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Tony G Butler, Kate A Dolan, Mark J Ferson, Linda M McGuinness, Phillip R Brown and Peter W Robertson
MJA 1997; 166: 127
For comment see Crofts
Abstract - Introduction - Methods - Laboratory methods - Statistical methods - Results - Participants - Serology and risk factors - Discussion - Acknowledgements - References - Authors' details
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Abstract |
Objectives: To determine the prevalence of
hepatitis B virus (HBV) and hepatitis C virus (HCV) infection among
inmates entering the New South Wales correctional system and to
examine risk factors for infection. Design: Cross-sectional survey. Setting: Reception Centre at Long Bay Correctional Centre, Sydney, New South Wales, June to December 1994. Participants: 408 adult male inmates received at the reception centre (28% of the 1450 new inmates eligible for compulsory HIV testing). Outcome measures: Presence of HBV core and surface antibody and surface antigen; HCV antibody; risk factors; inmates' knowledge about risk factors. Results: 37% of inmates tested positive for HCV antibody, 31% for HBV core antibody and 3.2% for HBV surface antigen (indicating recent infection or carrier status). Among those who reported a history of injecting illegal drugs, rates rose to 66% for HCV antibody and 43% for HBV core antibody. Prevalence of HBV and HCV antibodies was similar in Aboriginal and non-Aboriginal inmates, but HBV antigen carrier rate was significantly higher among Aboriginals (12% versus 2.2%). Knowledge about hepatitis risk factors was poor (only 20% named injecting drug use), although recidivists were significantly better informed than those new to the correctional system. Multivariate analysis identified injecting drug use, past exposure to hepatitis B virus and previous imprisonments as significant predictors for HCV infection, and age over 25 years and HCV antibodies for HBV infection. Conclusions: Results suggest that about a third of adult male prisoners entering the NSW correctional system may have been infected with HBV or HCV. Measures such as education about hepatitis risk factors and HBV vaccination are needed to reduce hepatitis transmission in this population. MJA 1997; 166: 127-130 |
Introduction |
The reported high prevalence of hepatitis B and C in prison
populations is attributed to the disproportionate number of people
in prisons who engage in risk behaviours, particularly injecting
illegal drugs.1-8 It is
estimated that up to 60% of inmates are committed for drug-related
offences.9 Further, an
Australian study estimated that during their incarceration 25%-44%
of inmates occasionally injected illegal drugs, 14%-34% engaged in
occasional anal intercourse and 5%-18% did both.10
Among inmates entering the Victorian prison system in 1991 and 1992, 39% were positive for hepatitis C antibody (including 64% of those reporting a history of injecting illegal drugs), 33% were positive for hepatitis B antibody and 2.5% for hepatitis B surface antigen.11 There are no recent studies of the prevalence of infection with hepatitis B and C viruses (HBV and HCV) in New South Wales prisons. Our study aimed to determine the prevalence of HBV and HCV infection among inmates entering the NSW correctional system and to examine the risk factors associated with these infections. |
Methods |
The study was performed at the Reception Centre at Long Bay
Correctional Centre, Sydney, NSW, from June to December 1994. The
Reception Centre receives about 51% of adult males entering
the NSW correctional system, most of whom are then transferred to
other prisons.
At the time of our survey, all inmates entering NSW prisons were routinely screened for the human immunodeficiency virus (HIV) by public health nurses of the Corrections Health Service. Inmates were also invited to participate in the hepatitis survey. Recruitment depended on the nurses' availability to enrol inmates during HIV screening, and in busy periods it was not always possible to enrol all new inmates. No information was sought from those who did not agree to participate. Inmates who agreed to participate were briefed on the project and informed that a consent form had to be signed, a blood specimen was needed, and a risk factor questionnaire would be administered by the nurse. Nurses also asked inmates to describe ways in which hepatitis can be transmitted. All inmates who tested positive for HBV and HCV antibodies were counselled by public health nurses. HCV-positive inmates routinely receive follow-up liver function tests. Inmates who reported having had HBV vaccination were given booster vaccination if antibody tests indicated they were not immune. All other inmates who tested negative for HBV core antibody were offered hepatitis B vaccination. Ethics approval for the study was granted by the Eastern Sydney Area Health Service Ethics Committee and the NSW Department of Corrective Services. |
Laboratory methods |
HBV core antibody (indicating past exposure) was tested with an
anti-HBc enzyme immunoassay kit (General Biologicals, Taiwan).
Samples positive for HBV core antibody were tested for HBV surface
antigen (indicating carrier status) with the HBsAg-enzyme
immunoassay (Murex, Dartford); positive results were confirmed by
HBs reverse passive haemagglutination assay (Serodia, Tokyo).
Inmates who reported having been vaccinated against hepatitis B were tested for HBV surface antibody with the HBsAb-enzyme immunoassay (General Biologicals, Taiwan). A level of 30 IU/mL was considered the minimum necessary for immunity. HCV antibody was detected with the Innotest HCVAbIII assay (Innogenetics, Belgium). Reactive samples were retested in duplicate and, if again reactive, were tested with anti-HCV (Murex, Dartford). Samples that were reactive in each of the two types of assay were classified as positive, and those with discrepant results as equivocal. |
Statistical methods | Relative risks were calculated with the statistical software Epi Info-6,12 and logistic regression was performed with the software SPSS-6. 13 The c 2 test was used to test for association between Aboriginality and serostatus. |
Results | |
Participants |
About 1450 inmates were tested for HIV at the Long Bay Reception Centre
between June and December 1994. Of these, 410 adult males (28%)
consented to be screened for HBV and HCV antibodies. It is not known how
many of the remainder were not invited to participate and how many
refused. Two inmates were counted twice as they were released and
reincarcerated during the study period. Results of their second
tests were excluded from the analysis.
The 408 subjects were aged 17-73 years (mean, 30.6 years; standard deviation, 10.1), and 296 (73%) had been imprisoned previously. Country of origin was: Australia, 80%; Europe, 8.6%; New Zealand and the Pacific Islands, 3.5%; Asia, 2.7%; the Middle East, 2.7%; and elsewhere or unknown, 2.5%. Forty-one inmates (10%) identified themselves as Aboriginal. |
Serology and risk factors |
Prevalence of HBV and HCV antibodies and HBV antigens is shown in Box 1 (below).
About a third of inmates were positive for HBV core antibody (31%) or
for HCV antibody (37%), with 21% positive for both. Among those who
reported having received HBV vaccination, only 34% had HBV surface
antibody levels (indicating immunity).
 No significant differences were found between Aboriginal and non-Aboriginal inmates in prevalence of HBV core and HCV antibodies. However, the HBV carrier rate was significantly higher among Aboriginals (12% versus 2.2%; c2 =11.8; P < 0.001). Among those reporting hepatitis B vaccination, more Aboriginals (50%) than non-Aboriginals (32%) had developed immunity, but the difference was not significant. The association between risk behaviours and HBV and HCV infection is shown in Box 2. The risk of each infection was significantly increased by a history of injecting drug use, previous imprisonment, sharing of injecting equipment, age over 25 years, injecting drug use during previous imprisonment, and tattooing (P< 0.05 or less). Risk also increased significantly with increasing numbers of previous imprisonments (P< 0.01 or less). Risk of HCV infection was also significantly increased by tattooing, sex with an injecting drug user and presence of HBV antibodies (P< 0.001). Among the 67 inmates who reported injecting drug use during a previous imprisonment, 77% were positive for HCV antibody and 56% for HBV antibody. In addition, among the 150 inmates positive for HCV antibody, only 14 (9%) did not report a history of injecting drug use. The following independent variables were entered into a logistic regression model, with HBV and HCV infection as separate outcome variables: injecting drug use, sex with an injecting drug user, tattoos, Aboriginality, age group (over 25 years versus 25 years and under), previous imprisonment, and HBV or HCV infection. For HCV infection, significant predictors were injecting drug use (odds ratio [OR], 19.9; P< 0.001), presence of HBV antibody (OR, 5.6; P< 0.001), and previous imprisonment (OR, 3.9; P< 0.001). For HBV infection, significant predictors were presence of HCV antibody (OR, 6.2; P< 0.001), and age over 25 years (OR, 3.4; P< 0.001). Among the 85 inmates positive for both HBV and HCV antibodies, 83 (98%) reported previous imprisonment, 78 (92%) reported injecting drug use, 40 (47%) reported sharing injecting equipment, 64 (75%) had tattoos, and 31 (36%) reported being tattooed in prison. Inmates' knowledge of risk factors for hepatitis B and C transmission is shown in Box 3 (below). Few inmates were knowledgeable about risk factors, with injecting drug use nominated by only 20% and tattooing by only 2%. However, those who had been imprisoned previously were significantly more likely to identify injecting drug use as a risk factor than those new to the correctional system, and significantly less likely to answer "no idea" about risk factors. |
Discussion |
Our results agree with those of a 1991-1992 study of Victorian prison
inmates.11 We found that 37%
of inmates were positive for HCV antibodies (39% in Victoria), 31% for
HBV antibodies (33% in Victoria), and 3.2% for HBV surface antigen B
(2.5% in Victoria). Our results also agree with those of two Victorian
studies, which found rates of 62% and 68%, respectively, for HCV
infection among injecting drug users.8,14
Extrapolating our results to the current NSW male prison population of over 6000 implies that almost 2000 inmates are likely to have been exposed to HBV, about 200 are HBV carriers, and over 2000 are HCV-antibody-positive. In contrast, there were 25 HIV-positive inmates in NSW correctional centres at the time of the study (0.4%; 23 male and 2 female) (unpublished data). NSW prison inmates are offered hepatitis B vaccination if their sentences exceed six months and they are considered "at risk". However, inmates with shorter sentences may also be at risk. We believe that all inmates have the right to be protected from possible infection and that all should start a course of hepatitis B vaccination on entry to the correctional system. It may be appropriate to use recently described accelerated vaccination schedules, which provide protective levels of anti-hepatitis B surface antibody relatively quickly.15 In addition, if hepatitis B vaccination courses are not completed in prison, inmates should be educated about the need to complete them after release. We found that among the 108 inmates (26%) who reported having had hepatitis B vaccination only a third were immune, possibly because of failure to complete the recommended vaccination schedule. Vaccination history could not be verified. We found that previous imprisonment was a significant risk factor for HCV infection, suggesting that measures to minimise the spread of hepatitis within prisons are essential. In addition, as many injecting drug users spend time in prison, it is an appropriate point for intervention to break the cycle of infection by educating them about risks for hepatitis transmission and providing vaccination. Prison education programs seem to have improved awareness about transmission of hepatitis, as inmates with a prison history were more likely to know the role of injecting drug use and less likely to have "no idea" about hepatitis transmission. However, knowledge was still poor, and only 2% of inmates identified tattooing as a risk factor for hepatitis transmission, which is of concern given the popularity of tattooing in this population. The link between tattooing and HCV infection has been identified elsewhere,16,17 and should receive more emphasis in hepatitis education programs. The recent decision by the NSW Department of Corrective Services to make condoms available in prisons may reduce hepatitis transmission. Other measures, such as removing obstacles for accessing bleach, and needle exchange, should also be considered in the fight to curb the spread of hepatitis. Our findings suggest that chronic hepatitis may become one of the prison system's major health concerns over the next two decades. |
Acknowledgements | The study was funded in part by a grant from the NSW Health Department AIDS/Infectious Diseases Branch. We wish to thank the nursing staff at the NSW Corrections Health Service for assistance in data collection (Amanda Christensen, Sheryl Frewin, Marion Grey, Cherylyn Jesson, Linda Kemp, Jodie Lee, and Sandra Parsons). |
References |
(Received 10 Jan, accepted 21 Oct, 1996) |
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