An outbreak of hepatitis A virus infection with a high case-fatality rate among injecting drug users.
OBJECTIVE
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 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.


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 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.


CONCLUSIONS
HAV 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.
Spada
Enea
E
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
Genovese
Domenico
D
Tosti
Maria Elena
ME
Mariano
Andrea
A
Cuccuini
Marco
M
Proietti
Laura
L
Giuli
Cinzia Di
CD
Lavagna
Alessandro
A
Crapa
Giuseppe Edoardo
GE
Morace
Graziella
G
Taffon
Stefania
S
Mele
Alfonso
A
Rezza
Giovanni
G
Rapicetta
Maria
M
D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D015897:Comorbidity; D004196:Disease Outbreaks; D005260:Female; D005838:Genotype; D015658:HIV Infections / Q000453:epidemiology; D006506:Hepatitis A / Q000453:epidemiology* / Q000401:mortality / Q000635:transmission; D030041:Hepatitis A virus / Q000235:genetics* / Q000302:isolation & purification; D006509:Hepatitis B / Q000453:epidemiology; D006526:Hepatitis C / Q000453:epidemiology; D006801:Humans; D007558:Italy / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D015819:Substance Abuse, Intravenous / Q000453:epidemiology* / Q000401:mortality