Antibody to hepatitis C virus in risk groups in Canada

The prevalence of antibodies against hepatitis C virus (HCV) was studied in hemophiliacs, hemodialysis patients, intravenous drug abusers, female prisoners, homosexuals, individuals with no markers of recent hepatitis A or B virus infections and normal individuals (federal public servants), by an enzyme immunoassay (Ortho Diagnostic Systems Inc). Repeat positive samples were further tested by recombinant immunoblot assay (riba) HCV (Chiron Corp, California). The number of samples positive for antibodies to HCV (anti-HCV) was higher with enzyme immunoassay than by riba HCV in most cases. A high prevalence of anti-HCV was detected in hemophiliacs by both enzyme immunoassay (68.8%) and riba HCV (53.7%). Among intravenous drug abusers and female prisoners the prevalence rates for anti-HCV were 42.8% and 29.8%, respectively, by riba HCV; the results with enzyme immunoassay were only slightly higher. The prevalence rate was also high by both tests (54.2%) in hemodialysis patients' sera taken during 1980-82, when many cases of non-A,non-B hepatitis were suspected in this group. In contrast, only 14.1% of sera taken during 1990 were positive by riba HCV. In individuals with no markers of recent hepatitis A or B infections, 13.4% were positive by enzyme immunoassay, whereas only 4.5% were reactive by riba HCV. The lowest prevalence was seen in homosexuals (2.3%) and normal individuals (1.2%) by riba HCV. These results indicate a high prevalence of anti-HCV in high risk groups tested in Canada.

C Ll I CAL CASES OF POST TRANSFUSION HEPATITIS WITHOUT serological evidence of infection with h epatitis A. B. cytomegalovirus or Epstein-Barr vir us .were unW recently considered by exclusion to be non-A.non-Bhepatitis (1).Publication of viral markers found fo r one of the non-A.non-8agents which h as been designated hepatitis C virus (HCV), have changed the p ictu re.It is now known tl1at hepatitis C cases a r e not only associated with transfus ion, but spo radjc cases accou nt for 10 to 25% of all adult hepatitis patients (2).HCV infection has also been reported in hemodialysis patients (3).drug addicts (4).hemophiliacs (5) and persons accidentally inoculated with contaminated needles.Forty to 50% of patients infected with HCV may become chronic carriers (6) and develop cirrhosis (7).While the ability to detect infection witl1 HCV is encouraging, Lhere are other transfusion -associated non -A.non-B agents which have not yet been identified.
The authors presented a Canadian perspective of the prevalence of antibodies to HCV (anti-HCV) in different risk groups.This is an updated version of a publication in tl1e Canada Diseases Weekly Report (8).whjch includes additional data from 85 hemodialysis patients and 260 individuals with no markers of recent hepatitis A orB virus infection.It also includes results of the recombinant immunoblot assay (RI BA) HCV test.

MATERIALS AND METHODS
An enzyme immunoassay test is now commercially available (Ortho Diagnostic Systems Inc) for the detection of anti-HCV.The validity of the test based on HCV protein cloned in yeast cells was estab lished by examining well documented test panels of sera from botl1 patients with non-A.non-Bpost transfusion hepatitis and implicated blood donors (9) .
Serum specimens from hemophiliacs.intravenous drug abusers.female prisoners.h omosexuals.hemodialysis patients in 1980-82.hemodialysis patients in 1990.suspected hepatitis patien ts (negative for markers of recent h epatitis A or B virus infection).and norm a l individuals were tested fo r anti-HCV.Sera from federal public servants were tested as normal controls.Th ese sera were obtained from the Med ical Services Clinic in Ottawa where p ublic servants a re given their ro u tine annual medical exam inations .Th e sources of samples tested a re given in Table 1.A large n um ber of fe m ale prisoners h ad a h istory of intravenou s dr ug abu se bu t the a u thors were u n able to obtain an accu rate number.No ne of the patien ts witho u t h epatitis A or B viru s infection h ad b een recen tly transfu sed .Th e sera from hemophiliacs.intravenous d rug abusers .female prisoners and homosexuals were kindly provided by Dr M O'Shaughnessy of the Federal Centre fo r AIDS.The sera from the hemodialysis patients taken du ring 1980-82 and 1990 were provided by Dr G Posen of tl1e Ottawa Civic Hospital.
Samples were tested by enzyme imm unoassay and those positive were repeat tested.The recom mended protocol was followed for setting up th e test.Th e enzyme immunoassay repeat positive samples were further tested by the RJBA HCV supplementary test (Ch iron Corp. Cali fornia) for confi rmation.Th e RI BA HCV test is an immunoblot test in which protein a n tigen s Cl00 -3 and 5-l-1 are immobilized as individu al bands on n itrocell u lose strips along with two levels of positive controls and a band for hum an superoxide dism utase.The kit protocol for performing the test was followed.

RESULTS
The resu lts showed that 68 .8% of tl1e hemophiliacs were positive for anti -HCV by enzyme in1111unoassay but only 53.7% were confirm ed by RJBA HCV (Table l).Th is showed a high p revalence of anti-HCV in Canadian hemophiliac patients.The prevalence was also h igh (54.2%) among the hemodialysis patients (1980-82).and test results by enzyme immunoassay and RIBA HCV we re U1e san1e.Only 14.1 % of hemodialysis patients we re positive fo r anti-HCV by RJBA HCV du ring 1990.Canadian intravenous drug abusers and femal e p 1 isoners had a p revalence rate of 42 .8%and 29.8%.respectively .by RIBA I-ICY .The prevalence by enzyme immunoassay was slightly higher.The prevalence rat e

DISCUSSION
The results showed a high prevalence (53.7%) of anti-HCV in Canadian hemophiliac patients.similar to findings previously reported from Germany and Spain (10 , 11).It was also observed that only 78% of samples positive by enzyme immunoassay were con firmed by RIBA HCV.Among the hemodialysis patients (1980 -82).a high prevalence of anti-HCV was detected by both enzyme immunoassay and RIBA HCV.This group had experienced many cases of non -A, non-B hepatitis .diagnosed by exclusion between 1980 and 1982.This explains the reason for a prevalence rate in this group higher than rates reported from other centres (10,11).In Germany and Spain (10,11).5.5% and 20% of hemodialysis patients.respectively.were positive for anti-HCV.whereas in Japan 18.7% were reported (12) to be positive for anti-HCV by enzyme immunoassay.On the other hand.only 14.1% of hemodialysis patients were positive for anti-HCV by RIBA HCV in 1990, similar to rates reported from other centres .This difference could be explained by the fact that non -A.non -B activity was low during 1990.Canadian intravenous drug abusers and female prisoners had a high prevalence of anti-HCV by RIBA HCV.Although the numbers were small.these rates may be indications of cases in general .The prevalence of anti-HCV in intravenous drug abusers in Canada was similar to those reported from Austria (50%) (13).The present authors are the first to report a high prevalence of anti-HCV in female prisoners.Indications are th•at the female prisoners were intravenous drug abusers before incarceration.
The prevalence rate for anti-HCV was low (2.3%) in homosexuals.similar to rates reported from Denmark (4.1%) (14).although a somewhat higher prevalence rate (8%) was reported from Spain (11).Four and onehalf per cent of the sera tested from individuals with no markers of recent hepatitis A or B virus infection were positive for anti-HCV by RIBA HCV.Also in this group, only 33.3% of enzyme immunoassay positive samples were confirmed by RIBA HCV.This shows the weakness of enzyme immunoassay for testing samples from low risk groups.In contrast, in a random serum set from normal individuals (federal public servants).only 1.2% of sera tested were positive for anti-HCV by RIBA HCV.In the Canadian blood donor population only 0.39% were positive for anti-HCV by enzyme immunoassay (personal communication).
These results show that HCV is an in1portant cause Anti-HCV in risk groups in Canada of hepatitis; particularly high rates were found among hemophiliacs.intravenous drug a busers, female prisoners and hemodialysis patients.indicating the in1portance of parenteral transmission.On the other h a nd, a lower prevalence rate (2.3%) an1ong homosexuals indicated that HCV is not readily transmitted by the sexual route , although occasional infection may occur.All results were confirmed by an immunoblot test (RIBA HCV) with the finding that in low risk groups a supplementary test is essential.
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Number Number anti -HCV repeat Number anti-HCV posi-
HCV was low (2.3%) in homosexuals by RIBA HCV.Among individuals with no markers of recent hepatitis A or B virus infections.the prevalence of anti-HCV was 13.4% by enzyme immunoassay and 4.5% by RIBA HCV.Sera from normal individuals (federal public servants) showed a low prevalence of anti-HCV by both enzyme immunoassay (2.0%) and RIBA HCV (1 .2%).
'Sera from individuals with no markers of recent hepatitis A virus (HA V) or hepatitis 8 virus (HBV) infections.EIA Enzyme immunoassay for anti-