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INFECTIOUS DISEASE SURVEILLANCE
in Canadian Federal Penitentiaries 2005-2006

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Part II: Results

Chapter 4: Hepatitis A (HAV) and Hepatitis B (HBV)

Aggregate IDSS HAV / HBV Data

The IDSS captures case reports of HAV and HBV but does not include testing, treatment or vaccination information. HAV case reporting via the aggregate IDSS system commenced in 2005. Table 4.1 shows the overall results for both HAV and HBV case reports for 2000 to 2006. There were no HAV cases reported in 2005 and only one acute HAV case was reported in 2006. From a high of 43 cases diagnosed in 2001, there were 6 HBV cases reported in 2005 and 9 in 2006. The overall reported incidence rate for acute HBV was 0.05% in 2005 and 0.07% in 2006.

Table C.1, Appendix C shows the acute HAV and acute HBV cases reported by region and gender. Regional variation is observed in the prevalence of reported HBV cases as the Quebec Region accounted for 4 of 6 (66%) cases in 2005 and 5 of 9 (56%) cases in 2006.

HAV / HBV Immunization Data

The number of immunizations for HAV and HBV were not collected in either the IDSS or the Web-IDSS for 2005 and 2006; however, since vaccines are paid for from a national fund, purchase orders for fiscal year 2004-2005 were reviewed to determine the number of vaccine units ordered per region. Dividing the number of units ordered by the standard dosage regimen (i.e., a standard course of Vaqta® is 2 doses) an estimate of the immunization coverage can be made (Figure 4.1). However this does not account for spoilage, wasteage, vaccine unused, or partial or incomplete doses in a given fiscal year. Unfortunately due to a change in invoicing patterns, data on vaccine purchases for subsequent fiscal years were not available.

Figure 4.1 indicates that 989 inmates could have received vaccination with Vaqta®, 965 with Engerix®, and 1,821 with Twinrix®. Combined, this means that 2,810 inmates could have been vaccinated against HAV and 2,786 against HBV.

Enhanced Surveillance: Web-IDSS HAV / HBV Data Results

The enhanced Web-IDSS surveillance system captures more detailed information on HAV and HBV than the IDSS which only captures case reports. On admission, inmates are asked about previous HAV and HBV testing, the results, and vaccination history for both HAV and HBV. Inmates are offered serological screening for evidence of immunity, either through natural infection or vaccination, to both hepatitis A and B. Rarely are self-reports of previous immunizations taken on face value, since vaccination cards or histories do not generally accompany inmates on admission; rather, a blood sample9 is drawn for serology testing to confirm the report10. Those without evidence of immunity are offered immunization.

Appendix C contains more detailed results for HAV and HBV testing and vaccination history reported as new admission or general population inmate at CSC. These results are presented by region and gender (Tables C.2.i, C.2.ii, C.3.i, C.3.ii) and by origin (Tables C.2.iii, C.2.iv, C.3.iii, C.3.iv).

Appendix C, Table C.4.i and C.4.ii show the HAV and HBV serology results interpreted as “infectious” stratified by inmate type (new admission and general population), gender and region (Table C.4.i) and origin (Table C.4.ii). For HAV, this includes all serology reports reactive for anti-HAV IgM. For HBV, all serology reports reactive for anti-HBc IgM are classified as acute HBV active cases. Serology reports reactive for anti-HBc IgM and/or HBsAg are classified as HBV carriers. An overall summary of Web-IDSS data for HAV and HBV is presented in Table 4.2.

Hepatitis A Virus (HAV)

New Admissions
History of HAV Testing and Vaccination

Among new admissions in 2005-2006, 1,892 (32.4%) reported a previous serology test for HAV; reported previous test was higher among females (39.6%) compared to males (32.0%) (see Appendix C, Table C.2.i, C.2.iii and Table 4.2). Among males, the highest rate was seen in Ontario (37.7%) and lowest in Quebec (20.7%). Among females, the highest rate was seen in Pacific (52.9%) and the lowest in Atlantic (19.6%) (Appendix C, Table C.2.i). A higher proportion of new admissions of Canadian-born Aboriginal origin reported a previous HAV test (39.0%) compared to Canadian-born non-Aboriginal (30.7%) or Foreign-born (24.8%) (Appendix C, Table C.2.iii). Overall, 3.6% of new admissions reported that they tested positive on a previous HAV test and 11.8% of these individuals report that they received “treatment” for HAV11.

Among new admissions in 2005-2006, 1,359 (23.3%) reported a previous HAV vaccination (see Appendix C, Table C.2.i, C.2.iii and Table 4.2). Reported previous vaccination was higher among females (28.9%) compared to males (23.0%). Among males, the highest rate was seen in Quebec (47.7%) and lowest in Ontario (8.2%). Among females, the highest rate was seen in Pacific (47.1%) and the lowest in Atlantic (13.7%) (Appendix C, Table C.2.i). A higher proportion of new admissions of Canadian-born Aboriginal origin reported previous HAV vaccination (27.7%) compared to Canadian-born non-Aboriginal (23.3%) or Foreign-born (11.6%) (Appendix C, Table C.2.iii).

 

Table 4.1: Number of Hepatitis A and Hepatitis B Cases, Inmates, 2000 - 2006
  2000 2001 2002 2003 2004 2005 2006

Source: IDSS Aggregate Surveillance Data, CSC 2010

Total Number of HAV Cases 0 1
Acute HAV Prevalence Rate 0.00% 0.01%
Total Number of HBV Cases 13 43 30 17 16 6 9
Acute HBV Prevalence Rate 0.10% 0.34% 0.24% 0.14% 0.12% 0.05% 0.07%

 

HAV Testing Uptake and Serology Results

A total of 3,143 HAV serology tests were recorded among new admissions for 2005-2006. Adjusting for the proportion of new admissions in Web-IDSS (59%) and assuming that all HAV serology tests are captured, the lowest estimate of HAV testing uptake among new admissions for 2005-2006 is 32% (Table 4.2). However, among Web-IDSS data (see Appendix C, Table C.2.i, C.2.iii), HAV testing was higher among females (68.2%) compared to males (53.0%). Among males, the highest testing rate on admission was seen in Prairies (70.6%) and lowest in Quebec (20.0%). Among females, the highest rate was seen in Prairies (82.8%) and the lowest in Atlantic (29.4%) (Appendix C, Table C.2.i). A higher proportion of new admissions of Canadian-born Aboriginal origin had an HAV serology test requisition on admission (64.0%) compared to Foreign-born (55.6%) or Canadian-born non-Aboriginal (51.3%) (Appendix C, Table C.1.iii).

HAV test positivity on admission, based on a reactive serology result for any of anti-HAV IgM, HAV IgG, or total anti-HAV was 29.9% overall and slightly higher among females (34.7%) compared to males (29.5%) (see Appendix C, Table C.2.i, C.2.iii and Table 4.2). The highest HAV test positivity rate among males was in the Quebec Region (41.3%) and lowest in Prairies (27.2%). Among females, the highest HAV test positivity rate was in Pacific Region (100%) and lowest in Atlantic Region (25.0%) (Appendix C, Table C.2.i). Note that the number of females with results of serology by region is low and therefore subject to statistical variability. Test positivity on admission was highest among Foreign-born new admissions (53.8%), followed by Canadian-born Aboriginals (38.3%) and Canadian born non-Aboriginals (22.0%) (Appendix C, Table C.2.iii).

 

Figure 4.1: HAV and HBV Immunizations by Region,
Inmates, Fiscal Year 2004-2005
Figure 4.1: HAV and HBV Immunizations† by Region, Inmates, Fiscal Year 2004-2005

† - Table indicates potential number of inmates who could have been vaccinated based on the number of units purchased divided by the standard vaccination regimen for vaccine type (Vaqtq=2doses; Engerix=3 doses; Twinrix=3 doses)
Source: Financial Purchase Order data, CSC 2008

 

General Population
History of HAV Testing and Vaccination

Among general population inmates in 2005-2006, 1,213 reported a previous serology test for HAV (see Appendix C, Table C.2.ii, Table C.2.iv and Table 4.2). Reported previous test was higher among males (32.4%) compared to females (28.2%). Among males, the highest rate was seen in Prairie (39.8%) and lowest in Quebec (25.9%). Among females, the highest rate was seen in Atlantic (33.3%) and Prairie (33.0%) and the lowest in Quebec (0.0%) (Appendix C, Table C.2.ii). For general population inmates, 7.6% report testing positive on a previous HAV test and 10.9% report previous HAV treatment (see above). The results by region, gender and origin will not be discussed due to the low number of responses, but can be found in Appendix C, Tables C.2.i, C.2.ii, C.2.iii and C.2.iv.

Among general population inmates in 2005-2006, 1,386 (36.7%) reported a previous HAV vaccination (see Appendix C, Table C.2.ii, Table C.2.iv, Table 4.2). Reported previous vaccination was higher among males (37.4%) compared to females (23.0%) (Appendix C, Table C.2.ii). Among males, the highest rate was seen in Pacific (49.5%) and lowest in Ontario (14.4%). Among females, excluding Ontario12, the highest rate was seen in Pacific (33.3%) and the lowest in Atlantic and Quebec (16.7%). A higher proportion of new admissions of Canadian-born Aboriginal origin reported previous HAV vaccination (41.4%) compared to Canadian-born non-Aboriginal (19.7%) or Foreign-born (25.4%) (Appendix C, Table C.2.iv).

 

Table 4.2: Overall HAV and HBV Testing and Vaccination History, Testing and Serology among
All New Admissions and General Population Inmates, 2005 – 2006
  New Admissions (n=5,840) General Population (n=3,773)
HAV HBV HAV HBV

Source: Web-IDSS Enhanced Surveillance Data, CSC 2010
* - Testing uptake rate adjusted by 59% of all new admissions (assuming all tests are captured in Web-IDSS) represents a lowest estimate
1 – HAV: reactive for anti-HAV IgM, HAV IgG, or total anti-HAV; HBV: reactive for total anti-HBc,
anti-HBc IgM,
anti-HBe, anti-HBs, HBeAg or HBsAg.
2 – Based on the number reactive divided by the number with serological results in Web-IDSS
3 – Based on reactive serology result for anti-HAV IgM.
4 – Based on reactive serology result for anti-HBc IgM.
5 – Based on reactive serology result for anti-HBc IgM and/or HBsAg.

Testing and Vaccination History
Previous Test 1,892 2,290 1,213 1,471
Previous Test Rate 32.4% 39.2% 32.1% 39.0%
Previous Positive 68 112 92 118
Previous Positive Rate 3.6% 4.9% 7.6% 8.0%
Previous Positive Treatment 8 11 10 16
Previous Positive Treatment Rate 11.8% 9.8% 10.9% 13.6%
Vaccination History 1,359 1,850 1,386 1,764
Vaccination History Rate 23.3% 31.7% 36.7% 46.8%
Testing and Serology
Serological Tests (Number) 3,143 3,873 1,818 2,053
Serological Tests (Rate*) 32% 39%
Number with Serological Immunity1 425 904 481 767
Test Positivity2 29.9% 39.4% 41.2% 48.3%
Case Reports
Infectious (Active) HAV Cases3 12   11  
Acute HBV Cases (Active Cases)4   11   14
Infectious HBV Cases (Carriers)5   46   54

 

HAV Testing Uptake and Serology Results

Among general population inmates in 2005-2006 1,818 reported a serology test for HAV (see Appendix C, Table C.2.ii, Table C.2.iv). Testing as a general population inmate was higher among males (48.2%) compared to females (46.6%) (Appendix C, Table C.2.ii). Among males, the highest rate was seen in Atlantic (68.1%) and lowest in Pacific (25.6%). Among females, the highest rate was seen in Prairies (53.6%) and the lowest in Atlantic (25.0%) (excluding Ontario). A higher proportion of general population inmates of Foreign-born origin reported a HAV test (56.2%) compared to Canadian-born non-Aboriginal (49.9%) or Canadian-born Aboriginal (42.3%), although the proportions were comparable for all groups (see Appendix C, Table C.2.iv).

HAV test positivity as a general population inmate was 41.2% overall and higher among males (41.6%) compared to females (32.2%) (see Table 4.2 and Appendix C, Table C.2.ii). The highest HAV test positivity rate among males was in the Atlantic Region (62.1%) and lowest in Prairies (33.6%). Among females, the highest HAV test positivity rate was in Pacific Region (60.0%) and lowest in Quebec and Ontario Regions (0.0%). Note that the number of females with results of serology by region is low and therefore subject to statistical variability. Test positivity for general population was highest among Foreign-born inmates (64.3%), followed by Canadian-born Aboriginals (43.8%) and Canadian born non-Aboriginals (35.4%) (see Appendix C, Table C.2.iv).

HAV Case Reporting

The overall Web-IDSS data (Table 4.2) indicates that 23 acute HAV cases were diagnosed in 2005-2006, compared to one case reported via the IDSS system (Appendix C, Table C.1). Among new admissions, 12 cases were recorded (10 among males and 2 among females, see Appendix C, Table C.4.i). Of these 12 cases, 7 were recorded in Prairie Region, two each in Pacific and Quebec and one in Atlantic. Among general population inmates, 11 active HAV cases were recorded (10 among males and one gender unknown, see Appendix C, Table C.4.i). Of these 11 cases, four were recorded in the Pacific Region, two in the Prairie Region, two in the Atlantic Region and one each in Quebec and Ontario. Appendix C, Table C.4.ii shows the Web-IDSS data stratified by Origin. Among new admissions, there were 4 acute HAV cases in the Canadian-born non-Aboriginal and Unknown categories, three in Canadian-born Aboriginals and one foreign born case. Among general population inmates, there were 7 active HAV cases of unknown origin, two in Canadian-born Aboriginals and one each in Canadian-born non-Aboriginals and Foreign-born inmates.

Hepatitis B Virus (HBV)

New Admissions
History of HBV Testing and Vaccination

Among new admissions in 2005-2006, 2,290 (39.2%) reported a previous serology test for HBV (Table 4.2). Reported previous tests are higher among females (51.0%) compared to males (38.6%) (Appendix C, Table C.3.i). Among males, the highest rate was seen in Quebec (48.1%) and lowest in Atlantic (28.0%). Among females, the highest rate was seen in Atlantic (62.7%) and the lowest in Prairie (42.5%) (excluding Ontario). A higher proportion of new admissions of Canadian-born Aboriginal origin reported a previous HBV test (43.1%) compared to Canadian-born non-Aboriginal (38.4%) or Foreign-born (27.9%) (see Appendix C, Table C.3.iii). Overall, 4.9% of new admissions reported that they tested positive on a previous HBV test and 9.8% of these individuals report that they received treatment for HBV13.

Among new admissions in 2005-2006, 1,850 (31.7%) reported a previous HBV vaccination (Table 4.2). Reported previous vaccination was higher among females (39.6%) compared to males (31.3%)(Appendix C, Table C.3.i). Among males, the highest rate was seen in Quebec (60.3%) and lowest in Ontario (14.1%). Among females, the highest rate was seen in Pacific (61.8%) and the lowest in Prairie (31.6%) (excluding Ontario). A higher proportion of new admissions of Canadian-born Aboriginal origin reported previous HBV vaccination (36.4%) compared to Canadian-born non-Aboriginal (31.0%) or Foreign-born (15.0%) (see Appendix C, Table C.3.iii).

HBV Testing Uptake and Serology Results

A total of 3,873 HBV serology tests were recorded among new admissions for 2005-2006. Adjusting for the proportion of new admissions in Web-IDSS (59%) and assuming that all HBV serology tests are captured, the lowest estimate of HBV testing uptake among new admissions for 2005-2006 is 39% (Table 4.2). Overall, this represents 66.3% overall (see Appendix C, Table C.3.i). HBV testing was higher among females (79.5%) compared to males (65.6%). Among males, the highest testing rate on admission was seen in Quebec (86.9%) and lowest in Pacific (30.5%). Among females, the highest rate was seen in Atlantic (94.1%) and the lowest in Pacific (38.2%) (excluding Ontario). A higher proportion of new admissions of Canadian-born Aboriginal origin had an HBV serology test requisition on admission (69.5%) compared to Canadian-born non-Aboriginal (67.2%) or Foreign-born (64.8%) (see Appendix C, Table C.1.iii).

HBV test positivity on admission, based on a reactive serology result for any of total anti-HBc, anti-HBc IgM, anti-HBe, anti-HBs, HBeAg or HBsAg was 39.4% overall and higher among males (40.1%) compared to females (31.1%) (see Table 4.2 and Appendix C, Table C.3.i). The highest HBV test positivity rate among males was in the Quebec Region (54.5%) and lowest in Atlantic (15.6%). Among females, the highest HBV test positivity rate was in Quebec Region (53.1%) and lowest in Atlantic Region (15.8%) (excluding Ontario). Note that the number of females with results of serology by region is low and therefore subject to statistical variability. Test positivity on admission was highest among Foreign-born new admissions (42.7%) and lowest among Canadian-born Aboriginals (33.5%) (see Appendix C, Table C.3.iii).

General Population
History of HBV Testing and Vaccination

Among general population inmates in 2005-2006, 1471 (39.0%) reported a previous serology test for HBV (Table 4.2). Reported previous test was higher among males (39.1%) compared to females (36.8%) (Appendix C, Table C.3.ii). Among males, the highest rate was seen in Prairies (48.2%) and lowest in Ontario (30.6%). Among females, the highest rate was seen in Atlantic (75.0%) and the lowest in Quebec (8.3%) (excluding Ontario). A higher proportion of new admissions of Canadian-born Aboriginal origin reported a previous HBV test (44.9%) compared to Canadian-born non-Aboriginal (35.6%) or Foreign-born (32.3%) (see Appendix C, Table C.3.iv). For general population inmates, 8.0% report testing positive on a previous HBV test and 13.6% report previous HBV treatment. The results by region, gender and origin will not be discussed due to the low number of responses, but can be found in Appendix C, Tables C.3.i, C.3.ii, C.3.iii and C.3.iv.

Among general population inmates in 2005-2006, 1,764 (46.8%) reported a previous HBV vaccination (Table 4.2). Reported previous vaccination was higher among males (47.2%) compared to females (37.4%) (Appendix C, Table C.3.ii). Among males, the highest rate was seen in Atlantic (66.3%) and lowest in Ontario (20.5%). Among females, excluding Ontario, the highest rate was seen in Atlantic (58.3%) and the lowest in Quebec (25.0%). A higher proportion of new admissions of Canadian-born Aboriginal origin reported previous HBV vaccination (49.8%) compared to Canadian-born non-Aboriginal (46.1%) or Foreign-born (31.5%) (see Appendix C, Table C.3.iv).

HBV Testing Uptake and Serology Results

Among general population inmates in 2005-2006 2,053 reported a serology test for HBV (see Appendix C Table C.3.ii, Table C.3.iv, Table 4.2). Testing as a general population inmate was higher among females (60.3%) compared to males (54.0%) (Appendix C, Table C.3.ii). Among males, the highest rate was seen in Atlantic (66.8%) and lowest in Pacific (25.4%). Among females, the highest rate was seen in Atlantic (95.8%) and the lowest in Pacific (48.7%) (excluding Ontario). A higher proportion of general population inmates of Foreign-born origin reported an HBV test (60.0%) compared to Canadian-born non-Aboriginal (57.6%) or Canadian-born Aboriginal (48.1%) (see Appendix C, Table C.3.iv).

HBV test positivity as a general population inmate was 48.3% overall and slightly higher among males (48.6%) compared to females (45.1%) (see Table 4.2 and Appendix C, Table C.3.ii). The highest HBV test positivity rate among males was in the Atlantic Region (71.0%) and lowest in Prairies (31.8%). Among females, the highest HBV test positivity rate was in Pacific Region (70.6%) and lowest in Atlantic (33.3%) (excluding Ontario). Note that the number of females with results of serology by region is low and therefore subject to statistical variability. Test positivity for general population was highest among Foreign-born inmates (51.6%), followed by Canadian-born non-Aboriginals (49.6%) and Canadian born Aboriginals (39.5%) (see Appendix C, Table C.3.iv).

HBV Case Reporting

Web-IDSS data indicate that there were 25 acute HBV cases in 2005-2006 and 100 infectious carriers. This is compared to 15 cases reported via the IDSS system (Appendix C, Table C.1). Among new admissions, 11 cases (11 men) and 46 carriers (40 men, 6 women) were recorded (see Appendix C, Table C.4.i). The highest number of cases and carriers were reported in the Pacific Region (5 cases, 16 carriers) and the lowest number of cases and carriers were reported in the Atlantic Region (0 cases, 1 carrier). Among general population inmates, 14 active HBV cases (14 men) and 54 carriers (54 men) were recorded (see Appendix C, Table C.4.i). The highest number of HBV cases was recorded in the Quebec Region (6) and the highest number of HBV carriers was recorded in the Prairie Region (16). The lowest number of HBV cases was in the Atlantic Region (0) and the lowest number of HBV carriers was in the Pacific Region (4).

Appendix C, Table C.4.ii shows the HBV data stratified by origin. Among new admissions, there were 7 active HBV cases in the Canadian-born non-Aboriginal category, and two each among Canadian-born Aboriginals and Foreign-born. Among general population inmates, there were 6 active HBV cases in Canadian-born non-Aboriginals, two in Canadian-Born Aboriginals and one among Foreign-born. Among new admissions, there were 21 HBV carriers in the Canadian-born non-Aboriginal category, 12 among Foreign-born and 11 among Canadian-born Aboriginals. Among general population inmates, there were 18 HBV carriers in Canadian-born non-Aboriginals, 13 in Canadian-Born Aboriginals and 8 among Foreign-born.

 


Footnote

9 Note that this venipuncture often accompanies others simultaneously for other infectious diseases (i.e., HIV, HCV, etc).

10 Atlantic Region implemented an electronic workbook to track vaccinations given to inmates in 2005; so it may have been possible to validate self-reported vaccination history for some New Admissions in that region without repeating serology.

11 Previous treatment is self-reported and not validated; as there is no antiviral treatment per se for HAV, it is unclear what this positive response may entail. It may be that inmates with a previous acute HAV may have received supportive treatment for side effects, or are responding in the positive as a result of medical management such as isolation or immunoglobulin (HAIg).

12 For comparisons among females, Ontario was excluded due to a lack of data. See limitations.

13 Previous treatment is self-reported and not validated. Inmates with a previous acute HBV infection may have received treatment with antiviral medication, immunoglobulin (HBIg), treatment for side effects, or medical management such as isolation.

 

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