Infectious Diseases Surveillance in Canadian Federal Penitentiaries 2007-2008

Pre-Release Report

Public Health Branch
Health Services Sector
Correctional Service Canada

Infectious Diseases Surveillance in Canadian Federal Penitentiaries 2007-2008 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:

Manager, Surveillance and Epidemiology
Public Health Branch
Health Services Sector
Correctional Service Canada
340 Laurier Avenue West
Ottawa, Ontario
K1A 0P9
Canada
Telephone: (613) 943-2318

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 standardsFootnote 1.  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 2007 to December 31st 2008 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 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 2007 – 2008 is shown in Table 1.i.  The number of new admissions decreased very slightly from 2007 (5,005) to 2008 (4,962).  An overall decrease in population from 2007 – 2008 was accompanied by a corresponding decrease 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 Corporate Reporting System.

Table 1.i:
Federal Incarcerated Populations Under Surveillance, CSC 2007-2008
  2007 2008
Males Females Total Males Females Total
Canada 17,929 805 18,734 17,088 803 17,891
New admissions 4,700 305 5,005 4,626 336 4,962
General population 13,229 500 13,729 12,462 467 12,929

- source: Corporate Reporting System, CSC August 2008
- source: Corporate Reporting System, CSC March 2012

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 consists of a preliminary 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.  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 and / or treated cases are reported, regardless if the case was laboratory-confirmed, diagnosed based on clinical symptoms, or treated presumptively.  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.

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 infectionFootnote 2.  It is therefore NOT possible to calculate meaningful HCV and LTBI treatment uptake metrics from the aggregate IDSS data since it is impossible to determine the total number of individuals who are successfully treatedFootnote 3.

TB treatment is provided to CSC staff 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 2008 by inmate status.  There were 5,937 HIV tests in 2007 and 6,011 in 2008. 

Table 1.1:
Total Number of HIV Tests, Inmates, 2000 - 2008
  2000 2001 2002 2003 2004 2005 2006 2007 2008
New Admissions
Population 4,302 4,288 4,159 4,238 4,413 4,819 5,079 5,005 4,962
HIV test requisitions 1,596 1,768 2,317 2,059 2,112 2,418 2,645 2,479 2,870
HIV testing uptake 37.1% 41.2% 55.7% 48.6% 47.9% 50.2% 52.1% 49.5% 57.8%
General Population
Population 12,363 12,479 12,295 12,179 13,107 12,222 13,280 13,729 12,929
HIV test requisitions 2,573 2,770 3,505 3,771 3,567 3,688 3,510 3,458 3,141
HIV testing uptake 20.8% 22.2% 28.5% 31.0% 27.2% 30.2% 26.4% 25.2% 24.3%
Total number of HIV tests 4,169 4,538 5,822 5,830 5,679 6,106 6,155 5,937 6,011

† - includes temporary detainees
Source:  IDSS Aggregate Surveillance Data, CSC 2011

HIV Prevalence

The year-end point-prevalence estimate for HIV among inmates in Canadian federal penitentiaries 1999 – 2008 is shown in Figure 1.1.  The year-end HIV prevalence was 1.84% in 2007 (N=253) and 1.72% in 2008 (N=222). 

The year-end point prevalence shows variance by gender (see Figure 1.2). The estimated HIV prevalence among women was 5.20% in 2007 and 4.71% in 2008.  Women continue to have higher rates of HIV infection compared to men.  The estimated HIV prevalence among men was 1.72% in 2007 and 1.60% in 2008.

Figure 1.1: Year-end Prevalence of HIV, Inmates, 1999 – 2008±

Description of Figure 1.1:

Source:  IDSS Aggregate Surveillance Data, CSC 2011

Summary: Figure 1.1 shows the number of HIV cases and the year-end HIV prevalence rate among inmates for each year between 1999 and 2008. HIV prevalence among inmates was relatively stable over this period, ranging between 1.43% in 2004 and 2.04% in 2002.  In 2007, 253 inmates were known to be HIV positive and the HIV point-prevalence estimate was 1.84%. In 2008, the number of HIV cases and HIV point-prevalence declined slightly, to 222 and 1.72% respectively.

Data Table:

  1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
HIV Cases 196 214 223 251 234 188 204 218 253 222
HIV Prevalence 1.65% 1.70% 1.80% 2.04% 1.92% 1.43% 1.67% 1.64% 1.84% 1.72%

Figure 1.1: Year-end Prevalence  of <abbr>HIV</abbr>, Inmates, 1999 – 2008±

± - For data 1990-1998 see surveillance report for 2002-2004 Footnote 4
Source:  IDSS Aggregate Surveillance Data, CSC 2011

Figure 1.2: Year-end Prevalence of HIV by Gender, Inmates, 2000 – 2008

Description of Figure 1.2:

Source: IDSS Aggregate Surveillance Data, CSC 2011

Summary:
Figure 1.2 shows gender-specific HIV prevalence rates among inmates for each year between 2000 and 2008. Women consistently had higher rates of HIV infection and more variability in HIV prevalence estimates compared to men. HIV prevalence among women in 2007 and 2008 at 5.20% and 4.71% respectively was about three times that among men at 1.72% and 1.60% respectively.

Data Table:

  2000 2001 2002 2003 2004 2005 2006 2007 2008
FEMALE 5.00% 4.70% 4.25% 4.73% 3.44% 2.84% 4.49% 5.20% 4.71%
MALE 1.60% 1.70% 1.99% 1.84% 1.37% 1.63% 1.54% 1.72% 1.60%
TOTAL 1.70% 1.80% 2.04% 1.92% 1.43% 1.67% 1.64% 1.84% 1.72%

Figure 1.2:  Year-end Prevalence of <abbr>HIV</abbr> by Gender, Inmates, 2000 – 2008

Source: IDSS Aggregate Surveillance Data, CSC 2011

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, 43 in 2007 and 59 in 2008.  Overall the proportion of HIV positive inmates on therapy was 54.6% in 2007 and 64.4% in 2008.

Table 1.2
HIV Treatment Initiation and Uptake, Inmates, 2000 - 2008
  2000 2001 2002 2003 2004 2005 2006 2007 2008
Number of Inmates Initiated on HIV Treatment 68 41 46 40 55 50 70 43 59
Average Number of HIV Positive Inmates per Month [A] 197 215 233 232 198 203 215 249 224
Average Number on HIV Treatment per Month [B] 119 122 128 121 116 110 114 136 147
Treatment Uptake (percent) [B/A*100] 60.3% 56.9% 55.0% 52.1% 58.7% 54.2% 52.9% 54.6% 64.4%
Males 61.2% 60.2% 56.0% 52.4% 58.5% 55.3% 53.8% 55.1% 64.3%
Females 43.5% 13.2% 35.6% 48.4% 60.5% 40.3% 41.3% 48.9% 64.5%

Source: IDSS Aggregate Surveillance Data, CSC 2011

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 164 in 2007 and 196 in 2008.

Table 1.3
Number of Known HIV Positive Inmates Released to the Community, 2000 - 2008
  2000 2001 2002 2003 2004 2005 2006 2007 2008
Number of known HIV positive inmates released to the community 162 173 183 205 214 175 193 164 196

Source: IDSS Aggregate Surveillance Data, CSC 2011

2. Hepatitis C (HCV)

Participation in Testing

Table 2.1 shows the total number of HCV tests for inmates between 2000 and 2008 by inmate status.  There were 5,584 tests for HCV in 2007 and 5,644 in 2008.

Table 2.1
Total Number of HCV Tests, Inmates, 2000 - 2008
  2000 2001 2002 2003 2004 2005 2006 2007 2008
New Admissions
Population 4,302 4,288 4,159 4,238 4,413 4,819 5,079 5,005 4,962
HCV test requisitions 1,583 1,908 2,307 1,987 2,074 2,367 2,511 2,430 2,843
HCV testing uptake 36.8% 44.5% 55.5% 46.9% 47.0% 49.1% 49.4% 48.6% 57.3%
General Population
Population 12,363 12,479 12,295 12,179 13,107 12,222 13,280 13,729 12,929
HCV test requisitions 2,151 2,512 3,423 3,887 3,432 3,122 2,998 3,154 2,801
HCV testing uptake 17.4% 20.1% 27.8% 31.9% 26.2% 25.5% 22.6% 23.0% 21.7%
Total number of HCV tests 3,734 4,420 5,730 5,874 5,506 5,489 5,509 5,584 5,644

Source:  IDSS Aggregate Surveillance Data, CSC 2011
† - 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 4,101 in 2007 and 3,907 in 2008, an increase in prevalence of 65% since 2000.  HCV prevalence was 29.9% in 2007 and 30.2% in 2008.

The year-end HCV point prevalence also shows variance by gender (see Figure 2.2).  The estimated HCV prevalence among women was 36.4% in 2007 and 34.9% in 2008.  The estimated HCV prevalence among men was 29.6% in 2007 and 30.0% in 2008. 

Figure 2.1: Year-end Prevalence of HCV, Inmates, 1999-2008±

Description of Figure 2.1:

Source:  IDSS Aggregate Surveillance Data, CSC 2011

Summary: Figure 2.1 shows the number of hepatitis C (HCV) cases and the year-end HCV prevalence rate among inmates for each year between 1999 and 2008. HCV prevalence among inmates increased steadily over this period, from 18.1% in 1999 to 30.2% in 2008. In 2007, 4,101 inmates were known to be HCV positive and the HCV point-prevalence estimate was 29.9%. In 2008, the number of HCV cases and HCV point-prevalence was 3,907 and 30.2% respectively.

Data Table

YEAR 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
FREQUENCY 2317 2542 2993 3173 3260 3303 3581 3661 4101 3907
PREVALENCE 18.1% 20.1% 23.6% 25.8% 26.8% 25.2% 29.3% 27.6% 29.9% 30.2%

± - For data 1990-1998 see surveillance report for 2002-20044
Source:  IDSS Aggregate Surveillance Data, CSC 2011

Figure 2.2: Year-end Prevalence of HCV by Gender, Inmates, 2000 – 2008

Description of Figure 2.2:

Source: IDSS Aggregate Surveillance Data, CSC 2011

Summary:
Figure 2.2 shows gender-specific HCV prevalence rates among inmates for each year between 2000 and 2008. Women consistently had higher rates of HCV infection compared to men, however this difference decreased with time. Among female inmates, HCV prevalence was at its highest in 2000 at 42.4%, and gradually declined to 36.4% in 2007 and 34.9% in 2008. Among male inmates, HCV prevalence was at its lowest in 2000 at 19.7% and gradually increased to 29.6% in 2007 and 30.0% in 2008.

Data Table

  2000 2001 2002 2003 2004 2005 2006 2007 2008
FEMALE 42.4% 41.2% 38.6% 37.0% 37.6% 39.5% 36.0% 36.4% 34.9%
MALE 19.7% 23.2% 25.5% 26.5% 24.8% 29.0% 27.3% 29.6% 30.0%
TOTAL 20.1% 23.6% 25.8% 26.8% 25.2% 29.3% 27.6% 29.9% 30.2%

Source: IDSS Aggregate Surveillance Data, CSC 2011

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 328 in 2007, and 319 in 2008 (Table 2.2).  The average number of inmates on HCV treatment in any given month was 40 in 2000, 165 in 2007 and 174 in 2008. 

Table 2.2
HCV Treatment: Treatment Initiation, Inmates, 2000 - 2008
  2000 2001 2002 2003 2004 2005 2006 2007 2008
Number of inmates initiated on HCV treatment 91 123 163 271 252 267 370 328 319

Source:  IDSS Aggregate Surveillance Data, CSC 2011

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 2,161 in 2007 and 2,254 in 2008.

Table 2.3
Number of Known HCV Positive Inmates Released to the Community, 2000 - 2008
  2000 2001 2002 2003 2004 2005 2006 2007 2008
Number of HCV positive inmates released to the community 1,156 1,506 1,856 2,354 2,472 2,065 2,183 2,161 2,254

Source: IDSS Aggregate Surveillance Data, CSC 2011

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 2008.  There were three acute HAV cases reported in 2007 and no HAV cases reported in 2008.  From a high of 43 cases diagnosed in 2001, there were 18 HBV cases reported in 2007 and 9 in 2008.  The overall prevalence rate for acute HBV was 0.13% in 2007 and 0.07% in 2008. 

Table 3.1
Number of Hepatitis A and Hepatitis B Cases, Inmates, 2000 - 2008
  2000 2001 2002 2003 2004 2005 2006 2007 2008
Total number of HAV cases -- -- -- -- -- 0 1 3 0
Acute HAV prevalence rate -- -- -- -- -- 0.00% 0.01% 0.02% 0.00%
Total number of HBV cases 13 43 30 17 16 6 9 18 9
Acute HBV prevalence rate 0.10% 0.34% 0.24% 0.14% 0.12% 0.05% 0.07% 0.13% 0.07%

Source: IDSS Aggregate Surveillance Data, CSC 2011

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 - 2008
STI 2000 2001 2002 2003 2004 2005 2006 2007 2008
  # % # % # % # % # % # % # % # % # %
Chlamydia 21 0.17% 23 0.18% 53 0.43% 58 0.48% 53 0.40% 92 0.75% 95 0.72% 92 0.67% 130 1.01%
Male 19 0.16% 21 0.17% 49 0.41% 55 0.46% 48 0.38% 87 0.74% 87 0.68% 88 0.67% 117 0.94%
Female 2 0.64% 2 0.60% 4 1.31% 3 0.89% 5 1.23% 5 1.29% 8 1.80% 4 0.80% 13 2.78%
Gonorrhea 11 0.09% 13 0.10% 20 0.16% 7 0.06% 11 0.08% 11 0.09% 20 0.15% 24 0.17% 9 0.07%
Male 11 0.09% 11 0.09% 19 0.16% 6 0.05% 7 0.06% 10 0.08% 19 0.15% 21 0.16% 6 0.05%
Female 0 0.00% 2 0.60% 1 0.33% 1 0.30% 4 0.98% 1 0.26% 1 0.22% 3 0.60% 3 0.64%
Syphilis 0 0.00% 0 0.00% 3 0.02% 4 0.03% 10 0.08% 6 0.05% 16 0.12% 10 0.07% 21 0.16%
Male 0 0.00% 0 0.00% 3 0.03% 3 0.03% 9 0.07% 6 0.05% 14 0.11% 9 0.07% 17 0.14%
Female 0 0.00% 0 0.00% 0 0.00% 1 0.30% 1 0.25% 0 0.0% 2 0.45% 1 0.20% 4 0.86%
Other STI 60 0.49% 35 0.28% 53 0.43% 85 0.70% 91 0.69% 66 0.54% 61 0.46% 87 0.63% 95 0.73%
Male 20 0.17% 10 0.08% 45 0.38% 71 0.60% 69 0.54% 50 0.42% 35 0.27% 64 0.48% 89 0.71%
Female 40 12.74% 25 7.53% 8 2.61% 14 4.14% 22 5.41% 16 4.13% 26 5.84% 23 4.60% 6 1.28%

Source: IDSS Aggregate Surveillance Data, CSC 2011

Figure 4.1 STI Prevalence in Canadian Federal Penitentiaries, Inmates, 2000 - 2008

Description of Figure 4.1:

Source: IDSS Aggregate Surveillance Data, CSC 2011

Summary:
Figure 4.1 shows the prevalence rates of several sexually transmitted infections (STI) among inmates for each year between 2000 and 2008. The prevalence rates of chlamydia, gonorrhoea, syphilis and other non-specific STI were relatively low, ranging between 0% and 1.01%. With the exception of gonorrhoea, the prevalence of all STI increased between 2007 and 2008. In 2008, the most prevalent STI was chlamydia (1.01%), followed by other non-specific STI (0.73%), syphilis (0.16%) and gonorrhoea (0.07%). 

Data Table

  2000 2001 2002 2003 2004 2005 2006 2007 2008
Chlamydia 0.17% 0.18% 0.43% 0.48% 0.40% 0.75% 0.72% 0.67% 1.01%
Gonorrhea 0.09% 0.10% 0.16% 0.06% 0.08% 0.09% 0.15% 0.17% 0.07%
Syphilis 0.00% 0.00% 0.02% 0.03% 0.08% 0.05% 0.12% 0.07% 0.16%
Other 0.49% 0.28% 0.43% 0.70% 0.69% 0.54% 0.46% 0.63% 0.73%

figure 4.1

Source: IDSS Aggregate Surveillance Data, CSC 2011

5. Tuberculosis (TB) among Inmates

Participation in Assessment

Inmate participation in TB screening from 2000 – 2008 is shown in Table 5.1.  Among inmates, participation in TB assessment was 77.8% in 2007 and 79.4% in 2008. 

Table 5.1
Participation1 in TB Assessment, Inmates, 2000-2008
  2000 2001 2002 2003 2004 2005 2006 2007 2008
Number 13,013 13,197 13,223 13,460 13,470 13,938 14,588 14,578 14,212
% 78.1% 78.7% 80.4% 82.0% 76.9% 81.8% 79.5% 77.8% 79.4%

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 2011

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 1999-2008.  These data show that the estimated TST conversion rate among inmates was 1.49% in 2007 and 1.15% in 2008.

Figure 5.1 TST Converters and Conversion Rates, Inmates, 1999-2008

Description of Figure 5.1:

Source: Web-IDSS Enhanced Surveillance Data, CSC 2011

Summary: Figure 5.1 shows the number of tuberculin skin test (TST) conversions and the year-end conversion rate among inmates for each year between 1999 and 2008. The largest number of TST conversions occurred in 2001 and 2007 with 85 and 87 conversions respectively, corresponding to the two highest conversion rates over this period at 1.64% and 1.49% respectively.  In 2008, 70 conversions were reported and the conversion rate was 1.15%

Data Table

YEAR 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
TST Converters 51 41 85 73 66 45 51 54 87 70
Conversion Rate 1.13% 0.79% 1.64% 1.45% 1.22% 0.83% 0.90% 0.89% 1.49% 1.15%

figure 5.1

Source: Web-IDSS Enhanced Surveillance Data, CSC 2011

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 1998-2008.  Among males, the proportion having LTBI was 16.9% in 2007 and 16.1% in 2008.  Among females, the proportion having LTBI was 10.6% in 2007 and 10.1% in 2008.

Figure 5.2 Latent TB Infection by Gender, Inmates, 1998 - 2008

Description of Figure 5.2:

Source: Web-IDSS Enhanced Surveillance Data, CSC 2011

Summary: Figure 5.2 shows the proportion of latent TB infections (LTBI) among male and female inmates for each year between 1998 and 2008. Overall, the proportion of inmates with LTBI decreased over time, from 22.0% in 1998 to 15.9% in 2008. In most years, a higher proportion of male inmates reported having LTBI compared to female inmates. Among males, the proportion having LTBI was 16.9% in 2007 and 16.1% in 2008. Among females, the proportion having LTBI was 10.6% in 2007 and 10.1% in 2008.

Data Table

  1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
FEMALE 22.0% 21.9% 20.5% 21.0% 19.0% 19.0% 17.1% 16.1% 16.8% 16.9% 16.1%
MALE 19.5% 22.1% 18.1% 19.8% 15.3% 13.3% 8.4% 8.4% 11.3% 10.6% 10.1%
TOTAL 22.0% 22.0% 20.4% 20.9% 18.9% 18.8% 16.8% 15.8% 16.6% 16.6% 15.9%

figure 5.2

Source: Web-IDSS Enhanced Surveillance Data, CSC 2011

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 2000 to 2008.  The total number of inmates with LTBI has trended downwards from 2,654 in 2000 to 2,255 in 2008 while the number of inmates on LTBI therapy per month has trended up from 57 in 2000 to 127 in 2008.

Table 5.2
Average Monthly Number of Inmates on Prophylactic Therapy for LTBI, 2000 - 2008
  2000 2001 2002 2003 2004 2005 2006 2007 2008
Number of inmates with LTBI 2,654 2,760 2,494 2,532 2,259 2,198 2,421 2,380 2,255
Average number on LTBI therapy per month 57 72 64 49 84 99 103 147 127

Source: IDSS Aggregate Surveillance Data, CSC 2011

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 2 in 2007 and 4 in 2008.  These case reports translate into yearly case rates per 100,000 of 10.7, and 22.4 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 16.5 / 100,000 in 2007. 

Figure 5.3 Active TB Case Frequency and Rate, Inmates, 1998 – 2008

Description of Figure 5.3 :

Source: IDSS Aggregate Surveillance Data, CSC 2011

Summary: Figure 5.3 shows the number, annual rate and three-year average rate of active TB cases among inmates for each year between 1998 and 2008. The number of active cases ranged from zero in 2001 to six cases in both 1998 and 2005.  Two inmates were diagnosed in both 2007 and 2008. This generated a three-year average case rate per 100,000 that ranged from 27.5 in 1999, to 6.0 in 2001, up to 23.5 in 2004 and down to 12.7 in 2007.

Data Table

  1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
Active TB 6 5 2 0 1 3 3 6 3 2 2
Case Rate (per 100,000) 41.7 28.9 12.0 0.0 6.1 18.3 17.1 35.2 16.3 10.7 11.2
3-yr Rate
(per 100,000)
27.5 13.6 6.0 8.1 13.8 23.5 22.9 20.7 12.7
% LTBI 22.0% 22.0% 20.4% 20.9% 18.9% 18.8% 16.8% 15.8% 16.6% 16.6% 15.9%

figure 5.3

* - Case Rate: rate per 100,000
** - % LTBI: Proportion having LTBI (percent)
Source: IDSS Aggregate Surveillance Data, CSC 2011

6. Tuberculosis (TB) among Staff

Participation in Assessment

Participation in TB assessment for CSC staff 2000 – 2008 is shown in Table 6.1.  Among staff, the participation rate was 11.8% in 2007 and 9.0% in 2008. 

Table 6.1
Participation in TB Assessment, Staff, 2000-2008
  2000 2001 2002 2003 2004 2005 2006 2007 2008
Number 3,327 3,299 2,969 3,278 2,376 1,995 2,939 1,999 1,627
% 20.6% 19.8% 17.2% 19.6% 14.0% 13.5% 17.9% 11.8% 9.0%

Source: Web-IDSS Enhanced Surveillance Data, CSC 2011

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 1999-2008.  These data show that the estimated TST conversion rate among staff was 0.20% in 2007 and 0.17% in 2008.

Figure 6.1 TST Converters and Conversion Rates, Staff, 1999-2008

Description of Figure 6.1:

Source: Web-IDSS Enhanced Surveillance Data, CSC 2011

Summary: Figure 6.1 shows the number of tuberculin skin test (TST) conversions and the year-end conversion rate among CSC staff for each year between 1999 and 2008. Since 1999, the conversion rate has gradually increased to its peak of 0.82% in 2005 with eight staff TST conversions. The conversion rate has since declined with two TST conversions reported in 2007 and one in 2008, generating conversion rates of 0.20% and 0.17% respectively.

Data Table

YEAR 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
TST Converters 4 3 3 3 7 7 8 10 2 1
Conversion Rate 0.29% 0.23% 0.21% 0.28% 0.46% 0.69% 0.82% 0.66% 0.20% 0.17%

figure 6.1

Source: Web-IDSS Enhanced Surveillance Data, CSC 2011

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 1998-2008.  Among males, the proportion having LTBI was 5.9% in 2007 and 7.6% in 2008.  Among females, the proportion having LTBI was 6.0% in both 2007 and 2008. 

Figure 6.2 Latent TB Infection by Gender, Staff, 1998 - 2008

Description of Figure 6.2:

Source: Web-IDSS Enhanced Surveillance Data, CSC 2011

Summary: Figure 6.2 shows the gender-specific proportions of latent TB infections (LTBI) among CSC staff for each year between 1998 and 2008. Overall, the proportion of staff with LTBI decreased over time, from 12.9% in 1998 to 7.0% in 2008. In most years, male and female LTBI rates were similar. Among males, the proportion having LTBI was 5.9% in 2007 and 7.6% in 2008. Among females, the proportion having LTBI was 6.0% in both 2007 and 2008.

Data Table

  1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
FEMALE 10.6% 8.4% 8.9% 6.4% 8.5% 7.3% 5.5% 6.9% 6.4% 5.9% 7.6%
MALE 9.7% 8.7% 12.1% 6.6% 8.1% 5.9% 6.4% 6.3% 6.5% 6.0% 6.0%
TOTAL 12.9% 11.0% 11.6% 7.5% 9.3% 7.1% 5.9% 6.6% 6.6% 6.0% 7.0%

figure 6.2

Source: Web-IDSS Enhanced Surveillance Data, CSC 2011

Part 3: Discussion

Summary of Diseases / Pathogens

Data on infectious disease testing was presented for HIV, HCV, and tuberculosis.  In 2007 the testing uptake for HIV and HCV on admission was almost 50%, which rose to about 58% in 2008.  For general population inmates the testing uptake for HIV and HCV was between 20-25%.  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.  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 guidelinesFootnote 5.  Almost 80% of inmates and about 10% of staff were screened for tuberculosis in 2007-8.  The participation rate for staff may be underestimated since a TB test done by their personal physician would not be reflected in the data.  Further, staff members working at regional or national headquarter offices 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 populationFootnote 6.  At CSC, hepatitis C presents the highest disease burden, with about 30% of the total inmate population infected.  Overall HIV prevalence is around 1.7-1.8% and HAV/HBV/STI prevalence is one percent or less 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 2000-2008; 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 1-1.5% of inmates and less than 1% of 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 55-65%.  While a treatment uptake of 100% may seem optimal, there may be a number of reasons (e.g., not clinically eligible, deferral of treatment, discontinuation due to side-effects or drug resistance) for an inmate NOT being on treatment in any given month.Footnote 7  In 2007-8 about 170 inmates were on HCV treatment and 140 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).

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.  The reports containing Web-IDSS data examine case reports in more detail, and over time, will 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.  Web-IDSS results for bloodborne and sexually transmitted infections were presented for the first time in the report “Infectious Disease Surveillance in Canadian Federal Penitentiaries 2005-2006” and are similarly being prepared for the full surveillance report on infectious disease in federal penitentiaries for 2007-2008.

Footnotes

Footnote 1

As legislated through the Corrections and Conditional Release Act, S. C. 1992, c.20: http://laws.justice.gc.ca/PDF/Statute/C/C-44.6.pdf.

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Footnote 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.

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Footnote 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.

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Footnote 4

Correctional Services Canada (2008); Infectious Disease Surveillance in Canadian Federal Penitentiaries 2002-2004. CSC, Ottawa, 2008

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Footnote 5

For national guidelines for HIV and HCV visit the guidelines page on the PHAC website: http://www.phac-aspc.gc.ca/dpg-eng.php.

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Footnote 6

Prevalence data on reportable diseases in Canada are reported by PHAC: http://www.phac-aspc.gc.ca/.

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Footnote 7

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/research/005008-0211-eng.shtml.

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