Hepatitis B antigenemia among blood donors: the changing scene B. P. L. Moore, md,
frcp[c]; R. A. Perrault, md, ph d
Summary: For the period May 1973 to August 1974 inclusive, the mean prevalence of hepatitis B antigenemia (HB8Ag) in all Canadian provinces (per 100000 population) was, for "first-time" donors, 242 and, for "repeat" donors, 77. A modification of counterimmunoelectrophoresis was used in all 16 regional transfusion centres. The findings confirm the previously noted high prevalence for the Province of Quebec and the continuing relatively high prevalence for Canada. The prevalence of HB.Ag among donors could be lessened by institution of the following measures: development of a more effective technique for the screening of hepatitis carriers, study of nonparenterally transmitted hepatitis, better reporting of post-transfusion hepatitis, and greater discrimtnation in prescribing blood and blood components. Resume: La pr6sence de I'antigene de I'hepatite B dans le sSrum des donneurs de sang: le tableau canadien
changeant Durant la periode allant de mai 1973 a aout 1974 inclusivement, la prevalence moyenne de I'antigenemie
de
I'hepatite B (HBsAg) a ete, dans I'ensemble des provinces canadiennes, de 242 (sur 100 000 de la population) pour les "premiers" donneurs et de 77 pour les donneurs qui ont "renouvele" leur don. Dans les 16 centres regionaux de transfusion on a utilise une
immunoelectrophorese modifiee. Les constatations I'enquSte confirment la forte prevalence deja notee
contre
de dans la province de Quebec et la prevalence relative forte et continue dans I'ensemble du pays. II est possible de reduire la prevalence du HB8Ag parmi les donneurs en adoptant les mesures suivantes: mise au point d'une technique plus efficace pour le depistage des porteurs de I'hepatite, 6tude plus poussee de la transmission de I'hepatite par des voies nonparenterales, rapports sur la transmission de I'hepatite par des voies parenterales, et plus grande circonspection dans la prescription de sang et des elements du sang.
transfusion hepatitis. This report presents data demonstrating the changes in prevalence of HB8 antigenemia in the blood donor population during the last 3 years. In particular, the prevalence was determined among both "first-time" and "repeat" donors for the period May 1973 to August 1974 inclusive.
Method A modification of counterimmunoelectrophoresis (CIEP) with standardized reagents was used in all 16 regional trans¬ fusion centres.1 The proficiency of these centres with CIEP compared favourably with that of 24 other laboratories in different parts of the world.2 Results
Studies of the prevalence during 1973 of HBsAg among "first-time" blood donors and among "repeat" blood donors (i.e. those who had donated blood previously at some time)3 show that among "first-time" donors it was about the same as it had been in the overall donor population when screen¬ ing began,4 but that among "repeat" donors, who formed approximately 75% of the blood donor population, the pre¬ valence of HBsAg was lower, in varying degree across the
country. However, because the sampling of "first-time" donors was relatively small, a further sampling was taken from May 1973 to August 1974. The results, compiled from
raw data that were sex or ethnic
on the basis of age, shown in Table I. The mean
not standardized
background,
are
Table I.Prevalence of HBsAg among "first-time" and "repeat" volunteer blood donors, May 1973 to August 1974
Since the beginning of 1972 all blood donations collected by the Canadian Red Cross blood transfusion service have been screened for the presence of hepatitis B surface antigen (HBsAg) in the hope of decreasing the incidence of postFrom the Canadian Red Cross blood transfusion service, Toronto Reprint requests to: Dr. B. P. L. Moore, Director, Canadian Red Cross blood transfusion service, 95 Wellesley St. E., Toronto, Ont. M4Y 1H6
CMA JOURNAL/JANUARY 11, 1975/VOL. 112 53
prevalence (per 100 000 population) of HB5Ag among "first-time" donors was 242 (187 if data from the Province of Qu.bec are excluded), compared with 77 for "repeat" donors (29 if data from Quebec are omitted). It was not possible to establish the rate of new infections among "repeat" donors from these data for reasons to be discussed. Among persons who donated blood more than once, the prevalence of HB5Ag decreased by an average of 84% in all provinces except Quebec, in which the high prevalence of HB5Ag among blood donors has previously been noted.4'5 The high carrier rate among "repeat" donors in Quebec and the persistence of HB.Ag among "repeat" donors in other provinces may have several explanations: some donors last donated blood before HB.Ag screening began; others became carriers since their 'last donation; yet others, for technical reasons, had been wrongly classed as CIEPnegative at the time of their last donation; and a few GIEP-positive donors did not heed warnings to stop donating blood (though, with respect to the last group, electronic data-processing of donor records will soon facilitate detection of these donors at 'blood clinics). Discussion Clearly, there is a reservoir of hepatitis B antigenemia among healthy adults, which results in a continued and relatively high prevalence of HB.Ag among the newcomers to the blood donor pool. Although there has 'been an appreciable decrease in the 'H'B5Ag carrier rate among those who have donated blood previously (with the exception of Qu6bec donors), donors with HB5 antigenemia are still being detected. Recent studies suggest that HB5Ag may be transmitted 'by saliva and by sweat and by sexual intercourse.6 This may contribute to the maintenance of a persistent, relatively high prevalence of hepatitis B antigenensia in the general population. It is therefore possible that the reservoir of hepatitis B antigenemia may not diminish significantly until more effective methods have been developed to control transmission. CIEP is known to have failings: it is not the most sensitive technique available and its successful use depends largely upon the operator's skill and visual acuity.2 Improved test reproducibility and increased sensitivity without loss of specificity, combined with an objective method for reading results, are needed if detection is to become more accurate. We are advised* that the latest radioimmunoassay procedures, although expensive and more time-consuming, provide such technical advantages. *We acknowledge the assistance of an ad hoc advisory committee cornposed (in alphabetical order) of Dr. F. R. Bishai, Mr. R. Y. Dodd and Drs. J. Duravetz, 5. V. Feinham, R. M. Guevin, L. P. Spence and P. E. Taylor
54 CMA JOURNAL/JANUARY 11, 1975/VOL. 112
Our main concern is to make blood replacement therapy safer by diminishing the frequency of post-transfusion hepatitis. A screening program for HB.Ag is but one way of tackling this problem. Other approaches that should not be ignored include the following: (a) development of a test to detect hepatitis type A infection; (b) determination of whether agents other than those of hepatitis type A and type B are involved in the transmission of post-transfusion hepatitis; (c) development of more sensitive techniques for the detection of 'hepatitis B carriers; (d) study of nonparenteral spread of hepatitis B infection; and (e) greater discrimination in the prescription of blood and blood components, with greater emphasis on the use of erythrocytes reconstituted from the frozen state and on autologous transfusions. The effectiveness of our screening program for HB5Ag in blood donors is difficult to assess because, although viral hepatitis is a notifiable disease, the reporting of post-transfusion hepatitis (PTH) leaves much to be desired. Hepatitis B infection may have an incubation period of up to 180 days; thus, it is easy to miss the connection between an earlier transfusion and the present infection. We therefore ask every physician to report to his or her nearest regional transfusion centre any patient with suspected viral hepatitis with a history of having received a transfusion of blood or blood products in the previous 6 months. This step would be additional to the obligation to report all cases of viral hepatitis to the local medical officer of health. Accurate reporting of all suspect cases of PTH will make it possible subsequently to trace the implicated blood donors and have them retested by the national hepatitis reference centre of the laboratory centre for disease control, Health and Welfare Canada, Ottawa. The identification of HB8Ag carriers among these donors will enable us further to lessen the likelihood of HB.Ag carriers being present in the repeat" donor pool. Greater awareness and reporting of PTH among physicians will thus materially contribute to safer transfusion. We thank Dr. Patricia E. Taylor for her many helpful comments during the preparation of this manuscript. References 1. MOORE BPL, MEADE D: Counter-immunoelectrophoresis for detection of hepatitis B antigen and antibody: a technique for large scale use. Can .1 Public Health 63: 453, 1972 2. MOORE BPL, MEADE D, TAYLOR PE, et al: An international proficiency survey for the detection of hepatitis B antigen and antibody in blood donations by counter-immunoelectrophoresis. Vox Sang 26: 128, 1974 3. MOORE BPL: Prevalence of HR Ag and HR Ab in the Canadian blood-donor population. Haematologia 1974 (in press) 4. Idem: Incidence of hepatitis B antigen and antibody among Canadian volunteer blood donors (correspondence). Can Med Assoc 1 107: 396, 1972 5. Idem: The incidence of hepatitis-associated (Australia) antigen among Canadian volunteer blood donors. Can I Public Health 63: 104, 1972 6. TELATAR H, KAYHAN B, Kas 5, et al: HR Ag in sweat. Lancet II: 461, 1974
frcp[c]; R. A. Perrault, md, ph d
Summary: For the period May 1973 to August 1974 inclusive, the mean prevalence of hepatitis B antigenemia (HB8Ag) in all Canadian provinces (per 100000 population) was, for "first-time" donors, 242 and, for "repeat" donors, 77. A modification of counterimmunoelectrophoresis was used in all 16 regional transfusion centres. The findings confirm the previously noted high prevalence for the Province of Quebec and the continuing relatively high prevalence for Canada. The prevalence of HB.Ag among donors could be lessened by institution of the following measures: development of a more effective technique for the screening of hepatitis carriers, study of nonparenterally transmitted hepatitis, better reporting of post-transfusion hepatitis, and greater discrimtnation in prescribing blood and blood components. Resume: La pr6sence de I'antigene de I'hepatite B dans le sSrum des donneurs de sang: le tableau canadien
changeant Durant la periode allant de mai 1973 a aout 1974 inclusivement, la prevalence moyenne de I'antigenemie
de
I'hepatite B (HBsAg) a ete, dans I'ensemble des provinces canadiennes, de 242 (sur 100 000 de la population) pour les "premiers" donneurs et de 77 pour les donneurs qui ont "renouvele" leur don. Dans les 16 centres regionaux de transfusion on a utilise une
immunoelectrophorese modifiee. Les constatations I'enquSte confirment la forte prevalence deja notee
contre
de dans la province de Quebec et la prevalence relative forte et continue dans I'ensemble du pays. II est possible de reduire la prevalence du HB8Ag parmi les donneurs en adoptant les mesures suivantes: mise au point d'une technique plus efficace pour le depistage des porteurs de I'hepatite, 6tude plus poussee de la transmission de I'hepatite par des voies nonparenterales, rapports sur la transmission de I'hepatite par des voies parenterales, et plus grande circonspection dans la prescription de sang et des elements du sang.
transfusion hepatitis. This report presents data demonstrating the changes in prevalence of HB8 antigenemia in the blood donor population during the last 3 years. In particular, the prevalence was determined among both "first-time" and "repeat" donors for the period May 1973 to August 1974 inclusive.
Method A modification of counterimmunoelectrophoresis (CIEP) with standardized reagents was used in all 16 regional trans¬ fusion centres.1 The proficiency of these centres with CIEP compared favourably with that of 24 other laboratories in different parts of the world.2 Results
Studies of the prevalence during 1973 of HBsAg among "first-time" blood donors and among "repeat" blood donors (i.e. those who had donated blood previously at some time)3 show that among "first-time" donors it was about the same as it had been in the overall donor population when screen¬ ing began,4 but that among "repeat" donors, who formed approximately 75% of the blood donor population, the pre¬ valence of HBsAg was lower, in varying degree across the
country. However, because the sampling of "first-time" donors was relatively small, a further sampling was taken from May 1973 to August 1974. The results, compiled from
raw data that were sex or ethnic
on the basis of age, shown in Table I. The mean
not standardized
background,
are
Table I.Prevalence of HBsAg among "first-time" and "repeat" volunteer blood donors, May 1973 to August 1974
Since the beginning of 1972 all blood donations collected by the Canadian Red Cross blood transfusion service have been screened for the presence of hepatitis B surface antigen (HBsAg) in the hope of decreasing the incidence of postFrom the Canadian Red Cross blood transfusion service, Toronto Reprint requests to: Dr. B. P. L. Moore, Director, Canadian Red Cross blood transfusion service, 95 Wellesley St. E., Toronto, Ont. M4Y 1H6
CMA JOURNAL/JANUARY 11, 1975/VOL. 112 53
prevalence (per 100 000 population) of HB5Ag among "first-time" donors was 242 (187 if data from the Province of Qu.bec are excluded), compared with 77 for "repeat" donors (29 if data from Quebec are omitted). It was not possible to establish the rate of new infections among "repeat" donors from these data for reasons to be discussed. Among persons who donated blood more than once, the prevalence of HB5Ag decreased by an average of 84% in all provinces except Quebec, in which the high prevalence of HB5Ag among blood donors has previously been noted.4'5 The high carrier rate among "repeat" donors in Quebec and the persistence of HB.Ag among "repeat" donors in other provinces may have several explanations: some donors last donated blood before HB.Ag screening began; others became carriers since their 'last donation; yet others, for technical reasons, had been wrongly classed as CIEPnegative at the time of their last donation; and a few GIEP-positive donors did not heed warnings to stop donating blood (though, with respect to the last group, electronic data-processing of donor records will soon facilitate detection of these donors at 'blood clinics). Discussion Clearly, there is a reservoir of hepatitis B antigenemia among healthy adults, which results in a continued and relatively high prevalence of HB.Ag among the newcomers to the blood donor pool. Although there has 'been an appreciable decrease in the 'H'B5Ag carrier rate among those who have donated blood previously (with the exception of Qu6bec donors), donors with HB5 antigenemia are still being detected. Recent studies suggest that HB5Ag may be transmitted 'by saliva and by sweat and by sexual intercourse.6 This may contribute to the maintenance of a persistent, relatively high prevalence of hepatitis B antigenensia in the general population. It is therefore possible that the reservoir of hepatitis B antigenemia may not diminish significantly until more effective methods have been developed to control transmission. CIEP is known to have failings: it is not the most sensitive technique available and its successful use depends largely upon the operator's skill and visual acuity.2 Improved test reproducibility and increased sensitivity without loss of specificity, combined with an objective method for reading results, are needed if detection is to become more accurate. We are advised* that the latest radioimmunoassay procedures, although expensive and more time-consuming, provide such technical advantages. *We acknowledge the assistance of an ad hoc advisory committee cornposed (in alphabetical order) of Dr. F. R. Bishai, Mr. R. Y. Dodd and Drs. J. Duravetz, 5. V. Feinham, R. M. Guevin, L. P. Spence and P. E. Taylor
54 CMA JOURNAL/JANUARY 11, 1975/VOL. 112
Our main concern is to make blood replacement therapy safer by diminishing the frequency of post-transfusion hepatitis. A screening program for HB.Ag is but one way of tackling this problem. Other approaches that should not be ignored include the following: (a) development of a test to detect hepatitis type A infection; (b) determination of whether agents other than those of hepatitis type A and type B are involved in the transmission of post-transfusion hepatitis; (c) development of more sensitive techniques for the detection of 'hepatitis B carriers; (d) study of nonparenteral spread of hepatitis B infection; and (e) greater discrimination in the prescription of blood and blood components, with greater emphasis on the use of erythrocytes reconstituted from the frozen state and on autologous transfusions. The effectiveness of our screening program for HB5Ag in blood donors is difficult to assess because, although viral hepatitis is a notifiable disease, the reporting of post-transfusion hepatitis (PTH) leaves much to be desired. Hepatitis B infection may have an incubation period of up to 180 days; thus, it is easy to miss the connection between an earlier transfusion and the present infection. We therefore ask every physician to report to his or her nearest regional transfusion centre any patient with suspected viral hepatitis with a history of having received a transfusion of blood or blood products in the previous 6 months. This step would be additional to the obligation to report all cases of viral hepatitis to the local medical officer of health. Accurate reporting of all suspect cases of PTH will make it possible subsequently to trace the implicated blood donors and have them retested by the national hepatitis reference centre of the laboratory centre for disease control, Health and Welfare Canada, Ottawa. The identification of HB8Ag carriers among these donors will enable us further to lessen the likelihood of HB.Ag carriers being present in the repeat" donor pool. Greater awareness and reporting of PTH among physicians will thus materially contribute to safer transfusion. We thank Dr. Patricia E. Taylor for her many helpful comments during the preparation of this manuscript. References 1. MOORE BPL, MEADE D: Counter-immunoelectrophoresis for detection of hepatitis B antigen and antibody: a technique for large scale use. Can .1 Public Health 63: 453, 1972 2. MOORE BPL, MEADE D, TAYLOR PE, et al: An international proficiency survey for the detection of hepatitis B antigen and antibody in blood donations by counter-immunoelectrophoresis. Vox Sang 26: 128, 1974 3. MOORE BPL: Prevalence of HR Ag and HR Ab in the Canadian blood-donor population. Haematologia 1974 (in press) 4. Idem: Incidence of hepatitis B antigen and antibody among Canadian volunteer blood donors (correspondence). Can Med Assoc 1 107: 396, 1972 5. Idem: The incidence of hepatitis-associated (Australia) antigen among Canadian volunteer blood donors. Can I Public Health 63: 104, 1972 6. TELATAR H, KAYHAN B, Kas 5, et al: HR Ag in sweat. Lancet II: 461, 1974
