title: Monophyletic outbreak of Hepatitis A involving HIV-infected men who have sex with men, Rome, Italy 2008-2009.
abstract: BACKGROUND
  Outbreaks of Acute Hepatitis A Virus (HAV) among men who have sex with men (MSM) have been reported in Europe and, recently, in Italy. From July 2008 through January 2010, 162 HAV infections were diagnosed at National Institute for Infectious Diseases, Rome, Italy, with high male-to-female ratio (M:F=7.5).
  
  
  OBJECTIVE
  The aim of this study was to characterize viral strains involved in this outbreak.
  
  
  METHODS
  The sequences of VP1-2A junction of HAV genome, obtained from 67/97 HAV-RNA-positive samples, were used for phylogenetic analysis.
  
  
  RESULTS
  All but 1 of the HAV sequences were genotype 1A, 1 was genotype 1B. A monophyletic cluster, including 59/66 genotype IA sequences, was identified by phylogenetic analysis. This cluster included also 2 HAV strains isolated in Germany (2007) and France (2008) from MSM, that, in turn, were reported to be genetically correlated to HAV strains circulating in Tuscany in 2008. Among the males harboring an HAV strain belonging to the cluster, 62% reported to be MSM, and 25% were HIV-positive, 2 with acute HIV infection.
  
  
  CONCLUSIONS
  The outbreak occurred in Rome in 2008-2010, involving high proportion of HIV-infected MSM, is sustained by a monophyletic HAV strain, circulating around the same period also in other European countries. Possible factors favouring HAV spread among HIV-infected persons, such as high risk behavior and prolonged fecal excretion, need to be further elucidated. Timely identification of outbreaks with one or the same source of infection may be helpful to implement preventive measures addressing at risk populations.
authors.affiliation: Laboratory of Virology, National Institute for Infectious Diseases 'L. Spallanzani', 292 Via Portuense, Rome, Italy.
authors.forename: Licia
authors.initials: L
authors.lastname: Bordi
authors.forename: Gabriella
authors.initials: G
authors.lastname: Rozera
authors.forename: Paola
authors.initials: P
authors.lastname: Scognamiglio
authors.forename: Claudia
authors.initials: C
authors.lastname: Minosse
authors.forename: Mariarosaria
authors.initials: M
authors.lastname: Loffredo
authors.forename: Andrea
authors.initials: A
authors.lastname: Antinori
authors.forename: Pasquale
authors.initials: P
authors.lastname: Narciso
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Ippolito
authors.forename: Enrico
authors.initials: E
authors.lastname: Girardi
authors.forename: Maria Rosaria
authors.initials: MR
authors.lastname: Capobianchi
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016000:Cluster Analysis; D004196:Disease Outbreaks; D005260:Female; D015658:HIV Infections / Q000150:complications*; D006506:Hepatitis A / Q000453:epidemiology*; D030041:Hepatitis A virus / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D018451:Homosexuality, Male; D006801:Humans; D008297:Male; D008875:Middle Aged; D017720:Molecular Epidemiology; D008969:Molecular Sequence Data; D010802:Phylogeny; D012367:RNA, Viral / Q000235:genetics; D012384:Rome / Q000453:epidemiology; D017422:Sequence Analysis, DNA; D055815:Young Adult
chemical_list: D012367:RNA, Viral