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INFECTIOUS DISEASE SURVEILLANCE IN CANADIAN FEDERAL PENITENTIARIES
2005-2006
PRE-RELEASE REPORT
Public Health Branch
Health Services Sector
Correctional Service Canada
Infectious Diseases Surveillance in Canadian Federal Penitentiaries 2005-2006 Pre-Release Report was prepared by the Public Health Branch, Health Services Sector of Correctional Service Canada (CSC) and is published in both English and French.
It may be quoted in whole or in part with the permission of the Correctional
Service Canada and is available on CSC’s Internet site at: http://www.csc-scc.gc.ca.
For more information, or to obtain copies of this report or other reports,
please contact:
Epidemiologist
Public Health Branch
Health Services Sector
Correctional Service Canada
340 Laurier Avenue West
Ottawa, Ontario
K1A 0P9
Canada
Telephone: (613) 943-2318
Table of Contents
- Part 1: Introduction and Methods
- Part 2: Results.
- Part 3: Discussion
Part 1: Introduction and Methods
Background
In Canada, offenders who are sentenced to incarceration for a period of two years or greater serve their time in federal correctional facilities. These facilities are operated by Correctional Service Canada (CSC) and inmates residing in federal institutions are provided with essential health care which conforms to professionally accepted standards1. This includes screening, testing and treatment for tuberculosis and bloodborne and sexually transmitted infections.
This pre-release report includes, by order of presentation, surveillance data for the federal inmate population on human immunodeficiency virus (HIV), hepatitis C (HCV), hepatitis A (HAV), hepatitis B (HBV), sexually transmitted infections (STI), and tuberculosis (TB). The data on TB also includes CSC staff. The pre-release report summarizes the analysis of surveillance data from January 1st 2005 to December 31st 2006 and contains cumulative national data which should be considered provisional until the release of the full report.
This report is organized by disease (or pathogen). Data for HIV, HCV, HBV, HAV and STI are from the CSC Infectious Disease Surveillance System (IDSS), which is an aggregate register of monthly serology screening tests and case reports. Tuberculosis assessment data for inmates that are presented in this report were exported from CSC’s line-listed Web-enabled Infectious Disease Surveillance System (Web-IDSS). TB treatment and active case data for inmates is from the IDSS. Tuberculosis assessment data for staff were exported from the staff version of Web-IDSS which is located at the Public Health Agency of Canada (PHAC). TB treatment and active case data for staff are not presented in this report as this data is not available to CSC because staff are assessed and treated for TB by their personal physician.
Data on testing, prevalence, treatment, and releases to the community are presented (where available – some data are only available for certain diseases). In some cases, the data is disaggregated by gender. Since the IDSS data are aggregate institutional data, “gender” was determined according to the sex of the majority housed at the institution. In a very few circumstances female inmates may be housed for short periods in institutions for males. This may lead to some, albeit negligible, misclassification bias. Missing gender information on tuberculosis surveillance forms leads to a gender unknown classification; this category has been suppressed in this report for clarity of presentation.
Populations
The total number of individuals comprising the annual incarcerated population under health surveillance for 2005 – 2006 is shown in Table 1.i. The number of new admissions rose 5% from 2005 (4,819) to 2006 (5,079). An overall rise in population from 2005 – 2006 was accompanied by a corresponding increase in both male and female populations. New admissions are defined for the purpose of this report as new warrants of committal issued in the calendar year, as reported by CSC’s Offender Management System.
Table 1.i: Federal Incarcerated Populations Under Surveillance, CSC 2005-2006
| 2005† | 2006‡ | |||||
|---|---|---|---|---|---|---|
| Males | Females | Total | Males | Females | Total | |
| Canada | 16,384 | 657 | 17,041 | 17,611 | 748 | 18,359 |
| New admissions | 4,549 | 270 | 4,819 | 4,776 | 303 | 5,079 |
| General population | 11,835 | 387 | 12,222 | 12,835 | 445 | 13,280 |
† - source: Performance Assurance, CSC, as of April 6th,
2006
‡ - source: Performance Assurance, CSC, as of July 15th,
2007
Screening and Testing
As per CSC policy (Commissioner’s Directive 821, section 23), all inmates are offered screening upon admission for infectious diseases including HIV, HCV, HAV, HBV, STI and TB. Screening is an assessment of risk behaviours by means of a questionnaire and a physical examination. Although this screening is offered to all inmates, some refuse to take part. Inmates are recommended testing services (a blood test) if they are deemed to be at risk for an infectious disease based upon their screening results or otherwise request a test. The IDSS does not provide information on the number of inmates who accept or refuse screening for infectious diseases; rather, only data on the number of blood tests drawn to test for infection status. All screening and testing is voluntary, except where an inmate is suspected of having active TB.
For general population inmates, screening and testing for tuberculosis is offered on an annual basis. Testing for HIV, viral hepatitis and STI is available to general population inmates upon request at any time during incarceration.
For staff, TB screening is conducted by nurses from Health Canada’s Public Service Occupational Health Program and the screening forms are sent to PHAC for data entry and analysis. TB screening is voluntary unless active disease is suspected. Any TB testing provided to CSC staff by their personal physician would not be included in the data presented in this report.
Data presented for HIV and viral hepatitis are based on laboratory confirmation of respective antibody testing. Note that during the period of time under surveillance in this report, some HCV positive test results may have used follow-up PCR to confirm infectiousness. For HIV and HCV, only the results of screening tests for inmates of previously negative or unknown status are reported, not the results of confirmatory testing for inmates who are already aware of their positive status. For STI, all diagnosed/treated cases are reported, regardless if the case was laboratory-confirmed or diagnosed/treated on the basis of symptoms (i.e. a clinical case). Latent tuberculosis infection (LTBI) is reported on the basis of positive tuberculin skin test results. Active tuberculosis cases reported are those diagnosed by a TB medical specialist based upon the Canadian Tuberculosis Standards (2005 revision).
Treatment
The number of inmates on treatment for HIV, HCV and LTBI is submitted via the CSC IDSS system. For HIV and HCV, each institution reports the number of inmates initiated on treatment in a given month. For HIV, HCV and LTBI, each institution reports the number of inmates on treatment in a given month. Thus it is possible to calculate the average number of inmates on treatment for a particular disease per month by region, and by aggregating across the five regions, for CSC overall.
Since antiretrovirals do not cure HIV infection, HIV positive individuals generally continue on treatment for an indeterminate period of time. It is therefore possible to calculate HIV treatment uptake by dividing the average number on HIV treatment per month by the average number of HIV positive inmates per month.
In contrast, inmates on treatment for HCV and LTBI have a set course of treatment which, provided treatment is successful, removes their infection2. It is therefore NOT possible to calculate HCV and LTBI treatment uptake from IDSS data since it is impossible to determine the total number of individuals who are successfully treated3.
TB treatment provided to CSC staff is by personal physicians in the community and therefore not included in the data presented in this report.
Part 2: Results
1. Human Immunodeficiency Virus (HIV)
Participation in Testing
Table 1.1 shows the total number of HIV tests reported for inmates between 2000 and 2006 by inmate status. There were 6,106 HIV tests in 2005 and 6,155 in 2006.
Table 1.1: Total Number of HIV Tests, Inmates, 2000 - 2006
| 2000 | 2001 | 2002 | 2003 | 2004 | 2005 | 2006 | |
|---|---|---|---|---|---|---|---|
| New Admissions | |||||||
| Population | 4,302 | 4,288 | 4,159 | 4,238 | 4,413 | 4,819 | 5,079 |
| HIV test requisitions | 1,596 | 1,768 | 2,317 | 2,059 | 2,112 | 2,418 | 2,645 |
| HIV testing uptake | 37.1% | 41.2% | 55.7% | 48.6% | 47.9% | 50.2% | 52.1% |
| General Population† | |||||||
| Population | 12,363 | 12,479 | 12,295 | 12,179 | 13,107 | 12,222 | 13,280 |
| HIV test requisitions | 2,573 | 2,770 | 3,505 | 3,771 | 3,567 | 3,688 | 3,510 |
| HIV testing uptake | 20.8% | 22.2% | 28.5% | 31.0% | 27.2% | 30.2% | 26.4% |
| Total number of HIV tests | 4,169 | 4,538 | 5,822 | 5,830 | 5,679 | 6,106 | 6,155 |
† - includes temporary detainees
Source: IDSS Aggregate Surveillance Data, CSC 2010
HIV Prevalence
The year-end point-prevalence estimate for HIV among inmates in Canadian federal penitentiaries 1999 – 2006 is shown in Figure 1.1. The year-end HIV prevalence was 1.67% in 2005 (N=204) and 1.64% in 2006 (N=218).
The year-end point prevalence shows variance by gender (see Figure 1.2). The estimated HIV prevalence among women was 2.84% in 2005 and 4.49% in 2006. Women continue to have higher rates of HIV infection compared to men. The estimated HIV prevalence among men was 1.63% in 2005 and 1.54% in 2006.
Figure 1.1: Year-end Prevalence of HIV, Inmates, 1999 – 2006±
± - For data 1990-1998 see surveillance report for 2002-2004 (CSC, 2008).
Source: IDSS Aggregate Surveillance Data, CSC 2010
Figure 1.2: Year-end Prevalence of HIV by Gender, Inmates, 2000 – 2006
Source: IDSS Aggregate Surveillance Data, CSC 2010
HIV Treatment
For each month, the IDSS provides the number of inmates initiated on treatment and those currently on treatment for HIV infection. Table 1.2 shows that the number of inmates initiated on treatment was 68 in 2000, 50 in 2005 and 70 in 2006. Overall the proportion of HIV positive inmates on therapy was 54.2% in 2005 and 52.9% in 2006.
Table 1.2: HIV Treatment Initiation and Uptake, Inmates, 2000 - 2006
| 2000 | 2001 | 2002 | 2003 | 2004 | 2005 | 2006 | |
|---|---|---|---|---|---|---|---|
| Number of Inmates Initiated on HIV Treatment | 68 | 41 | 46 | 40 | 55 | 50 | 70 |
| Average Number of HIV Positive Inmates per Month [A] | 197 | 215 | 233 | 232 | 198 | 203 | 215 |
| Average Number on HIV Treatment per Month [B] | 119 | 122 | 128 | 121 | 116 | 110 | 114 |
| Treatment Uptake (percent) [B/A*100] | 60.3% | 56.9% | 55.0% | 52.1% | 58.7% | 54.2% | 52.9% |
| Males | 61.2% | 60.2% | 56.0% | 52.4% | 58.5% | 55.3% | 53.8% |
| Females | 43.5% | 13.2% | 35.6% | 48.4% | 60.5% | 40.3% | 41.3% |
Source: IDSS Aggregate Surveillance Data, CSC 2010
Releases to the Community - HIV
The majority of federal inmates serve determinate sentences and are eventually released to the community. Table 1.3 shows that the total number of inmates known to be living with HIV released to the community was 175 in 2005 and 193 in 2006.
Table 1.3: Number of Known HIV Positive Inmates Released to the Community, 2000 - 2006
| 2000 | 2001 | 2002 | 2003 | 2004 | 2005 | 2006 | |
|---|---|---|---|---|---|---|---|
| Number of known HIV positive inmates released to the community | 162 | 173 | 183 | 205 | 214 | 175 | 193 |
Source: IDSS Aggregate Surveillance Data, CSC 2010
2. Hepatitis C (HCV)
Participation in Testing
Table 2.1 shows the total number of HCV tests for inmates between 2000 and 2006 by inmate status. There were 5,489 tests for HCV in 2005 and 5,509 in 2006.
Table 2.1: Total Number of HCV Tests, Inmates, 2000 - 2006
| 2000 | 2001 | 2002 | 2003 | 2004 | 2005 | 2006 | |
|---|---|---|---|---|---|---|---|
| New Admissions | |||||||
| Population | 4,302 | 4,288 | 4,159 | 4,238 | 4,413 | 4,819 | 5,079 |
| HCV test requisitions | 1,583 | 1,908 | 2,307 | 1,987 | 2,074 | 2,367 | 2,511 |
| HCV testing uptake | 36.8% | 44.5% | 55.5% | 46.9% | 47.0% | 49.1% | 49.4% |
| General Population† | |||||||
| Population | 12,363 | 12,479 | 12,295 | 12,179 | 13,107 | 12,222 | 13,280 |
| HCV test requisitions | 2,151 | 2,512 | 3,423 | 3,887 | 3,432 | 3,122 | 2,998 |
| HCV testing uptake | 17.4% | 20.1% | 27.8% | 31.9% | 26.2% | 25.5% | 22.6% |
| Total number of HCV tests | 3,734 | 4,420 | 5,730 | 5,874 | 5,506 | 5,489 | 5,509 |
Source: IDSS Aggregate Surveillance Data, CSC 2010
† - includes temporary detainees
HCV Prevalence
The year-end point-prevalence estimate for HCV is shown in Figure 2.1. The number of HCV cases reported at year-end was 3,581 in 2005 and 3,661 in 2006, an increase in prevalence of 58% since 2000. HCV prevalence was 29.3% in 2005 and 27.6% in 2006.
The year-end HCV point prevalence also shows variance by gender (see Figure 2.2). The estimated HCV prevalence among women was 39.5% in 2005 and 36.0% in 2006. The estimated HCV prevalence among men was 29.0% in 2005 and 27.3% in 2006.
Figure 2.1: Year-end Prevalence of HCV, Inmates, 1999-2006±
± - For data 1990-1998 see surveillance report for 2002-2004 (CSC,
2008).
Source: IDSS Aggregate Surveillance Data, CSC 2010
Figure 2.2: Year-end Prevalence of HCV by Gender, Inmates, 2000 – 2006
Source: IDSS Aggregate Surveillance Data, CSC 2010
HCV Treatment
For each month, the IDSS provides the number of inmates initiated on treatment and those currently on treatment for HCV infection. The number of inmates initiated on HCV treatment was 267 in 2005, and 370 in 2006 (Table 2.2). The average number of inmates on HCV treatment in any given month was 40 in 2000, 136 in 2005 and 184 in 2006.
Table 2.2: HCV Treatment: Treatment Initiation and Uptake, Inmates, 2000 - 2006
| 2000 | 2001 | 2002 | 2003 | 2004 | 2005 | 2006 | |
|---|---|---|---|---|---|---|---|
| Number of inmates initiated on HCV treatment | 91 | 123 | 163 | 271 | 252 | 267 | 370 |
| Average number of HCV positive inmates per month | 2,253 | 2,916 | 3,128 | 3,179 | 3,252 | 3,572 | 3,621 |
| Average number of inmates on HCV treatment per month | 40 | 56 | 90 | 120 | 129 | 136 | 184 |
Source: IDSS Aggregate Surveillance Data, CSC 2010
Releases to the Community - HCV
The majority of federally incarcerated inmates serve determinate sentences and are eventually released to the community. Table 2.3 shows that the total number of known HCV positive inmates released to the community was 2,065 in 2005 and 2,183 in 2006.
Table 2.3: Number of Known HCV Positive Inmates Released to the Community, 2000 - 2006
| 2000 | 2001 | 2002 | 2003 | 2004 | 2005 | 2006 | |
|---|---|---|---|---|---|---|---|
| Number of HCV positive inmates released to the community | 1,156 | 1,506 | 1,856 | 2,354 | 2,472 | 2,065 | 2,183 |
Source: IDSS Aggregate Surveillance Data, CSC 2010
3. Hepatitis A (HAV) and Hepatitis B (HBV)
HAV and HBV Case Reporting
HAV case reporting via the aggregate IDSS system commenced in 2005. Table 3.1 shows the 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 six HBV cases reported in 2005 and nine in 2006. The overall prevalence rate for acute HBV was 0.05% in 2005 and 0.07% in 2006.
CSC inmates are offered vaccination for both HAV and HBV – however data for this time period are based on purchase data and are limited. A more detailed description of these data will be presented in the full report.
Table 3.1: Number of Hepatitis A and Hepatitis B Cases, Inmates, 2000 - 2006
| 2000 | 2001 | 2002 | 2003 | 2004 | 2005 | 2006 | |
|---|---|---|---|---|---|---|---|
| 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% |
Source: IDSS Aggregate Surveillance Data, CSC 2010
4. Sexually Transmitted Infections (STI)
STI Case Reporting
The IDSS provides the number of cases diagnosed with genital chlamydia, gonorrhea, syphilis, and ‘other STI’ (which includes herpes simplex, genital warts, and any other non-specific STI such as urethritis). The overall frequency of cases reported and the corresponding prevalence rates for STI by gender are shown in Table 4.1. The trends in prevalence rates over time for the different STI are displayed in Figure 4.1.
Table 4.1: Reported STI Cases and Prevalence (percentage), Inmates, 2000 - 2006
| STI (N/%) | 2000 | 2001 | 2002 | 2003 | 2004 | 2005 | 2006 |
|---|---|---|---|---|---|---|---|
| Chlamydia | 21 (0.17%) |
23 (0.18%) |
53 (0.43%) |
58 (0.48%) |
53 (0.40%) |
92 (0.75%) |
95 (0.72%) |
| Male | 19 (0.16%) |
21 (0.17%) |
49 (0.41%) |
55 (0.46%) |
48 (0.38%) |
87 (0.74%) |
87 (0.68%) |
| Female | 2 (0.64%) |
2 (0.60%) |
4 (1.31%) |
3 (0.89%) |
5 (1.23%) |
5 (1.29%) |
8 (1.80%) |
| Gonorrhea | 11 (0.09%) |
13 (0.10%) |
20 (0.16%) |
7 (0.06%) |
11 (0.08%) |
11 (0.09%) |
20 (0.15%) |
| Male | 11 (0.09%) |
11 (0.09%) |
19 (0.16%) |
6 (0.05%) |
7 (0.06%) |
10 (0.08%) |
19 (0.15%) |
| Female | 0 (0.00%) |
2 (0.60%) |
1 (0.33%) |
1 (0.30%) |
4 (0.98%) |
1 (0.26%) |
1 (0.22%) |
| Syphilis | 0 (0.00%) |
0 (0.00%) |
3 (0.02%) |
4 (0.03%) |
10 (0.08%) |
6 (0.05%) |
16 (0.12%) |
| Male | 0 (0.00%) |
0 (0.00%) |
3 (0.03%) |
3 (0.03%) |
9 (0.07%) |
6 (0.05%) |
14 (0.11%) |
| Female | 0 (0.00%) |
0 (0.00%) |
0 (0.00%) |
1 (0.30%) |
1 (0.25%) |
0 (0.0%) |
2 (0.45%) |
| Other STI | 60 (0.49%) |
35 (0.28%) |
53 (0.43%) |
85 (0.70%) |
91 (0.69%) |
66 (0.54%) |
61 (0.46%) |
| Male | 20 (0.17%) |
10 (0.08%) |
45 (0.38%) |
71 (0.60%) |
69 (0.54%) |
50 (0.42%) |
35 (0.27%) |
| Female | 40 (12.74%) |
25 (7.53%) |
8 (2.61%) |
14 (4.14%) |
22 (5.41%) |
16 (4.13%) |
26 (5.84%) |
Source: IDSS Aggregate Surveillance Data, CSC 2010
Figure 4.1: STI Prevalence in Canadian Federal Penitentiaries, Inmates, 2000 - 2006
Source: IDSS Aggregate Surveillance Data, CSC 2010
5. Tuberculosis (TB) among Inmates
Participation in Assessment
Inmate participation in TB screening from 1998 – 2006 is shown in Table 5.1. Among inmates participation in TB assessment was 81.8% in 2005 and 79.5% in 2006.
Table 5.1: Participation1 in TB Assessment, Inmates, 1998-2006
| 1998 | 1999 | 2000 | 2001 | 2002 | 2003 | 2004 | 2005 | 2006 | |
|---|---|---|---|---|---|---|---|---|---|
| Inmates | 12,413 (86.2%) |
13,399 (77.4%) |
13,013 (78.1%) |
13,197 (78.7%) |
13,223 (80.4%) |
13,460 (82.0%) |
13,470 (76.9%) |
13,938 (81.8%) |
14,588 (79.5%) |
1 – Participation rate calculated by adding annual new admissions
to the inmate population as of January 1st of that year.
Source: Web-IDSS Enhanced Surveillance Data, CSC 2010
Tuberculin Skin Test (TST) Converters and Conversion Rate
Analysis of the previous TST history for inmates who tested positive on an ongoing negative assessment allows the estimation of the conversion rate. A converter is defined as a person with a previously documented negative TST result who now has a positive TST result. Figure 5.1 shows the number of inmates who converted their TST and the corresponding conversion rate for each year from 1999-2006. These data show that the estimated TST conversion rate among inmates was 0.90% in 2005 and 0.89% in 2006.
Figure 5.1: TST Converters and Conversion Rates, Inmates, 1999-2006
Source: Web-IDSS Enhanced Surveillance Data, CSC 2010
Latent TB Infection (LTBI)
The overall proportion of inmates considered to be infected with Mycobacterium tuberculosis is calculated by combining all those with a positive TST (the number positive on the initial assessment, those newly positive, and those who previously tested positive) divided by the total number of individuals tested.
Figure 5.2 shows the proportion of LTBI by gender for 1998-2006. Among males, the proportion having LTBI was 16.1% in 2005 and 16.8% in 2006. Among females, the proportion having LTBI was 8.4% in 2005 and 11.3% in 2006.
Figure 5.2: Latent TB Infection by Gender, Inmates, 1998 - 2006
Source: Web-IDSS Enhanced Surveillance Data, CSC 2010
LTBI Treatment
Table 5.2 shows the number of inmates with LTBI and the average monthly number of inmates on prophylactic therapy for LTBI for 1999 to 2006. The total number of inmates with LTBI has trended downwards from 2946 in 1999 to 2421 in 2006 while the number of inmates on LTBI therapy per month has trended up from 44 in 1999 to 103 in 2006.
Table 5.2: Average Monthly Number of Inmates on Prophylactic Therapy for LTBI, 1999 - 2006
| 1999 | 2000 | 2001 | 2002 | 2003 | 2004 | 2005 | 2006 | |
|---|---|---|---|---|---|---|---|---|
| Number of inmates with LTBI | 2946 | 2654 | 2760 | 2494 | 2532 | 2259 | 2198 | 2421 |
| Average number on LTBI therapy per month | 44 | 57 | 72 | 64 | 49 | 84 | 99 | 103 |
Source: IDSS Aggregate Surveillance Data, CSC 2010
Active Tuberculosis Disease
Cases of active tuberculosis disease (Active TB) are reported via the CSC IDSS (see Figure 5.3). The number of active TB cases diagnosed and reported among inmates in CSC was 7 in 2005 and 3 in 2006. These case reports translate into yearly case rates per 100,000 of 41.1, and 16.3 respectively.
Since the absolute number of active TB cases is small, a three-year moving average was calculated (see Figure 5.3). This has the effect of smoothing the variability in the small number of cases year to year. The centred 3-year moving average was 23.6 / 100,000 in 2004 and 22.9 / 100,000 in 2005.
Figure 5.3: Active TB Case Frequency and Rate, Inmates, 1998 - 2006
* - Case Rate: rate per 100,000
** - % LTBI: Proportion having LTBI (percent)
Source: IDSS Aggregate Surveillance Data, CSC 2010
6. Tuberculosis (TB) among Staff
Participation in Assessment
Participation in TB assessment for CSC staff 1998 – 2006 is shown in Table 6.1. Among staff, the participation rate was 13.5% in 2005 and 17.9% in 2006.
Table 6.1: Participation in TB Assessment, Staff, 1998-2006
| 1998 | 1999 | 2000 | 2001 | 2002 | 2003 | 2004 | 2005 | 2006 | |
|---|---|---|---|---|---|---|---|---|---|
| Staff | 4,319 (38.6%) |
3,986 (28.2%) |
3,327 (20.6%) |
3,299 (19.8%) |
2,969 (17.2%) |
3,278 (19.6%) |
2,376 (14.0%) |
1,995 (13.5%) |
2,939 (17.9%) |
Source: Web-IDSS Enhanced Surveillance Data, CSC 2010
Tuberculin Skin Test (TST) Converters and Conversion Rate
Analysis of the previous TST history for staff who tested positive on an ongoing negative assessment allows the estimation of the conversion rate. A converter is defined as a person with a previously documented negative TST result who now has a positive TST result. Figure 6.1 shows the number of staff who converted their TST and the corresponding conversion rate for each year from 1999-2006. These data show that the estimated TST conversion rate among staff was 0.82% in 2005 and 0.66% in 2006.
Figure 6.1: TST Converters and Conversion Rates, Staff, 1999-2006
Source: Web-IDSS Enhanced Surveillance Data, CSC 2010
Latent Tuberculosis Infection (LTBI)
The overall proportion of staff considered to be infected with Mycobacterium tuberculosis is calculated by combining all those with a positive TST (the number positive on the initial assessment, those newly significant, and those who previously tested positive) divided by the total number of individuals tested.
Figure 6.2 shows the proportion of LTBI by gender among staff for 1998-2006. Among males, the proportion having LTBI was 6.9% in 2005 and 6.4% in 2006. Among females, the proportion having LTBI was 6.3% in 2005 and 6.5% in 2006.
Figure 6.2: Latent TB Infection by Gender, Staff, 1998 - 2006
Source: Web-IDSS Enhanced Surveillance Data, CSC 2010
Part 3: Discussion
Summary of Diseases / Pathogens
Data on infectious disease testing was presented for HIV, HCV, and tuberculosis. In 2005-6 the testing uptake for HIV and HCV on admission was roughly 50% and for general population inmates was between 20-30%. We expect testing rates to be higher on admission as all inmates are offered screening at this time whereas general population inmates are not systematically offered testing, however can request it at any point during incarceration. Inmates who did not test on admission might not have been at risk for HIV / HCV or might have tested recently in the community or in a provincial / territorial correctional facility as per national guidelines4. Almost 80% of inmates and about 18% of staff were screened for tuberculosis. The participation rate for staff may be underestimated since a TB test done by their personal physician would not be reflected in the data. While the scope of the inmate TB screening program is to screen all inmates, staff members working at headquarter offices rather than in institutions are less likely to be included in TB screening.
The prevalence rates for HIV, HCV, HAV, HBV, STI and TB in the federal inmate population presented above tend to be higher than the general Canadian population5. At CSC, hepatitis C presents the highest disease burden, with between 27-30% of the total inmate population infected. Overall HIV prevalence is around 1.6-1.7% and HAV/HBV/STI prevalence is less than one percent for each disease. The prevalence rates for these diseases are generally much higher in the female inmate population than for male inmates.
The LTBI prevalence in inmates is about 16% and in staff is about 7%. LTBI rates are higher for males than females. The number of inmates with LTBI has trended downwards from 1999-2006; however, the number of inmates on LTBI therapy per month has more than doubled during this timeframe. While CSC only has a small number of active TB cases in inmates each year the active TB rate is much higher than in the general Canadian population. Around 1% of inmates and staff convert their TST each year which indicates that TB transmission is occurring in CSC institutions.
The overall proportion of HIV positive inmates on treatment was about 53-54%. While a treatment uptake of 100% may seem optimal, there may be a number of reasons (e.g., deferral of treatment, discontinuation due to side-effects or drug resistance) for an inmate NOT being on treatment in any given month.6 In 2005-6 about 160 inmates were on HCV treatment and 100 inmates were on LTBI treatment in any given month; however IDSS data cannot be used to determine an estimate of overall HCV or LTBI treatment coverage. The number of inmates on treatment for HCV and LTBI in a given month has increased over time which is an indication of the increasing amount of resources, such as nurse time, which are being directed to treating individuals with these conditions.
Limitations
The data presented in this report are subject to a number of limitations. The IDSS data are aggregate and rely on nurses to provide the data at the end of each month. In the absence of a standardized electronic health record, this is a “pencil and paper” task. Tracking inmate transfers on a monthly basis requires a review of transfer lists and cross-referencing these against other lists, again manually. In addition, there are some instances (e.g. an HCV case who is transferred to a provincial facility for court purposes or to a community hospital), which are not captured by the IDSS, and may lead to differences in how the data are recorded between institutions. An administration guide for the IDSS is available.
The categorization of inmates into ‘new admission’ and ‘general population’ may result in some misclassification errors. In some instances, new admissions may be immediately removed to segregation, either as result of their security classification or as a result of behaviour. In this case, the inmate is not necessarily available to health services, and special arrangements must be made to ensure the nurse conducts the health assessment.
It may also happen that a newly-received inmate is interviewed and tests are requested while he/she is still in an admission unit, but the test results are not received until the inmate has transferred out to another institution (where he/she is now considered a general population inmate). If the institution receiving the test results reports the results, the test would be counted for a general population inmate rather than a new admission. This matter is further complicated in the case of women inmates, as one institution per region handles admissions and houses general population females at various security levels. Consequently, the distinction between ‘new admission’ and ‘general population’ is less clear.
A major source of variability in the tuberculosis screening data is the tuberculin skin test itself. Inter-operator variability in tuberculin administration and reading the resulting induration may result in differences in TST outcomes. There may also be some variation in the interpretation of the test (i.e., what constitutes a positive result). Cold-chain protocols must also be strictly followed in order to preserve the viability of the purified protein derivative.
Future Directions
In 2005, CSC introduced enhanced screening forms for bloodborne and sexually transmitted infections. The results of the enhanced screening are captured in the Web-IDSS which will eventually replace the aggregate data captured in the current IDSS. Future reports will utilize analysis of these records to examine case reports in more detail, and over time, to examine other pertinent questions, such as screening uptake and risk factors among new admissions; and to estimate seroconversion rates for bloodborne and sexually transmitted infections among inmates in CSC institutions. These results are being prepared for the full surveillance report on infectious disease in federal penitentiaries for 2005-2006 and for subsequent reports and analysis.
2 HCV treatment usually consists of 24-48 weeks of combination therapy and LTBI Treatment usually consists of a nine-month regimen of isoniazid. However, the course of treatment for each individual is determined by the institutional physician.
3 Dividing the average number of inmates on therapy in a given month by the total number of inmates infected with the pathogen results in an under estimate of treatment coverage; similarly, the same number divided by 12 is an inappropriate denominator for this estimate.
4 For national guidelines for HIV and HCV visit the guidelines page on the PHAC website: http://www.phac-aspc.gc.ca/dpg-eng.php.
5 Prevalence data on reportable diseases in Canada are reported by PHAC: http://www.phac-aspc.gc.ca/.
6 Reasons for treatment interruptions or treatment delays among HIV positive inmates were explored in the 2007 National Inmate Survey which can be found on the CSC website: http://www.csc-scc.gc.ca/text/rsrch/reports/r211/r211-eng.pdf.
