PREVALENCE, RISK-FACTORS, AND GENOTYPE DISTRIBUTION OF HEPATITIS-C VIRUS-INFECTION IN THE GENERAL-POPULATION - A COMMUNITY-BASED SURVEY IN SOUTHERN ITALY

In 1996 the prevalence, risk factors, and genotype distribution of hep atitis C virus (HCV) infection were assessed in the general population of a town in southern Italy, The sample was selected from the census by a systematic 1:4 sampling procedure, The participation rate was 96. 6%. Among the 1,352 subjects enrolled, 195 (14.4%) tested reactive to antibody to HCV (anti-HCV) with enzyme immunoassay (EIA 3), When furth er tested with recombinant immunoblot assay (RIBA 3), 170 subjects (87 .2%) tested positive, 23 subjects (11.8%) had indeterminate results, a nd 2 subjects (1%) tested negative. Thus, the overall anti-HCV EIA-pos itive RIBA-confirmed prevalence was 12.6% (170 of 1,352 subjects) and increased from 1.3% in subjects younger than 30 years to 33.1% in thos e greater than or equal to 60 years of age, This latter age group acco unted for 72.3% of all anti-HCV-positive subjects. Females tested posi tive more frequently than males (14.1% vs, 10.5%; P <.05). Alanine tra nsaminase (ALT) concentrations were abnormal in only 4.1% (7/170) of a nti-HCV EIA-positive RIBA-confirmed subjects, This suggests that ALT s creening is not useful in the detection of anti-HCV-positive subjects in a general population, The results of multiple logistic regression a nalysis showed that an age of less than 45 years, the use of glass syr inges, and dental therapy were all independent predictors of anti-HCV positivity, HCV RNA was detected by polymerase chain reaction in 75.9% of the 195 anti-HCV EIA-positive subjects: in 84.7% (144/170) of the RIBA-confirmed subjects; in 17.4% (4/23) tested as RIBA indeterminate; and in neither of the two subjects who tested RIBA negative, HCV type 1b was detected in 75 subjects (50.7%), type 2b in 1 subject (0.7%), type 2c in 66 subjects (44.6%), type 3a in 4 subjects (2.7%), and type 4 in two subjects (1.3%). These figures differ from those of Italian patients with chronic liver disease in whom genotype 2 is more rare, N one of the individuals was infected with more than one genotype, The d istribution of the two most common HCV viral types (1b and 2c) was not statistically different in terms of mean age, sex, or risk factors an d suggests that they may have had a parallel spread in this community. These findings provide one of the highest overall anti-HCV prevalence rates in a general population with a likely cohort effect, i.e., decr eased risk of infection along generations, These observations may indi cate an epidemic or focus of hepatitis C that occurred several years e arlier, The majority of anti-HCV-positive subjects in the oldest age g roup and with no clinical evidence suggests that HCV infection is a ve ry prolonged and indolent disease.