The sentinel surveillance study of hepatitis testing, which began in 2002, aims to supplement routine surveillance of hepatitis A, B and C infections in England by providing information on trends in testing, individual risk exposures and clinical symptoms.
The study collects information on hepatitis A, B and C testing carried out in participating centres regardless of test result and therefore can also be used to estimate prevalence in those individuals tested.
This report includes, for the first time:
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Data on hepatitis A-specific IgM testing
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Data on hepatitis B surface antigen (HBsAg) testing are included for the first time this quarter: these are shown in sections 2a (antenatal testing) and 2b (non-antenatal testing).
In addition, the following changes to the content and presentation of this report should be noted:
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Region is now based on the Strategic Health Authority (SHA) of the test request location, in contrast to previous reports, in which region was assigned based on the location of the sentinel centre;
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In contrast to previous reports, individuals less than one year of age at first test are excluded from all data on anti-HCV testing. Please note, however, that such individuals are included in data on HBsAg testing.
Work is underway on the classification of individuals with evolving hepatitis B infections: these data will be presented in future reports.
HEPATITIS C
During the last quarter of 2007, a total of 32,761 individuals were tested at least once for hepatitis C-specific antibodies (anti-HCV) in 19 participating sentinel centres (Table 6). This is the first time these individuals had been reported to the sentinel surveillance scheme.
Overall, 4.3% of individuals tested for anti-HCV were positive, though this varied by region (table 6). The high proportion of positives observed among individuals tested in the North East is likely to be due to changes in sample referral patterns: many hospitals in this area have started carrying out their own hepatitis testing rather than sending samples to the sentinel laboratory. The services to which the sentinel laboratory continues to provide testing include those accessed by individuals at high risk of hepatitis C infection, which may explain the high percentage positive seen here. For example, 59 of the 264 individuals tested at the laboratory during this quarter were tested in prison health services, 21 of whom were positive.
It is important to note that no laboratory methods are currently available to distinguish between acute, chronic or resolved hepatitis C virus infections. Positive anti-HCV results do not therefore necessarily represent incident infections and the data presented here should be interpreted with care.
Table 6. Number of individuals tested, and testing positive, for anti-HCV in participating centres, October – December 2007
| Region (number of centres) | Number tested | Number positive (%) |
| East Midlands (1) | 3,274 | 76 (2.3) |
| East of England (1) | 1,258 | 53 (4.2) |
| London (5) | 8,435 | 341 (4.0) |
| North East (1) | 264 | 25 (9.5) |
| North West (5) | 7,287 | 385 (5.3) |
| South Central (1) | 888 | 38 (4.3) |
| South East Coast (1) | 2,771 | 40 (1.4) |
| South West (1) | 3,633 | 244 (6.7) |
| Wales* | 15 | 0 (0.0) |
| West Midlands (1) | 1,360 | 51 (3.8) |
| Yorkshire and Humberside (2) | 3,576 | 151 (4.2) |
| Total, all regions (19) | 32,761 | 1,404 (4.3) |
* Although all sentinel centres are in England , a small amount of first-line testing from general practices in Wales is carried out by laboratories in the North West and West Midlands.
Excludes reference and confirmatory testing. Excludes individuals aged less than one year, in whom positive tests may reflect the presence of passively-acquired maternal antibody rather than true infection. Some duplication of individual patients may occur due to limitations of the information supplied. All data are provisional.
Of the 1,404 individuals testing positive for anti-HCV during the last quarter of 2007, 649 (46.2%) were also tested for HCV RNA by PCR. Of these individuals, 431 were PCR positive (66.4%).
Sex was reported for the majority of people tested. As in previous quarters, similar numbers of males and females were tested (table 7); the ratio of males to females tested was 1.0:1. The ratio of males to females testing positive was 2.1:1. The majority (64.9%) of people tested were aged 15-44 years. Excluding individuals for whom age is unknown, the percentage of individuals overall testing positive was highest among people aged 35-54 years. However, this varied slightly by sex, with the highest prevalence in women observed among those aged between 25-44 years but in men among those aged between 35-55 years.
Table 7. Age and sex of individuals tested for anti-HCV in participating centres, October – December 2007
| Age group | Female | Male | Unknown | Total |
| Number tested | Number positive (%) | Number tested | Number positive (%) | Number tested | Number positive (%) | Number tested | Number positive (%) |
| 1-14 | 223 | 2 (0.9) | 237 | 3(1.3) | 5 | 0 (0.0) | 465 | 5 (1.1) |
| 15-24 | 3,602 | 40 (1.1) | 2,506 | 40 (1.6) | 119 | 0 (0.0) | 6,227 | 80 (1.3) |
| 25-34 | 3,822 | 153 (4.0) | 3,972 | 227 (5.7) | 250 | 5 (2.0) | 8,044 | 385 (4.8) |
| 35-44 | 2,887 | 119 (4.1) | 3,879 | 346 (8.9) | 215 | 11 (5.1) | 6,981 | 476 (6.8) |
| 45-54 | 1,825 | 70 (3.8) | 2,163 | 196 (9.1) | 108 | 5 (4.6) | 4,096 | 271 (6.6) |
| 55-64 | 1,422 | 42 (3.0) | 1,562 | 86 (5.5) | 49 | 3 (6.1) | 3,033 | 131 (4.3) |
| ≥65 | 1,763 | 19 (1.1) | 1,942 | 28 (1.4) | 52 | 0 (0.0) | 3,757 | 47 (1.3) |
| Unknown | 34 | 1 (2.9) | 47 | 4 (8.5) | 77 | 4 (5.2) | 158 | 9 (5.7) |
| Total, all age groups | 15,578 | 446 (2.9) | 16,308 | 930 (5.7) | 875 | 28 (3.2) | 32,761 | 1,404 (4.3) |
Excludes reference and confirmatory testing. Individuals aged less than one year are excluded since positive tests in this age group may reflect the presence of passively-acquired maternal antibody rather than true infection. Some duplication of individual patients may occur due to limitations of the information supplied. All data are provisional.
To provide an indication of trends in testing, data from the 19 sentinel centres from which full data were available were compared for the final quarters of 2006 and 2007. In the period October to December 2007, 1,404 of 32,761 (4.3%) people tested were positive for anti-HCV, compared to 1,622 of 29,766 (5.4%) for the same period in 2006. This suggests increased testing of people at lower risk of infection.
It should be noted that these data relate to different sentinel centres to those for whom trends data were presented in the last quarterly report and therefore comparisons should not be made between reports. However, figure 2 shows the five-weekly moving average for number of people tested for anti-HCV and percentage positive over the last year (January 2007 to December 2007) for the 19 centres from which full data were available.
Apart from troughs during the Christmas and New Year holiday period, levels of anti-HCV testing appear to remain fairly steady over the course of the year. Interestingly, the three peaks in testing in the second half of the year correspond to simultaneous troughs in the percentage positive, perhaps suggesting increased testing of people at low risk of infection.
Figure 2. Five-weekly moving average of number of people tested, and percentage positive, for anti-HCV between January 2007 and December 2007. (Note difference in scales to Figure 1.)
References 1 Health Protection Agency. Health Protection Report [serial online] 2006; 1 (33 ): Immunisation. Available at: http://www.hpa.org.uk/hpr/archives/2007/hpr3407.pdf
