Prevalence of hepatitis C virus antibodies in a clinic-based group of Italians from one geographic area
Corresponding author and reprint requests: Pier Paolo Valcavi, Institute of Microbiology, Via Gramsci 14, 43100 Parma, Italy, Tel: +39 0521 988885 Fax: +39 0521 993620 E-mail: email@example.com
Objective: To evaluate the prevalence of anti-HCV antibodies using subjects hospitalized in surgical departments and medical wards, and out-patients; secondly, to assess the evidence for developing chronic hepatitis in subjects positive for anti-HCV when compared with those with hepatitis B virus (HBV).
Methods: 21888 serum samples from 18380 subjects were investigated for anti-HCV antibodies using second and third generation immunoenzymatic assays. Some of these subjects were hospitalized patients and some were out-patients.
Results: The study showed a 12.8% overall anti-HCV prevalence rate with significant differences between out-patients (16.5%) or subjects hospitalised in medical wards (16%) and in-patients in surgical departments (7.7%). The third group included asymptomatic subjects over twenty years old whose sera were tested for anti-HCV antibodies as part of routine preoperation screening and not on clinical suspicion. Hence, this group, too, can be considered as representative of the general population, and the prevalence of anti-HCV antibodies observed among them as the prevalence of anti-HCV antibodies in the general population in a northern Italian area. The data, following a confirmatory test (RIBA) on positive samples, were analysed for their positivity to different antigens (the simultaneous presence of antibodies to the C-100, C-33 and C-22 antigens), as an index of developing chronic viral activity. This was observed in 63.4% of positive patients from surgical departments.
Conclusions: There is a large proportion of the asymptomatic population which could be chronically infected.
Hepatitis C virus (HCV) has been recognized since 1989 as a major cause of parenterally transmitted non-A non-B hepatitis [1,2]. Primary HCV infection is asymptomatic in 90–95% of cases  and is only accidentally revealed by abnormal liver function tests and/or testing for antibodies to HCV .
Acute infections are usually benign; fulminant hepatitis is extremely rare. Despite a lower prevalence of anti-HCV antibodies compared with other viral causes of hepatitis, such as hepatitis B, infection with HCV is very likely to become chronic [5,6]. The clinical spectrum of such chronic HCV infection varies from an asymptomatic carrier status without liver damage to clinically apparent and rapidly progressive hepatitis advancing to cirrhosis in a few years [7,8]. Nevertheless, progression to cirrhosis occurs over time (20–30 years) in about 30% of cases . Surveys on the prevalence of antibodies to HCV, performed in different countries, have usually been focused on specific target populations, such as risk groups (transfused patients, intravenous drug users, patients with hemophilia or on dialysis), patients with chronic liver diseases or blood donors [10,11].
Anti-HCV prevalence has usually been shown to be relatively low among blood donors (about 1% in Europe and in North America, and 1–3% in the Middle East and Asia) , when compared with risk groups: 60–80% among hemophiliacs  or drug users, and 15% among dialysis patients . However, such groups are not representative of the general population [15,16].
The aims of this study were: first, to evaluate the prevalence of anti-HCV antibodies using a wide sample of subjects hospitalized in surgical departments, as representative of the general population of a northern Italian area, of those in medical wards and of outpatients; second, to assess the evidence for developing chronic hepatitis in subjects positive for anti-HCV compared with those with hepatitis B virus (HBV).
MATERIALS AND METHODS
Between 1993 and 1996, 21888 serum samples were tested for anti-HCV antibodies taken from 18380 subjects, 9856 females and 8524 males, among the population of Parma, northern Italy. Among these subjects, 13128 were hospitalized patients and the others were outpatients. The analyzed subjects came from three groups, according to the departments they attended: the first group comprised 7326 patients aged over 20 from surgical departments, the second group comprised 5802 patients from medical wards, and the third group comprised 5252 outpatients. Those in the second and third groups were of all ages.
All sera were screened for anti-HCV antibodies by an enzyme-linked immunosorbent assay (ELISA) (Ortho HCV ELISA Diagnostic Systems, a Johnson and Johnson company, Raritan, NJ), using a second-generation assay until March 1993 and subsequently with third-generation kits. Samples were considered reactive when their optical density values (OD) were equal to or higher than the OD value of the cut-off as indicated by the manufacturer (the cut-off value is the mean of three negative control OD values plus 0.600).
Reactive sera were then tested with a recombinant immunoblot assay (second and third generations of Chiron RIBA HCV strip immunoblot assay). The RIBA test employs the same antigens as the ELISA test, but placed as individual bands on nitrocellulose strips. According to the manufacturer's instructions, anti-HCV positivity was confirmed when two or more reactive bands were detected.
Hepatitis B surface antigen (HBsAg), antibodies to HBV core antigen (anti-HBc) and anti-HBs were assayed by Abbott Auszyme monoclonal, Corzyme and Ausab respectively. Sera positive for HBsAg were retested with a confirmatory enzyme immunoassay (EIA). Anti-HBc IgM antibodies were assayed by a microparticle enzyme immunoassay (Abbott Corzyme-M).
The chi-squared test was used for examining data derived from HCV analyses in order to determine the significance of differences in the groups analyzed. A p value of less than 0.05 was considered to have statistical significance.
The overall prevalence of anti-HCV antibodies was assayed in sera from 18380 subjects using EIA and the RIBA (Table 1). Antibodies reacting in the EIA were found in 2759 subjects; the RIBA test was performed on all these EIA positives and 2359 were confirmed, representing 12.8% of the entire population examined. The rates of anti-HCV positivity showed a statistically significant difference (p<0.01) between males (14.4%) and females (11.5%).
Table 1. Prevalence of anti-HCV antibodies in 18380 subjects of the area of Parma
Table 2 shows the data obtained from the 18380 subjects according to their different hospital departments. A statistically significant difference (p<0.01) was observed between the prevalence observed in the surgical departments (7.7%) and those in medical wards (16%) or in the outpatient group (16.5%).
Table 2. Prevalence of anti-HCV antibodies in subjects hospitalized in surgical or medical departments, or in outpatients
|General population|| || || || || || || || |
| Number of subjects||7326|| ||5802|| ||5252|| ||18380|| |
| HCV Positive||565||7.7||926||16||868||16.5||2359||12.8|
|Males|| || || || || || || || |
| Number of subjects||2944|| ||3148|| ||2432|| ||8524|| |
| HCV Positive||259||8.8||496||15.8||473||19.4||1228||14.4|
|Females|| || || || || || || || |
| Number of subjects||4382|| ||2654|| ||2820|| ||9856|| |
| HCV Positive||306||7.0||430||16.2||395||14.0||1131||11.5|
The positivity rates in the different departments were also analyzed according to sex (Table 2). No significant difference was observed in the medical wards, where positivity was 15.8% among males and 16.2% among females. In contrast, a significant difference was observed both in the outpatient group, where positivity was 19.4% among males and 14% among females (p<0.01), and in the surgical departments where positivity was 8.8% among males and 7% among females (p<0.01).
Table 3 shows that 69.7% of the HCV RIBA-positive patients showed the simultaneous presence of anti-C100p, anti-C33c and anti-C22p antibodies, whereas 30.3% were positive for only two bands. Positivity rates analyzed by department showed 63.4% in surgical departments, 69.8% in medical wards and 73.8% in the outpatient group.
Table 3. Serologic profiles observed in HCV RIBA-positive subjects hospitalized in surgical departments or medical wards, and in outpatients
|Number of subjects||565|| ||926|| ||868|| ||2359|| |
|Three bands RIBA positive (C100p, C33c, C22p)||358||63.4||646||69.8||641||73.8||1645||69.7|
|Two bands RIBA positive||207||36.6||280||30.2||227||26.2||714||30.3|
A comparison between HBV and HCV infections was performed on the basis of the antibody prevalence and of serologic markers for developing chronic infection.
We compared the prevalences of HBV and HCV antibodies in a subgroup of 13598 sera, taken from the main group of 18380 subjects, on whom both analyses had been done.
Table 4 shows that the prevalence of anti-HCV antibodies in this study subgroup was 12.3% versus 26.3% for anti-HBc antibodies. A lower prevalence of anti-HCV antibodies than of anti-core antibodies was found in the patients from surgical departments (7.5% for HCV versus 25.2% for HBV), in the medical wards (15.2% HCV versus 30.5% HBV) and in the outpatient group (15.9% HCV versus 23.5% HBV).
Table 4. Presence of anti-HCV and anti-HBV (HBcAb) antibodies in 13598 subjects hospitalized in surgical departments or medical wards, and in outpatients
|Number of subjects||5473|| ||4022|| ||4103|| ||13598|| |
For 15313 subjects, also belonging to the main group of 18380 subjects, both anti-HCV antibodies and HBsAg were required. In this group we compared the percentage of subjects showing the simultaneous presence of anti-C100p, anti-C33c and anti-C22p antibodies to the percentage of subjects showing persistence of HBsAg in the serum (or the presence of both HBsAg and anti-HBc antibodies in the absence of anti-HBc IgM and anti-HBs) in order to estimate the tendency for each virus infection to become chronic (Table 5).
Table 5. Comparison between percentages of HCV RIBA-positive and HBsAg-positive subjects in 15313 subjects hospitalized in surgical departments or in medical wards, or in outpatients
|Number of subjects||6449|| ||4587|| ||4277|| ||15313|| |
|HCV RIBA+ C100p+, C33c+, C22p+||290||4.5||413||9.0||473||11.1||1176||7.7|
It was found that 7.7% of the sera were simultaneously positive for antibodies to all three antigens (C100p, C22p and C33c) of HCV and 2% of the sera showed markers of HBV persistent infection. The percentage of sera ‘persistently’ positive for HBsAg in each group of analyzed subjects was lower than the percentage of sera simultaneously positive for anti-C100p, anti-C22p and anti-C33c antibodies. Moreover, 17 of 1176 subjects who were anti-C100p, anti-C33c and anti-C22p positive were also ‘persistently’ positive for HBsAg, representing 1.4% of the HCV-positive population (data not shown in Table 5).
We report here the results of a 3-year seroepidemiologic investigation into HCV infection in a large group of subjects. The overall prevalence of anti-HCV antibodies was evaluated in a population which included subjects hospitalized in surgical departments or in medical wards or who were outpatients, and was found to be 12.8%. This agrees with the percentage positive for HCV infection found in Italy generally .
Previous reports have indicated that HCV infection occurs in Italy more frequently in men than in women . Our results confirm this at a significant level (p<0.01). Consequently, the differences observed in our surgical departments, as well as in the outpatient group, reflect those in the general population. In the outpatient group, in particular, the higher percentage of positive subjects among males than among females could be due to males being investigated on clinical suspicion more often than females, while women were often screened before or during pregnancy.
Grouping the subjects by their different hospital departments showed a significant difference in anti-HCV antibody prevalence between subjects from surgical departments and those from medical wards or outpatients. Those in surgical departments were, by definition, aged over 20 and were tested as part of routine preoperative screening even if they were asymptomatic. Thus these subjects can be considered to be representative of an asymptomatic general adult population with various possible routes of contact with HCV. This population differs from blood donors as well as from any risk group, which are the target populations usually chosen for analysis. In these surgical patients. HCV positivity was 7.7% and, among these, 63.4% were positive for three bands.
Three important aspects of HCV progression to chronic infection are widely accepted in the literature. First, it occurs in 50–80% of cases [5,19]; second, the simultaneous presence of antibodies to C100p C33c and C22p HCV antigens correlates closely with the presence of virus in the blood ; and, third, the simultaneous presence of three positive bands can be considered to be evidence of a greater risk of developing chronic infection .
These results, from surgical patients, allow us to suggest that there is a large number of asymptomatic but probably chronically infected subjects in our population.
The comparison between HBV and HCV infections, in the population studied, by assessing both antibody prevalence and markers for a higher risk of chronic infection confirm the finding, by the Italian National Surveillance System for Acute Viral Hepatitis (SEIEVA), that the prevalence of antibodies to HBV is higher than that of antibodies to HCV  while, in contrast, the frequency of serologic markers indicating a trend towards chronicity is higher for HCV than for HBV infection.
The authors thank G. Araldi, F. Dadà, G. Favagrossa and E. Pesci for technical assistance.
This research was supported by grants from the Ministero dell'Università e della Ricerca Scientifica e Tecnologica (MURST), FIN ‘97, and from MURST, FIL ‘97.