 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
| |
|
||||||||||||||||
| |
|
||||||||||||||||
|
TUBERCULOSIS PREVENTION AND CONTROLSection II. Presentations
TB is a global emergency. First, TB is a very large problem. Data from World Bank estimates reveal that, when compared to other infectious diseases, TB kills more adults than any other single infectious agent. The situation is worsening. Secondly, TB prevention and control interventions are among the most cost-effective public health measures. Yet, despite the magnitude of the problem and despite very cost-effective intervention measures, TB has been ignored for the last twenty years or so, particularly between 1970 and 1990. The TB prevention and control program at World Health Organization (WHO) received only $16 million for the year 1990 which is much less than other control programs. The recent trend in TB is worsening. TB incidence increased tremendously in the mid-1980s. In some countries, such as Zambia, TB incidence tripled during this period. In Tanzania and Ivory Coast, there is an increase of 72 and 40 per cent, respectively, between the mid-80s and 1990s. In Asia, TB is a huge problem. In Eastern Europe and the former Union of Soviet Socialist Republics (USSR) during the late 1980s, the incidence and prevalence have increased, mainly due to the disintegration of the political system, exposing poor control programs and weakened surveillance systems. Anti-TB drugs are no longer readily available because of the creation of new countries, very high trade barriers, and lack of foreign currencies. Simply put, some of the drugs are not available in some of the countries. In Western Europe, there are new increases in TB. In countries such as Switzerland and the Netherlands, one of the main factors contributing to this increase is TB among the foreign immigrants and laborers. In the United States, in 1986, the government, particularly the Centers for Disease Control (CDC), requested new funding (approximately $35 million) to reinvest in TB prevention and control. The request for the funds was unsuccessful and the TB situation deteriorated. The CDC budget for TB has been increased to about $120 to $130 million in 1993 to cope with the resurgence of the disease. The question is: if CDC had received $35 million in the late 80s, would the United States have to spend such a large amount now, just to try to cope with the increased case load? The message is clear. If governments do not invest now in TB prevention, the TB situation will deteriorate and more money will be required in the future. If the current global situation continues, TB might kill approximately 40 million people during the last decade of this century. Developing countries account for more than 95% of TB deaths, and the majority of the deaths will occur in South-East Asia, East Asia Pacific, and Sub-Saharan Africa. Additional TB deaths will occur in East European countries. There are three reasons why the current situation has developed. One of these is related to changes in population structures. In terms of population, there are two things happening in the world, particularly in developing countries: total population is increasing very rapidly; and the number of young adults is increasing much faster than other parts of the population. The second reason is related to social unrest, such as large-scale movements of populations, particularly during wars or disasters, whether on a global- or a mini-scale. Population movement leads to population crowding and increased transmission of TB. At the same time that TB transmission is going to increase, HIV epidemics are spreading, resulting in more persons with compromised immune systems. Thirdly, countries are paying the price for their past neglect of TB-control programs. TB has been neglected over the past 20 to 25 years. A very small amount of money was spent for TB control. Furthermore and unfortunately, this small amount of money was spent unwisely in many parts of the world. The end result has been the resurgence in TB. For example, in three different parts of the world, Tanzania, Nicaragua and Algeria, the largest proportion of the TB cases occur in the 15- to 54-year-old age grouping. This young- adult age group is growing tremendously quickly compared to other age groups. Because of this change in the demographic structure, the number of TB cases is going to increase. HIV is a factor leading to increases in TB, because HIV and TB infection are common occurrences with an estimated five million people co-infected. The majority of them are in Sub- Saharan Africa, although the spread of HIV is increasing much faster in Asia than in Africa. Estimates of the increase assume that both TB infection and HIV infection are completely independent. In many parts of the world, this may not be the case. HIV is among the highest risk factors for TB. Unless HIV prevention coincides with TB prevention to reduce their negative impact, TB is going to increase. WHO estimates that about 4% of the new TB cases are due to HIV infection. This proportion is going to increase to about 14% by the year 2000. WHO further estimates that current global demographic trends account for 75% of the current increase in TB cases, while 25% is contributed by HIV. With respect to the small amount of money spent on TB, with no intervention at all for this chronic infection, about 50% of those infected with TB will die within five years. With a national TB-control program, this natural history can be changed dramatically. In China, with international financial assistance, 92% of TB cases are being cured. The proportion of those dying during treatment is only 2% to 3%. The proportion of those whose TB remains chronically active, representing a failure of the program, is about 3%. About 5% or 6% of the cases are lost during follow-up. Good programs, therefore, can reduce chronic and failure cases of TB. Minimizing the chronic cases minimizes TB transmission and the development of drug resistance. With very poor TB-control programs, only about 40% of TB cases are cured. Cases lost to follow-up or treatment failure rise to about 30% to 40%. A poor TB-control program will create many chronic cases that are often drug resistant. The occurrence of MDR-TB outbreaks in New York City illustrates the point. In New York, TB was increasing steadily since the mid-70s and then the HIV epidemics occurred, with a subsequent tremendous increase in TB cases. There are three important points with regards to TB-control programs. One, if a national program is undertaken, it must be implemented rigorously, otherwise, the program itself might create a worse situation than no intervention at all. Two, it is important to monitor the effectiveness of the treatment intervention. Three, effective global strategies are required. In 1991, global targets for TB were set. Of these, there are two main targets. The first goal is to achieve at least an 85% cure rate for all current and new cases. To achieve this goal, the quality of care among detected cases must be guaranteed before new cases are actively sought. Once a high quality of TB treatment is achieved, the next goal is to actively find 70% of the existing cases. Securing quality treatment in the public health structure is a major consequence of this strategy. What are the key ingredients to achieve this target? There are several components, one of them being government commitment concerning TB. Another involves a standardized global approach for both case-finding and treatment. In many countries, for example, countries in Europe, the case definition of TB is not standardized, making it very difficult to compare statistics for case notification. Without standardization of treatment, it is almost impossible secure quality, (e.g., in Bombay, India, in private practice, there are 78 different regimens used for the treatment of TB). A third component is a secure drug supply. Without a regular drug supply, there is no rationale for implementing a TB-control program. A lack of drugs jeopardizes the credibility of the program. Drug supply and logistics are crucial issues, but they are often ignored or misunderstood by many TB workers. Finally, an adequate surveillance system is needed, including monitoring of program performance. To measure treatment outcome, crucial indicators are needed to indicate the quality of the treatment program. Disease surveillance measures how many cases are being found, their trends, and their epidemiological characteristics. To monitor whether a country is making progress in TB control, three different indicators are used. First, as a measure of governement commitment, both financial as well as technical, the government should have a good TB-control manual that includes the key components mentioned above. Second, indicators of the extent of implementation of the guidelines in the manual should be monitored. Third, the outcomes of the interventions (e.g., how many cases are found, how many are actually cured, how many become failures, how many die, how many drop out, etc.) must be measured. These three different classes of indicator can be used to monitor the progress of TB-control programs. The principles apply to both developing and industrial countries, including Canada. What are the major TB problems in the industrial countries such as Canada? (1) Many TB cases are found among the elderly. (2) As revealed from data from the Netherlands, the majority of TB cases occur among foreign-born persons. Among native-born Dutch, for example, TB cases continue to decrease; however, cases of TB among foreign-born persons are increasing, reaching more than 50% of reported cases. Given the increased movement of the world's population, this phenomenon is going to continue in industrial countries. (3) In many industrial countries TB occurs in special pockets of the popualtion. In the Bronx, New York, there was a large increase in TB cases from 1980 to 1988 because of an inadequate TB-control program coupled with poor living conditions. (4) In some European countries, notification of TB actually occurs after the patient has died. In Norway, 23% of the reported cases are found by post-mortem examination. Such information indicates that physicians are missing the diagnosis of TB with some frequency. At the first meeting of the countries in WHO's European Region in 1992, it was agreed that government responsibility and commitment was essential for a good TB-control program. The national government has to assure that new cases are identified early and that older cases are cured. National governments must establish good surveillance systems based on standardized definitions. In addition, monitoring the outcome of treatment is essential. Finally, the importance of maintaining a cadre of well-trained specialists in TB is essential. In summary, TB is a huge problem and this problem is getting worse. If governements do not act now, the TB burden and its costs will become tremendously high over the next ten years. Because of the increasing global movement of populations, TB will not respect national borders. TB cannot be controlled in Canada and other industrialized countries without good TB-control programs in developing countries. Canada has the potential to contribute to the global fight against TB, and this potential has to be tapped. By mounting a good TB-control program, Canada can maintain a good personnel basis consisting of experts who are able to contribute to the implementation of national TB-control programs in developing countries. The lack of expertise at the global level is one of the biggest constraints faced by WHO. WHO can mobilize only a dozen TB experts whose expertise is trustworthy. By demonstrating strong leadership in the control of TB domestically, Canada also can figure as a major player in the fight against TB globally.
There is some evidence that TB existed in South America centuries before the Europeans arrived. There is less evidence that there was TB in North America until it was introduced by explorers and settlers. However, the historical record does show that dozens of Aboriginal people in Canada were dying of the disease at the turn of the century. The British North-America Act (BNA) of 1887 gave the provinces responsibility for health. Section 91, however, assigned to the federal government authority over Indians and land reserved for the Indians. The TB programs for Aboriginals began in earnest with the appointment of Dr. Peter Brice to the position of Chief Medical Officer for the Department of Indian Affairs in 1904. As a result of his recommendations, segregation of TB patients, training of nurses, building of (or provision of) temporary hospitals, and the concept of visiting nurses were implemented. The first departmental hospitals were build in 1917 and the early 1920s. By 1943, there were 14 hospitals for Indians with 540 beds, half of which were occupied by patients with TB. The Department of Indian Affairs became a branch of the Department of Mines and Resources in 1936. Many changes occurred between 1936 and 1945. In 1938, for example, an intensive program to discover and treat active cases of TB was begun. In 1944, an expansion of services was begun and an advisory committee on the prevention and control of TB among Indians was established. When the Department of National Health was created in 1945, it was given responsibility for TB among Indians as well as other health services for Indians in Canada. The Department of National Health Act provided that the duties, powers and functions of the Minister extend to and include all matters related to the promotion and the preservation of the health and social welfare of the people of Canada, over which the Parliament of Canada has jurisdiction. Following this move, the necessary funding and expertise were made available, war-time hospitals were modified and new sanatoria and nursing stations were built. Aggressive case-finding, extensive vaccination, and new treatment regimens were begun. The Medical Services Branch (MSB) came into being in 1962 and the current organization of Indian and Northern Health Services gradually evolved to where it is today. Under the Indian Act of 1874 and later editions, under Section 72, the Governor-in-Council would make recommendations to prevent, litigate, and otherwise control the spread of disease on reserves (whether communicable or not), provide medical and health services for Indians and provide compulsory hospitalization and treatment for those Indians with infectious diseases. The Act and the Regulations enabled authorities (e.g., in Alberta) to sign forms to sign (two) forms, obtain the signature of the Regional Director of Indian Affairs who was officially the Chief Medical Officer, and, take a copy of these to the RCMP who would then go into the reserve communities and more or less arrest TB patients). Such persons were then incarcerated in the TB ward at the hospital in Edmonton and kept there until willing to accept treatment. These Regulations under the Act are no longer in existence, and this practice has been discontinued. "Indian" included the Inuit, although the term was not technically defined until the 1982 Constitution Act to include Indians, Inuit, and the Métis. Although the Constitution established legislative jurisdiction only, the mandate has been generalized to the responsibility for the provision of programs and services. It has been generally accepted that the federal government is responsible for health services for First Nations, although health is within the jurisdiction of the provinces. It is, however, the position of the Government of Canada that this responsibility is confined to treaty Indians living on reserves, and that Indians who live elsewhere in Canada are the responsibility of the provinces. Federal responsibility is based on this special relationship that exists between the Crown and the Aboriginal people of Canada, rather than on law. This relationship is not interpreted to mean that services or programs MUST be provided. The Constitution Act of 1982 affirms and recognizes existing Aboriginal and treaty rights, but again does not define them. Many Indian groups maintain that they are entitled to free, comprehensive health services as a treaty right, the treaties being different from the acts of Parliament and having been concluded by Indian chiefs. In the last century and to this day, the fact that Queen Victoria, through her agent, signed the treaty is interpreted to mean that now the Government of Canada is responsible for holding to the provisions of these treaties. The claim about comprehensive health services is based on the clauses of treaty number six, which was signed in 1876, and verbal agreements which were purportedly made when treaty number eight was negotiated in 1899. The clause stipulates that a medicine chest should be kept at the house of each Indian agent for the use and benefit of the Indians. The final decision on this matter has yet to be made by the Supreme Court. A goal of the MSB is to provide services to First Nations people living on reserves, comparable to those provided to other Canadians living in similar geographic areas. An overview document that details the 1979 Indian health policy gives definitions of various terms for Aboriginal people, summarizes the categories of services provided by MSB, and lists numbers of personnel and facilities throughout the country. The policy rests on three so-called pillars: one, the traditional relationship between the Indian people and the federal government; two, community development to remove the conditions of poverty and apathy that prevent the members of the community from achieving a state of physical, mental and social well-being; and three, the Canadian health system, which comprises many specialized interrelated elements that may be the responsibility of federal, provincial, or municipal governments, Indian lands, or the private sector. The third pillar identifies the need to promote the capacity of Indian communities to play an active, more positive role in the health system and in decisions affecting their health. MSB subscribes informally to the WHO/UNICEF definition of primary health care, and our current transfer initiative has begun the process of transferring all health services to First Nations communities. The current MSB services for registered Indians (treaty Indians) can be put into three categories:
The role of Statistics Canada as it applies to health statistics is contained in Section 3 of the Statistics Act. The Act charges Statistics Canada to collect, compile, analyze, abstract, and publish statistics in relation to the health and social status of Canadians. In relation to TB then, the statutory function of Statistics Canada is to compile and process data from the provinces and territories, and then to publish annual reports and analytical papers on the incidence and epidemiology of TB in Canada. In fact, Statistics Canada has collected and published TB data and has functionally carried out national incidence and mortality data for 70 years. These historical reports show rates for notifiable diseases including TB by province (beginning in 1924), and annual reports on TB alone (beginning in 1937). Of course, a vital component of data processing is the guarantee of confidentiality of any information that relates to individual Canadians. In fact, the viability of Statistics Canada rests on the public confidence in its ability and will to protect the data that are collected and received. The violation, or even the perceived violation, of the security of the data would undermine both public confidence and the continued capability of the agency to collect data. Absolute protection of information is an essential principle underlying all activities undertaken by Statistics Canada. The Statistics Act is quite clear in this regard. It prohibits the disclosure of any information (obtained under the Act) in such a manner that it is possible to relate the particulars obtained from any individual return to any identifiable person, business, or organization. This guarantee of security is offered to any party from whom information is collected. Before describing Statistics Canada's current role in national TB surveillance, some relevant decisions that have been made regarding some of the same questions of concern to this meeting must be reviewed. In fact, the terms of Statistics Canada's current role in TB surveillance as well as LCDC's role were endorsed in a thorough review undertaken in 1989 by the Communicable Disease Subcommittee of the Advisory Committee on Epidemiology. At that time, it was recommended that Statistics Canada resume or actually retain responsibility for the following components of surveillance: form redesign (the notification form), data entry program design, data entry and verification, short-term data storage, long-term storage (historical files and reformatting), annual revision and production of standard tables, and responsibility to respond to data requests. It was recommended that analysis should be performed collaboratively with LCDC. The committee also recommended that LCDC plan its new communicable disease surveillance data base to include TB, and, "when LCDC is capable of performing the full functions presently carried out by Statistics Canada, it should take over TB reporting. The provincial TB directors should be consulted on all steps taken in this regard." The respective roles regarding TB surveillance were discussed again in an Advisory Committee on Epidemiology meeting in 1993. Again, the matter of transfer of responsibility for TB data from Statistics Canada to LCDC was discussed, though no recommendation in this regard was recorded. The transfer of data functions from Statistics Canada could not happen without the unanimous consent of all provinces and territories. In the fiscal and political climate of 1994, the goals of Statistics Canada are to facilitate the collection of information that will be nationally useful in the control of TB, to perform and promote the analysis of TB data, and to disseminate the results of these surveillance activities. Statistics Canada is skilled in processing data that are submitted in a myriad of different formats, maintaining long series of data, and making information available to a variety of users. An example is the statistical chronical of TB in Canada prepared a year or two ago by Anna Branker and her collaborators. In addition to annual reports on TB, the highlights of which are released to the media, Statistics Canada publishes descriptive and analytical articles on TB in Health Reports, which is a quarterly publication indexed in Index Medicus, as well as in other peer-reviewed medical journals. In the past few years, data analysis as opposed to data production has become an increasingly important function in the Health Statistics Division. The respective roles of Statistics Canada and LCDC with regard to data analysis have never been well defined and delineated. The following charts and graphs illustrate work done by Statistics Canada. Figure 1shows cases of TB by income quintile, for persons whose residence is in metropolitan areas. These data are derived from the TB-notification forms. Postal codes were used to assign each case to a census tract, and the data do not include Quebec since postal codes from Quebec are not available. These data also include only about 15% of all cases. Most people included are not residing in metropolitan areas of Canada. The census tracts were assigned to quintiles according to the percentage of individuals in a census track who were in a family whose total family income was below the low income cutoff, and each census track was rated according to the per cent population from the low income cutoff. The census tracts were assigned to five groups of quintiles, from the lowest to the highest per cent of low income. The distribution of TB cases by birth place (Canadian born and persons whose birth places are outside Canada) and income quintiles follow the same trend. The greatest proportion of cases in both groups fall within the poorest income quintiles (Figure 2). The percentage of TB cases that are non-respiratory vary by country of birth as demonstrated by data from reported cases in 1992 (Figure 3).  
Figure 4 shows the incidence of TB, or at least notification rates, in 1982 and 1992 by province. There was actually a decrease between these two points in time in most provinces. Figure 5 shows a substantial decline in incidence that has occurred in the older age group in recent years in Canada. TB rates are conventionally expressed as crude rates per hundred thousand and the fairly stable crude rate since the mid-80s actually masks some of the age-specific decreases.
The problem with crude rates is that substantial growth in the population is occurring in the elderly segment, which also has the highest incidence of disease. The percentage of total cases accounted for by three groups (those born outside Canada, the non-Aboriginal Canadian born, and Aboriginal people) is demonstrated in Figure 6. The proportion accounted for by non-Aboriginals has decreased, the immigrant proportion has increased and there is a fair amount of stability in the proportion accounted for by Aboriginals. Figure 7 shows the rates in two groups: registered Indians and the rest of the population. The male/female differential is not as great among registered Indians as it is in the rest of the population. Figure 8 (pie chart) reveals the percentage of cases of TB in each group that were detected through contact investigation. For Aboriginals, this method was used in 33% of cases that were found; among immigrant cases, it accounted for only 2%.
Regarding respective roles with regard to TB information, the key question is where each function might best be performed. A stable infrastructure is required as well as technical and analytical expertise, and an environment in which the security of the data is protected absolutely in the shelter of an institutional mandate that is relatively impervious to political whim and the appearance and disappearance of so-called "sunsetted" special initiatives. LCDC's role in TB surveillance will implicate Statistics Canada since it is very much involved in national TB surveillance related to case reporting, analysis, and information dissemination. While it is true that Statistics Canada has been discharging these functions since 1937, flexibility is important. Statistics Canada will continue to respond to recommended changes in its role, as long as the recommendations are based on the consensus of the jurisdictions involved. If TB data are to reach their full potential, significant interaction between the producers and the users of the data must occur.
This presentation will describe LCDC's role and the general public health network in Canada to provide the context for defining LCDC's role in TB prevention and control. Two premises define LCDC's role. The first fundamental premise is that governments do have a role in protecting the health of the public. There are two basic tasks for government in protecting the health of the public. One task involves the assessment of the level of health risk. The second task for government in safeguarding the health of the public is the creation of policy that will protect the health of the public through management of the risk. LCDC contributes to the creation of policy by generating and disseminating information, maintaining expertise, making the expertise available, and guaranteeing scientific excellence. LCDC provides funds and resources, creates guidelines that are the tools for risk management and program evaluation, and, finally, develops consensus. A second fundamental premise is that national public health is a federal responsibility. The Canadian public expects the federal government to assume this responsibility. When there is a national emergency such as an outbreak of polio, the public turns to Health Canada for a response. The LCDC mission is to be the national centre for the identification, investigation, control, and prevention of human disease. This mission is perforemd through comprehensive surveillance. Comprehensive surveillance is fundamental to disease prevention and control. Surveillance identifies hazards, defines the natural history of disease, targets opportunities for prevention and control, and is the foundation for sound health policy. Although sound health policy may not always be based on surveillance data, the information generated through surveillance is often the key ingredient. The current philosophy in Health Canada holds that policy formulation should be evidence-based. Decision and policy development should be based on scientific fact. LCDC's mandate is a broad mandate supported by legislation, cabinet directives and a wide range of federal/provincial agreements. LCDC's mandate is derived from the National Health and Welfare Act, which describes the Minister's role. There are eight core functions stemming from this Act. One is the accurate identification of infectious agents in support of patient management. LCDC laboratories receive a large number of specimens from around the country for the diagnosis and management of individual patients. Other functions include the maintenance of quality control programs for the identification of infectious agents; research and development in diagnostic technology for infectious diseases; national and comprehensive disease surveillance; outbreak investigation; international liaison and collaboration; support for disease control efforts; and training. To provide comprehensive surveillance, risk management, disease control, and training in public health, LCDC depends heavily on the Canadian public health network. This network consists of a large number of people and institutions. For national surveillance, this network includes LCDC and the provincial epidemiologists and medical officers of health units. There are about 200 health units in Canada, with a staff of about 5,000 people that contribute information to the entire system. The system of provincial public health laboratories, with approximately 2,000 laboratory scientists and technicians across the country, is a critical component. The network includes university-based health researchers and non- governmental organizations, such as the Canadian Cancer Society, the National Cancer Institute, the Canadian Lung Association, the Allergy and Asthma Information Association, the Canadian Public Health Association, Canadian Heart and Stroke Foundation and many others. Many professional societies, such as the Canadian Public Health Association, the Canadian Medical Association, and the Canadian Infectious Disease Society also are a part of the Canadian public health network. Other government agencies, such as Statistics Canada, are included. LCDC interacts with the network to utilize all of the expertise it has available to solve public health problems. LCDC is located in the Health Protection Branch, one of the major divisions of Health Canada. There are four principal bureaus: the Bureau of Communicable Disease Epidemiology, the Bureau of Chronic Disease Epidemiology, the Bureau of HIV/AIDS Laboratories and Research, and the Bureau of Microbiology. In addition, there is a Director General's Office, that includes a number of staff functions such as Biosafety, Biometrics, Risk Management and Strategic Planning, the Office of Special Health Initiatives, and Administration. For responding to a particular disease problem, such as TB, multiple units in LCDC are usually involved. Different organizational units are responsible for different aspects of TB prevention and control. To provide greater unity, visibility, and coherence to LCDC's efforts in TB, file management is used to permit coordination across the organizational structure of the institution. File management combines the necessary expertise from both epidemiology and laboratory science to work as a team to build a coherent and unified approach to TB prevention and control. The following presentations will review some of the activities of the file and provide a brief chronology of recent activities within the TB file.
I would like to start by acknowledging and thanking Statistics Canada for making the results of their annual analysis available. All numbers used in this summary are from Statistics Canada data unless otherwise acknowledged. WHO has requested that four specific rates be calculated annually for all TB cases reported. Canada currently routinely reports two of these annual rates per 100,000(the total and extrapulmonary TB) and could easily calculate the other two(pulmonary smear positive and smear negative TB). Although Canada reports one of the lowest TB rates in the world, the Canadian TB rate abruptly stopped declining in 1987, ending decades of decrease. This change in trend has caused an intensive re-evaluation of the TB situation in Canada. From 1987 until 1992 (last national figures), the rate has stabilized at 7.2 to 7.4 cases per 100,000 which meant that 1,947 to 2,091 TB cases per year were reported. Statistics show marked geographical differences in the TB rate reported in Canada with the Northwest Territories reporting the highest rate in 1992 (41.8 per 100,000) and Nova Scotia reporting the lowest rate (1.4 per 100,000). Gaudette and Ellis (1993) document striking differences in TB rates within a single province when the rate is determined for electoral districts. The trends of provincial TB rates also differ. Ontario and Alberta have increasing TB rates from 1989 to 1992. Finally, British Columbia is trending upwards while the other provinces and territories report decreasing rates. The number and proportion of TB cases occurring in Canadian risk groups has changed over the past 12 years. In 1980, 1,366 (49.4%) of 2,762 TB cases occurred in non-Aboriginal, non- foreign-born Canadians, 390 (14.1%) cases in Aboriginal Canadians, and 976 (35.5%) cases in the foreign- born. The number of cases occurring in non-Aboriginal, non-foreign-born Canadians has progressively fallen, while the number of cases reported in the other two groups has remained approximately unchanged. In 1992, 530 (25.3%) of 2,091 TB cases occurred in non-Aboriginal, non-foreign-born Canadians, 388 (18.6%) cases in aboriginal Canadians and 1,102 (53%) cases in foreign-born. Over 1.6 million people immigrated to Canada from 1980 to 1992 (personal communication, Dr. B. Gushulak, Immigration Canada). Analysis of the country of birth of immigrants reported to have TB shows a changing pattern consistent with changes in country of birth of immigrants landing in Canada. Fewer TB cases are now being reported in European immigrants and more cases are reported in Asian immigrants. The rate of TB occurring in aboriginal peoples is difficult to calculate because of an ongoing concern that the number of aboriginal people living in Canada may differ from the information reported to Statistics Canada for census purposes. With this limitation in mind, the estimated rate of TB in First Nation peoples is 6 to 10 times higher than the Canadian national rate. Each province reports a different percentage of cases occurring among each of the risk groups. Only in Alberta the distribution in risk groups resembles that of Canada (50% immigrant, 18% First Nation, 32% non-aboriginal, non-foreign born). New Brunswick reports that more than 85% of cases occur in non-Aboriginal, non-foreign born; Saskatchewan reports more than 85% of cases occur in aboriginal peoples; and Ontario reports that more than 85% of cases occur in the foreign-born. From 1980 to 1992, the age-specific TB rate increased in the 0-4 age group (though the highest rate was reached in 1990); remained approximately stable for the age groups between 5 and 34 years; and decreased in the age groups above 34 years of age. From 1990 to 1992, the median age of persons with TB among non-Aboriginal, Canadian-born was 59 years compared to 23 years for Aboriginal Canadians and 37 years for immigrants. Approximately equal rates of TB are reported in males and females less than 25 years of age, though males have a higher rate than females after this age. The national TB rate is 8.3 per 100,000 for males and 6.6 for females. The number of individuals reported in Canada to have AIDS and to have active TB is small. However, the number of reported cases is underestimated for several reasons. Between 1987 and July 1993, the Canadian AIDS surveillance case definition included only individuals with disseminated or extrapulmonary TB. The Canadian AIDS surveillance case definition was expanded in July 1993 to include individuals infected with HIV who developed pulmonary TB as well as disseminated or extrapulmonary TB. Cases of pulmonary TB in HIV-infected individuals would not be reported prior to July 1993 thus leading to an underestimate of co- infected persons. Delays and failures to update case reports also lead to underestimating of co-infection. Opportunistic infections, which develop during the time an individual has AIDS, are reported to the AIDS Case Reporting Surveillance System (ACRSS). However, the reporting of TB and other opportunistic infections is frequently delayed since the update reports are often submitted only when the death of the individual is reported. It is difficult to assess if the case report includes a complete list of all opportunistic infections that developed in each individual. The Division of HIV/AIDS Epidemiology of LCDC reports that as of March 1994, 4.1% of reported Canadian persons with AIDS had a diagnosis of TB (1.1% pulmonary TB and 3% disseminated or extrapulmonary TB). British Columbia reports that 4.3% of their identified AIDS patients have been diagnosed with active TB. The level of co-infection can also be examined from data collected by provincial TB registries (the national TB registry does not ask for HIV status). Ontario reported that 1.5% of reported active TB cases were co-infected with HIV from 1989 to 1992. British Columbia similarly reported that 1.5% of the TB cases reported from 1984 to 1990 were co-infected with HIV. The rate of extrapulmonary disease reported in Canada has remained stable over the last 12 years at 1.7 cases per 100,000. However, the rate of pulmonary cases (ICD-9 codes 011.0 to 011.3 and 011.5 to 011.9) fell from 7.9 cases per 100,000 in 1980 to a low of 3.9 cases per 100,00 in 1990 and has increased to 4.3 cases per 100,000 in 1992. Twenty per cent of all cases reported each year from 1990 to 1992 have no culture information reported and 11.4% of the cases have a negative culture. The Canadian Thoracic Society (1994) stated that approximately 85% of pulmonary cases should have laboratory confirmation. Data from 1990 to 1992 indicate that 63% of pulmonary cases (ICD-9 codes 011.0 to 011.3 and 011.5 to 011.9) had a positive culture. WHO also requests data with respect to case-holding or treatment of TB cases. Canada can provide data with respect to number of deaths attributed to TB but cannot provide national data with respect to cure rate, treatment completion rate, failure rate, defaulter rate, transfer-out rate or record of re- treatment of cases. However, there is a surrogate marker that can be used to estimate the quality of treatment of TB in Canada. Reactive cases occur because therapy was incomplete. From 1981 until 1992 the percentage of reactivated cases in Aboriginal individuals decreased from 20% to 11.4%. Over the same time period, the percent of reactive cases in immigrants increased from 6.8% to 11.8%. An Ontario TB report indicates that the percentage of reactivated cases rose from 11% in 1989 to 16% in 1992 and that the majority of reactivated cases occurred among teh foreign- born. It is not known whether the original treatment of the immigrants occurred in Canada or in another country. However, data from 1990 to 1992 suggest that the original diagnosis and treatment of immigrant cases occurred prior to their arrival in Canada. Canadians are at risk of developing drug resistant TB either because they have been partially compliant with treatment (secondary resistance) or because they have developed active TB after they were exposed to someone with drug resistant TB (primary drug resistance). Compliance with TB therapy is crucial but difficult to achieve since "short" course therapy routinely requires treatment using three or four drugs for at least six months. Data on presence or absence of drug resistance has been collected nationally by Statistics Canada since 1990. However, the quality of the data collected has been questioned by most experts because of reporting irregularities. Therefore, it has been difficult to interpret the reported resistance information. LCDC, Statistics Canada and the provinces will be working together to improve the quality of data routinely reported on a national basis. The results of a special national drug resistance study should be reported in the fall of 1994. The number of reactivated TB cases reported in Canada provide an indirect marker of the potential of secondary drug resistance occurring in Canada. Since secondary drug resistant patterns should conform to the drugs used to treat TB, the level of secondary rifampin resistance in reactivated immigrant cases should be low since many developing countries can not afford to use rifampin in their in treatment regime. Trends in reactivated TB cases reported in Canada has already been discussed. Twenty-six per cent of new TB cases reported in New York City are resistant to one or more drugs and 13.9% are resistant to the two most important drugs used against TB (isoniazid [INH] and rifampin) plus other anti-TB drugs (i.e., the definition used in this article for MDR TB). Failure to recognize and isolate suspected TB cases and provide adequate anti-TB treatment has resulted in outbreaks of MDR TB in U. S. health care settings and correctional facilities among HIV-infected individuals and their care-givers. MDR TB has frequently and rapidly led to death in HIV-infected individuals. To date, the number of cases of drug-resistant TB reported in Canada has been small, outbreaks of MDR TB have not been reported and there is only one report of an individual being co- infected with HIV and MDR TB. However, the possibility of MDR TB must always be considered in patients who were born in countries reporting high levels of drug-resistant TB or people who have lived or visited areas that have high levels of drug-resistant TB.
The National Reference Centre for Tuberculosis is part of the Bureau of Microbiology, LCDC. The Reference Centre was started in 1968 above a boiler room at the Royal Ottawa Sanatorium, which is now the Royal Ottawa Hospital, as a direct result of a recommendation of the "Third National Tuberculosis Conference", in 1966. This national conference was sponsored by the Department of National Health and Welfare, the Canadian Tuberculosis and Respiratory Diseases Association (now the Canadian Lung Association), and the provincial directors of TB control. The purpose of the recommendation was to establish a Central Laboratory for the purpose of centralizing the establishment and maintenance of methods in the TB laboratory. The initial staff included three persons and some of the earliest activities involved drug sensitivity testing for the primary drugs (INH, Streptomycin and PAS). The Laboratory also confirmed that isolates were M. tuberculosis. Services and research studies were expanded over the years to include the identification of the atypical or opportunistic mycobacteria (now 54 sub-species). The Laboratory introduced the drug susceptibility testing method by Canetti for the second-line drugs (Ethambutol, Ethyonimide, Capriomycin). The Laboratory also evaluated Rifampin, which was becoming available, and the Rifampin-Ethambutol combination for the treatment of what was then chronic pulmonary TB resistance to the primary drugs. Other efficacy studies included INH-Rifampin, INH-Rifampin- Streptomycin, and INH-Rifampin-Ethambutol. The Laboratory subsequently became involved in metabolic studies of INH such as INH phenotyping and acetylation. These studies included monitoring serum levels of anti-TB drugs for provincial laboratories. Current staff include six full-time and two term employees. The six full-time employees range from a research scientist (Dr. Laszlo) to a bio-chemist and technicians. With the addition of more research and applied-science activities, the Laboratory was able to develop a single total drug sensitivity testing method for all of the drugs (the Canadian single-step method). The Laboratory also developed the radiometric method for drug susceptibility testing of the M. tuberculosis complex, using the Bactec 460 in 1981. As a result, every province now uses the Bactec method. The Laboratory also developed the radiometric method for the preliminary identification of M. tuberculosis directly from a clinical specimen with substantial savings in technician time compared to the conventional method. On an international level, the Laboratory has cooperated with Poland on drug susceptibility testing, including training in the methodology. A study on INH in collaboration with South Africa, revealed that there are certain human phenotypes that acetylize INH very fast, with inactiviation of the drug before it can act against M. tuberculosis. In 1980, the Laboratory was designated by WHO as one of three global collaborating centres for TB bacteriology. At present the Laboratory is the only remaining one. Dr. Laszlo continues as the director of the Centre. Six international training courses have been conducted over the years from 1985 to 1993. This very intense six-week course includes both lectures and hands-on-training in the Laboratory for 10 students. A total of 60 students from throughout the world have been trained, including from Asia, Africa, the Caribbean, and Europe. In addition, four protocols were developed for collaborative studies in South-America. Two of them involve quality assurance control of smear microscopy: one studies drug resistance patterns, and the other one was to identify all the mycobacterial species. A global resistance study focused on the region of the Americas and included Argentina, Mexico, Costa Rica, Peru, Cuba, Chile, and Colombia. The Laboratory also conducted a quality control drug resistance susceptibility test in Ethiopia. In collaboration with WHO, the Laboratory still continues to assist globally: on a consulting basis, and by training managerial and technical personnel. There are now a number of projects in the Dominican Republic and Nicaragua. The Laboratory is available for any Fellowships. In 1975, the Laboratory participated in the first national drug resistance survey and initiated one of the first national proficiency testing programs for all laboratories, using both conventional and Bactec methodologies. With the collaboration of other federal institutions and private companies (e.g., Becton Dickinson), the Laboratory undertook additional studies, such as a study for NAP, a drug that is added to be able to differentiate M. tuberculosis complex from anything else quickly in about four days. A study was completed with Agriculture Canada using Bactec for the identification of M. bovis. A multi-centre study with Adria Pharmaceutical examined anasamycin, (Rifabutin) for use in treating M. avium intracellulare. A study for the province of Quebec on case- finding in their aboriginal population used conventional and radiometric methods. Throughout this time, part of the Laboratory's role was the dissemination of technology to all of the provinces. Training was provided in all the methodologies. The Laboratory has developed an ELISA diagnosis test for the detection of TB using a synthetic cord factor. A multi-centre study for a radiometric method for the use of second-line drugs, particularly those antibiotics that can be used in the treatment of M. avium intracellulare, was completed and the technology has been transferred to the provinces. The Laboratory is in the third phase of a multi-centre study with laboratories in the United States for the development of a second-line drug for the treatment of MDR strains of TB. Abbott Pharmaceuticals is sponsoring a United States-Canada study on the use of clarithromycin for the treatment of M. avium intracellulare using radiometric technology. The Laboratory will continue its core capacity as the National Reference Centre within LCDC in support of all the provincial public health TB laboratories.
|
 |
|||
|
Last Updated: 1996-09-24 |  |
|
