3The Regional Municipality of Peel
History of Tuberculosis
Tuberculosis (TB) has had a long and important role in human history.
Over the years, it has gone by many names, including “consumption”,
“white plague” and “phthisis”.1 Evidence from ancient Egyptian mummies
suggests TB has been with us for more than 4,000 years.1 In ancient Greece,
Hippocrates wrote of a common and deadly illness he called phthisis.1 In
Europe in the late 17th-century, one in every four deaths was attributable to
TB.1 During the first half of the 20th-century, TB remained the number one
killer of Canadians. Until the advent of modern antibiotics, TB was usually
treated in special isolation hospitals called sanitaria. In 1953, Canada reached
a peak of 19,000 sanitarium beds dedicated to the treatment of TB patients.
On average, TB patients stayed in sanitaria for just over one year, but many
stayed at the “san” for three to five years.1
Today, modern antibiotics are highly effective against tuberculosis (TB).
Most TB patients can recover at home and return to work within a few
weeks of onset. Most people do not require a hospital stay. In addition, the
usual duration of therapy has shortened to between six and nine months. As
a result of these and other developments, infectious diseases (of which TB is
only a small part) now account for less than 1% of all deaths in Canada.
Canada currently has one of the lowest incidences of TB in the world.
Tuberculosis
HIGHLIGHTS
• In 1998, the age-standardized incidence of tuberculosis (TB) per 100,000 population was higher in Peel (9.6) than Ontario (6.5) and Canada (5.9).
• In Peel between 1982 and 2001, the number of cases of TB almost doubled (48 to 90 cases), largely due to population growth.
• In Peel from 1992 to 2001, the highest incidence of TB was found in those over 60 years of age. The incidence of TB in men and women in Peel was similar over this same period.
• In Peel from 1992 to 2001, most cases of TB were in foreign-born individuals (range 89 to 97%). The majority of these cases were from three TB-endemic countries: India (31%), the Philippines (14%) and Vietnam (13%).
• The lungs were the predominant site affected by TB in individuals in both Peel and Ontario.
• In Peel from 1992 to 2001, 10% of TB cases were resistant to drugs.
—73% were resistant to isoniazid alone or in combination with another drug— 7% were multi-drug resistant (resistant to at least isoniazid and rifampin)
• The proportion of drug resistant TB cases in Peel was higher among foreign-born individuals than in those born in Canada.
4 Communicable Disease Report—2002
Unfortunately, the situation is not the same in other parts of the world.
One-third of the world’s population is infected with tuberculosis (TB).
Although effective treatment and prevention strategies exist, TB still kills two
to three million people every year (one death every 12 to 15 seconds), more
than either AIDS or malaria.
Biology of Tuberculosis
Tuberculosis (TB) is a disease caused by a bacterium called Mycobacterium
tuberculosis. TB mainly affects the lungs but can affect any other parts of
the body.2
Tuberculosis (TB) organisms are released into the air when someone with
infectious, active TB in their lungs or larynx coughs. TB spreads when these
organisms are inhaled. TB found in other parts of the body cannot be spread
to other people.
Frequent, repeated exposure to an infectious individual is usually required
before someone becomes infected with tuberculosis (TB). It is estimated
that exposure for several hours a day for a few months is necessary for an
average, healthy adult to acquire the infection. In some special circumstances,
the infection may be transmitted more readily.3
The vast majority of people with tuberculosis (TB) bacteria in their bodies
do not have an active infection—they remain well and cannot spread the
infection to others. The lifetime risk of inactive infection progressing to
active disease is 10%.3 Active disease occurs when the bacteria spread and
cause damage to the lungs and other parts of the body. Nearly all of the
statistics in this section refer to people with active TB.
High-risk groups for tuberculosis (TB) infection include all individuals who
have spent extended periods of time in parts of the world where the disease
is prevalent, Aboriginal people, people with HIV/AIDS, seniors and homeless,
urban-core residents.4 People living in overcrowded and sub-standard living
conditions are also at greater risk of developing a TB infection.4
People working in health care institutions, social service organizations and
correctional facilities may have frequent contact with high-risk individuals.
Effective occupational health programs can prevent the development of
tuberculosis in any exposed worker.4
Most people do not have frequent contact with, or are not among, the
high-risk groups listed and therefore are unlikely to become infected with
tuberculosis (TB).3
5The Regional Municipality of Peel
Incidence of Tuberculosis in Canada and Ontario
In 1998, Canada had one of the lowest active tuberculosis (TB) disease rates
in the world (about 5.9 cases per 100,000 population).5 Comparable figures
for Ontario and Peel for the same year were 6.5 and 9.6 cases per 100,000,
respectively.
In Canada in 1997, there were seven cases of tuberculosis (TB) per 100,000.6
This incidence was similar to the United States (seven cases per 100,000)6
and Australia (eight cases per 100,000)5, but significantly lower than TB-
endemic countries such as the Philippines (314 cases per 100,000),7 Vietnam
(189 cases per 100,000)7, India (187 cases per 100,000)7 and Pakistan (181
cases per 100,000).7
The number of tuberculosis (TB) cases reported in Ontario and Canada
has declined significantly since the Second World War.3,4 The sharp drop
between 1946 and 1947 was due to the introduction of the first antibiotics
effective against TB. In Ontario, the total number of TB cases peaked in
1943 (2,789 cases) (see Figure 1.1). By 1988, the number of cases declined to
a low of 644 cases. Since then, rates of TB in Ontario have stabilized, with an
average of about 790 cases each year. In 1999, 700 cases of TB were reported,
down from 779 cases in 1997.
Figure 1.1: Number of Reported Active Tuberculosis Cases by Year, Ontario, 1920–1999
Sources: Ontario data 1920–1990 from Public Health Branch, Ontario Ministry of Health and Long-Term Care. Ontario data 1991–1999 from RDIS, Ontario Ministry of Health and Long-Term Care, as of 07/17/2001.
0
500
1,000
1,500
2,000
2,500
3,000
1920
1926
1932
1938
1944
1950
1956
1962
1968
1974
1980
1986
1992
1998
Number of cases
Year
In Peel between 1992 and 2001, the incidence of tuberculosis (TB) fluctuated
between 7.5 and 13.3 cases per 100,000 population (see Figure 1.3 on the
following page). The incidence of TB in Ontario was generally lower than that
in Peel and has demonstrated a gradual decline since 1994 (see Figure 1.3 on
the following page).
6 Communicable Disease Report—2002
Active Tuberculosis in Peel
Peel tuberculosis (TB) data are available for the last twenty years. Like
Ontario, the incidence of TB in Peel declined in the early 1980s, reaching a
low of five cases per 100,000 population in 1986 (see Figure 1.2). Incidence
increased from 1986 to 1990 and has since stabilized to between six and
11 cases per 100,000. The total number of cases of TB in Peel more than
doubled from 1982 to 2001 (48 to 90 cases), but this is largely due to
population growth.
Figure 1.2: Incidence of Active Tuberculosis by Year, Region of Peel, 1982–2001
*Crude rates per 100,000.
Sources: Peel data 1982–1989 from Public Health Branch, Ontario Ministry of Health and Long-Term Care. Peel data 1990–2001 from RDIS, Region of Peel Health Department, as of 07/22/2002. Statistics Canada, Population Estimates and Projections distributed by the Ontario Ministry of Health and Long-Term Care.
TB Rate
TB Cases
0
120
0
12
10
8
6
4
2
100
80
60
40
20
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
Number of cases Cases per 100,000*
Year
7The Regional Municipality of Peel
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001
11.6 11.3 13.3 8.2 10.3 10.8 9.6 7.5 11.3 9.6
0
15
12
9
6
3
7.8 7.5 8.0 7.3 7.1 6.9 6.5 6.1 NA NA
81 81 94 65 84 89 78 67 103 90
Peel
Ontario
Peel Cases
Cases per 100,000
Figure 1.3: Incidence of Active Tuberculosis by Year, Region of Peel and Ontario, 1992–2001
NA: 2000 and 2001 Ontario data not available.
Note: Rates age-standardized using 1991 (adjusted) Canadian population. Sources: Ontario data from RDIS, Ontario Ministry of Health and Long-Term Care, as of 07/17/2001.
Peel data from RDIS, Region of Peel Health Department, as of 07/22/2002.
Statistics Canada, Population Estimates and Projections distributed by the Ontario Ministry of Health and Long-Term Care.
Year
In Ontario in 2001, Peel was second only to Toronto for the number of
tuberculosis cases (see Figure 1.4).8
Figure 1.4: Active Tuberculosis Cases by Health Unit in Ontario, 2001
Sources: Peel data from RDIS, Region of Peel Health Department as of 07/22/2002.
Waterloo data from RDIS, Region of Waterloo Public Health as of 09/01/2002.
York Region data from RDIS, York Region Health Services Department as of 09/12/2002.
City of Hamilton data from RDIS, City of Hamilton Social and Public Health Services Department as of 09/16/2002.
City of Ottawa data from RDIS, City of Ottawa Public Health.
Toronto data from RDIS, Toronto Public Health, Communicable Disease Control Service as of 09/2002.
Number of Cases
Health unit
50 100 150 200 250 300 3500 400
Toronto
Peel
Ottawa
York Region
Hamilton
Waterloo
358358
9090
4646
3737
99
2121
8 Communicable Disease Report—2002
Between 1980 and 1988, reported tuberculosis (TB) cases in Peel accounted for
about 6% of all TB cases in Ontario. Between 1992 and 1999, Peel accounted
for about 10% of Ontario’s TB cases.
From 1995 to 2000, Peel’s hospitalization rates for tuberculosis (TB) ranged
between three to five cases per 100,000. Twenty nine Peel residents died from
TB from 1990 to 1999; however, deaths due to the disease remain relatively rare.
Active Tuberculosis by Age and Sex
The incidence of tuberculosis (TB) varies with age, typically peaking among
those aged 60 years and older with a smaller peak among those aged 20 to 39
years (see Figure 1.5). Age-specific incidence was similar for all age groups in
Peel and Ontario, except for those aged 60 years and older. The incidence for
those 60 years and older was almost twice as high in Peel as in Ontario.
Sources: Ontario data from RDIS, Ontario Ministry of Health and Long-Term Care, as of 07/17/2001. Peel data from RDIS, Region of Peel Health Department, as of 07/22/2002.
Statistics Canada, Population Estimates and Projections distributed by the Ontario Ministry of Health and Long-Term Care.
Peel
Ontario
0–4 5–9 10–14 15–19 20–29 30–39 40–49 50–59 60+0
35
30
25
20
15
10
52.02.0 1.91.9
0.60.6 1.21.2 1.11.1 1.81.8
6.26.24.84.8
11.311.39.39.3
10.210.28.48.4 8.18.1
6.16.1
9.19.1
6.96.9
24.524.5
12.812.8
Figure 1.5: Incidence of Active Tuberculosis by Age Group, Region of Peel, 1992–2001 Combined, and Ontario, 1992–1999 Combined
Average annual cases per 100,000
Age Group (Years)
9The Regional Municipality of Peel
Active Tuberculosis by Country of Birth
Immigrants to Canada from countries with higher tuberculosis (TB) rates
(TB-endemic countries) face a greater likelihood of developing active TB
during their first five years in Canada than Canadian-born individuals.3,4
In Peel from 1992 to 2001, the proportion of tuberculosis (TB) cases among
foreign-born individuals increased from 89% to 97%. The proportion of
foreign-born TB cases in Peel was higher than Ontario for every year from
1992 to 1999 (see Figure 1.7 on the following page).
The higher proportion of foreign-born cases in Peel may be due to the higher
proportion of immigrants in Peel compared to Ontario (40% and 26%,
respectively [1996 Census]) and the higher proportion of recent immigrants
in Peel from TB-endemic countries. In 1996, Peel had a larger proportion of
its population (9%) who had immigrated to Canada in the previous five
years than Ontario (5%).
In Peel, the incidence of tuberculosis (TB) for males and females was similar
among all age groups except those 60 years and older (see Figure 1.6).
Although not shown, the average annual crude rate of TB in Peel was 9.4
per 100,000 for males and 9.0 per 100,000 for females.
0–4 5–9 10–14 15–19 20–29 30–39 40–49 50–59 60 up0
35
30
25
20
15
10
52.72.7
1.41.40.30.3 0.90.9 0.30.3
1.81.8
6.86.85.55.5
12.112.110.510.5 9.99.9 10.610.6
7.57.58.88.8
10.110.18.18.1
20.620.6
29.229.2
Figure 1.6: Incidence of Active Tuberculosis by Age Group and Sex, Region of Peel, 1992–2001 Combined
Sources: Peel data from RDIS, Region of Peel Health Department, as of 07/22/2002.
Statistics Canada, Population Estimates and Projections distributed by the Ontario Ministry of Health and Long-Term Care.
Average annual cases per 100,000
Age Group (Years)
Female
Male
10 Communicable Disease Report—2002
Peel
Ontario
NA: 2000 and 2001 Ontario data not available.
Sources: Ontario data from RDIS, Ontario Ministry of Health and Long-Term Care, as of 07/17/2001. Peel data from RDIS, Region of Peel Health Department, as of 07/22/2002.
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001
89% 89% 91% 89% 94% 94% 94% 93% 96% 97%
0
100
80
60
40
20
75% 78% 81% 81% 85% 83% 82% 84% NA NA
Per cent of foreign-born cases
Figure 1.7: Proportion of Active Tuberculosis Cases Born Outside Canada, Region of Peel and Ontario, 1992–2001
Year
Figure 1.8: Proportion of Active Tuberculosis Cases by Country of Birth, Region of Peel, 1992–2001 Combined, and Ontario, 1992–1999 Combined
Per Cent of Active Tuberculosis Cases
Country of birth
5 10 15 20 25 30 350
India 9%9%31%31%
Philippines 8%8%14%14%
Vietnam 10%10%13%13%
Canada 17%17%7%7%
Pakistan 2%2%5%5%
Hong Kong 5%5%4%4%
China(other than
Hong Kong)
8%8%3%3%Sources: Ontario data from RDIS, Ontario
Ministry of Health and Long-Term Care, as of 07/17/2002.
Peel data from RDIS, Region of Peel Health Department, as of 07/22/2002.
Peel
Ontario
11The Regional Municipality of Peel
In Peel between 1992 and 2001, the most common countries of birth
among tuberculosis (TB) cases included India (31%), the Philippines (14%),
Vietnam (13%) and Canada (7%) (see Figure 1.8 on the previous page). The
percentage of TB cases in individuals born in India was significantly higher
in Peel between 1992 and 2001(31%) than in Ontario between 1992 and
1999 (9%), while the percentage of Canadian-born cases was significantly
higher for Ontario (17%) compared to Peel (7%) (see Figure 1.8 on the
previous page).
Citizenship and Immigration Canada (CIC) screens immigrants for
tuberculosis (TB) and permits those with evidence of inactive, pulmonary
TB to enter Canada on the condition they report to health authorities within
30 days.9 The annual number of immigrant notifications for TB follow-up
received by the Region of Peel Health Department are presented in Figure
1.9. The annual number of notifications has fluctuated from year to year,
although the number has steadily increased from 1998 to 2001. The sudden
increase from 2000 to 2001 can be partly explained by improved reporting.
19920
1,200
1,000
800
600
400
200
Figure 1.9: Immigration Notifications for Inactive Tuberculosis Follow-up, Region of Peel, 1992–2001
Source: Peel Data from RDIS, Region of Peel Health Department as of 07/22/2002.
Number of notifications
Year
336336
1993
361361
1994
526526
1995
816816
1996
730730
1997
582582
1998
309309
1999
382382
2000
492492
2001
1,0181,018
12 Communicable Disease Report—2002
Risk Factors and Risk Settings for ActiveTuberculosis
A “risk factor” is the most likely explanation for a particular person’s
progression from inactive to active tuberculosis (TB). “Risk setting” refers to
the location where transmission most likely occurred. Figures 1.10 and 1.11
present the risk factors and risk settings for TB cases in Peel. “Unknown risk
factor” was reported for 65% of all TB cases in Peel. The three most reported
known risk factors were having previous, inactive disease (12%) or an
underlying medical condition (11%), and being in close contact with an
individual with active TB (11%) (see Figure 1.10).
Per cent based on 832 tuberculosis cases. A case could be reported with more than one risk factor.
Source: RDIS, Region of Peel Health Department as of 07/22/2002.
Figure 1.10: Risk Factors Reported for Active Tuberculosis Cases, Region of Peel, 1992–2001 Combined
Per Cent of Cases
Risk factor
10 20 30 40 50 60 700
Unknown
Inactive Disease
UnderlyingMedical Condition
Close Contact
Other
HIV/AIDS
6565
1212
1111
1111
22
22
In Peel from 1992 to 2001, travel to or living in a tuberculosis-endemic
country was the most often reported risk setting (79%) reported by individuals
with TB (see Figure 1.11 on the following page). Very few cases of TB arose as
a result of exposure at work or school.
13The Regional Municipality of Peel
Anatomic Site of Active Tuberculosis
Most people with active tuberculosis (TB) develop the disease in their lungs
(pulmonary TB). People with non-pulmonary TB can develop the disease in
their brain, kidneys, skin, bones, joints or lymph nodes. Non-pulmonary TB
is more common in areas of the world where TB is prevalent.3
The lungs were the most commonly reported anatomic site of tuberculosis
(TB) infections, followed by the lymph nodes, in cases in both Peel and
Ontario. In Peel for the years 1992 to 2001, 51% of reported infection sites
were pulmonary (see Figure 1.12 on the following page). In Ontario in 1998,
61.4% of TB cases were reported as pulmonary.8
In Peel, non-pulmonary tuberculosis (TB) was reported more frequently in
foreign-born individuals than in Canadian-born individuals (see Figure 1.13
on the following page).
Figure 1.11: Risk Settings Reported for Active Tuberculosis Cases, Region of Peel, 1992–2001 Combined
Per cent based on 832 tuberculosis cases.
Source: RDIS, Region of Peel Health Department, as of 07/22/2002.
Per Cent of Cases
Risk settings
10 20 30 40 50 60 70 80 900
Travel/EndemicCountry
Home
7979
1111
Unknown 44
School 22
Hospital 11
Workplace 11
CorrectionalFacility 11
14 Communicable Disease Report—2002
Based on 888 sites reported by 832 tuberculosis cases in Peel from 1992 to 2001.
Source: RDIS, Region of Peel Health Department, as of 07/22/2002.
Figure 1.12: Active Tuberculosis Cases by Anatomic Site, Region of Peel, 1992–2001 Combined
Pulmonary 51%Pulmonary 51%
Central Nervous System 2%Central Nervous System 2%
Miliary 2%Miliary 2%
Abdominal 2%Abdominal 2%
Other 3%Other 3%
Bone and Joint 4%Bone and Joint 4%
Genitourinary 5%Genitourinary 5%
Pleura 8%Pleura 8%Lymph Node 23%Lymph Node 23%
Figure 1.13: Active Tuberculosis Cases by Anatomic Site and Place of Birth, Region of Peel, 1992–2001 Combined
Per Cent of Cases by Site
Site of tuberculosis
10 20 30 40 50 60 70 80 900
Pulmonary 53538080
55
55
55
33
22
22
22
Lymph Node 2626
CentralNervous System
22
Pleura 99
Genitourinary 55
Bone and Joint 55
Miliary 22
Other
Based on 60 Canadian-born and 772 foreign-born tuberculosis cases. Some cases may have reported more than one site.
Source: RDIS, Region of Peel Health Department, as of 07/22/2002.
Foreign-born
Canadian-born
66
15The Regional Municipality of Peel
Drug-Resistant Tuberculosis
Drug resistance arises when medication is improperly prescribed or taken.3
A tuberculosis (TB) case is defined as being drug-resistant if the strain of
TB causing the disease is resistant to one or more of the five first-line
drugs: isoniazid, rifampin, pyrazinamide, ethambutol and streptomycin.10
Resistance prolongs treatment by at least three months. Resistance to at least
isoniazid and rifampin—the two best TB drugs—is called multi-drug resistant
tuberculosis (MDR-TB). MDR-TB is treated using second-line drugs (drugs
other than the five, first-line drugs mentioned above). Second-line drugs are
more expensive, less effective and have many more side effects than first-line
drugs. As a result, treatment of MDR-TB continues for at least two years
and must be closely monitored.
In Peel from 1992 to 2001, a total of 85 tuberculosis (TB) cases were resistant
to one or more drugs. Drug resistance as a proportion of total TB cases
fluctuated widely from year to year (see Figure 1.14).
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001
2% 15% 10% 18% 11% 7% 10% 19% 3% 12%
0
25
20
15
10
5
7% 8% 10% 9% 9% 11% 9% 13% NA NA
Peel
Ontario
Per cent of total tuberculosis cases*
Figure 1.14: Proportion of Drug-Resistant Tuberculosis by Year, Region of Peel and Ontario, 1992–2001
NA: 2000 and 2001 data not available.
* Per cent based on total tuberculosis cases for each year in Peel and Ontario.
Sources: Ontario data from RDIS, Ontario Ministry of Health and Long-Term Care, as of 07/17/2001.
Peel data from RDIS, Region of Peel Health Department, as of 07/22/2002.
Year
16 Communicable Disease Report—2002
In Peel from 1992 to 2001, 74% of all tuberculosis (TB) cases reported
drug sensitivity patterns. Twenty-six per cent of TB cases were classified
as “unspecified” (see Figure 1.15). Unspecified cases are those for which TB
specimens could not be cultured to obtain information on drug resistance.
Ten per cent of total TB cases in Peel were classified as drug-resistant.
Resistance to isoniazid, one of the two best anti-TB drugs, occurred in 73% of
Peel’s resistant cases. Resistance in these cases occurred with isoniazid alone
or in combination with resistance to another drug. Multi-drug resistant TB is
especially troublesome and occurred in 7% of all drug-resistant cases in Peel.
Figure 1.15: Drug-Resistant Tuberculosis Cases, Region of Peel, 1992–2001 Combined
Based on 832 tuberculosis cases.
Source: RDIS, Region of Peel Health Department, as of 07/22/2002.
Sensitive (64%)Sensitive (64%) Streptomycin (SM) (14%)
Streptomycin (SM) (14%)
INH + SM (15%)INH + SM (15%)
Multi-drugresistant (7%)
Multi-drugresistant (7%)
INH + SM + other (6%)INH + SM
+ other (6%)
INH + other (6%)
INH + other (6%)
Pyrazinamide (6%)
Pyrazinamide (6%)
Isoniazid (INH) (46%)Isoniazid (INH) (46%)
Unspecified (26%)Unspecified (26%)
Resistant to drugs (10%)Resistant to drugs (10%)
Multiple drug-resistant tuberculosis (MDR-TB) is the result of poor
treatment of active TB. Physicians’ inadequate prescribing of antibiotics
and patients’ non-compliance with treatment all contribute to MDR-TB.11
In addition, the speed of air travel has increased the movement of people
around the world and the possibility of importing drug-resistant TB into
Canada.11 Various studies have noted that foreign birth is a significant factor
associated with drug resistance.11
Poor compliance with anti-tuberculous therapy is the most common reason
for treatment failure. Directly Observed Therapy (DOT), in which a trained
individual observes the tuberculosis (TB) patient swallow each dose of
medication, is an effective way to monitor adherence with therapy.12 TB drug
regimes using DOT have been shown to significantly reduce the rate of drug
resistance and the rate of relapse when compared to self-administered therapy.12
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