analysed. Sequence analysis of the VP1/2A junction of the HAV isolates was also performed.ResultsOf the 47 symptomatic cases, 35 were IDUs. The only associated risk factor was contact (not related to injecting practices) with a jaundiced person (odds ratio: 5.8; 95% confidence interval: 1.3-29.9). Of the cases, 58% were anti-HCV positive and 4.7% anti-HIV positive. Three individuals died of acute liver failure: 2 were HCV-coinfected alcohol abusers, with underlying liver cirrhosis; 1 was HCV/HIV-coinfected. HAV-RNA was found in 15 of the 24 tested patients: genotype IB (8 cases) and IIIA (7 cases) were detected.ConclusionsHAV was probably transmitted through the fecal-oral route, although parenteral transmission cannot be excluded. The high fatality rate was probably due to severe underlying liver damage. The occurrence of this outbreak highlights the need for routine HAV vaccination for IDUs.

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