Background/Aims: In 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...
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Background/Aims: In 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. Methods: We conducted an epidemiological investigation, including a case-control study, to identify the source and themodes of HAV transmission. Hepatitis B and C (HCV) viruses and human immunodeficiency vir us (HIV) coinfections were clinically analysed. Sequence analysis of the VP1/2A junction of the HAV isolates was also performed. Results: Of 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 i nterval: 1.3-29.9). Of the cases, 58%were anti-HCV positive and 4.7%anti-HI V positive. Three individuals died of acute liver failure: 2 were HCV-coinfecte d alcohol abusers, with underlying liver cirrhosis; 1 was HCV/HIV-coinfected. H AV-RNA was found in 15 of the 24 tested patients: genotype IB (8 cases) and III A (7 cases) were detected. Conclusions: HAV was probably transmitted through the fecal-oral route, although parenteral transmission cannot be excluded. The hig h fatality ratewas probably due to severe underlying liver damage. The occurrenc e of this outbreak highlights the need for routine HAV vaccination for IDUs.
Background and aims: Cellular mediated immunity (CMI) is thought to play a key role in resolution of primary hepatitis C virus (HCV) infection. However, CD4+and CD8+T cell responses are also generated during acute inf...
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Background and aims: Cellular mediated immunity (CMI) is thought to play a key role in resolution of primary hepatitis C virus (HCV) infection. However, CD4+and CD8+T cell responses are also generated during acute infection in individuals who become chronic, suggesting that they developed a defective CMI. The aim of this study was to verify if and when such immune dysfunction is established by measuring the breadth, magnitude, function, and duration of CMI in a large cohort of subjects during the natural course of acute HCV infection. Methods: CMI was comprehensively studied by prospective sampling of 31 HCV acutely infected subjects enrolled at the onset of infection and followed for a median period of one year. Results: Our results indicated that while at the onset of acute HCV infection a measurable CMI with effector function was detected in the majority of subjects, after approximately six months less than 10%of chronically infected individuals displayed significant CMI compared with 70%of subjects who cleared the virus. We showed that progressive disappearance of HCV specific T cells from the peripheral blood of chronic patients was due to an impaired ability to proliferate that could be rescued in vitro by concomitant exposure to interleukin 2 and the antigen. Conclusion: Our data provide evidence of strong and multispecific T cell responses with a sustained ability to proliferate in response to antigen stimulation as reliable pharmacodynamic measures of a protective CMI during acute infection, and suggest that early impairment of proliferation may contribute to loss of T cell response and chronic HCV persistence.
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