A Blight on Vancouver: a Tuberculosis FAQ


First of all, what is tuberculosis?

Tuberculosis is a disease caused by Mycobacterium tuberculosis, a bacteria which attacks the immune system, living and replicating inside of white blood cells (5). In most cases the immune system is able to keep the initial infection (Primary Tuberculosis) with M. tuberculosis at bay (6). This resultant non-active form is called a latent tuberculosis infection (or LTBI) (6) and it is not contagious or symptomatic. 10% of all people with LTBI develop into active TB, which is both contagious and symptomatic (in most cases) (8).

How is it spread and what are the symptoms?

When someone with active pulmonary or lung TB coughs, they expel M. tuberculosis –containing droplets into the air, which can infect a person who breathes them in (7). The symptoms can include loss of appetite, weight loss, fatigue, fever and night sweats. In most cases the disease is in the lungs and manifests itself as a cough with sputum, (4) although almost every body system can be affected so that TB has been called a great mimic of other diseases (5).

Why is diagnosis necessary?

The danger of asymptomatic LTBI is that it can progress into the infectious form of TB at any time, although it is much more likely if the immune system is compromised (2) (for example if the individual is infected with HIV – a virus that targets and weakens the immune system) (5). Confirmation of active TB and detection of LTBI can be done with several tests. It is very important to screen people at risk for LTBI because it not only protects the person who could develop TB but also protects the public from a potential outbreak (6). Those at high risk stand to be benefit the most from LTBI diagnosis and treatment (6).

How is tuberculosis diagnosed?

The first test is the tuberculin skin test (or TST), which involves the injecting of a purified protein isolated from M. tuberculosis just underneath the skin (7). If the person is infected (LTBI or TB) there will be swelling at that site which is the immune system’s way of saying ‘I’ve seen this mycobacterium before’ (5). In order to test specifically for TB, the organism has to be either grown or isolated in this case from sputum, especially if accompanied by appropriate chest X-ray findings (7). Sputum smear positive patients are especially contagious and therefore it is very crucial to screen them (9).

What is the treatment?

Families of antibiotics kill the bacteria in a particular way (5). Since there are very large amounts of bacteria in an infected host, the chances are that some of the bacteria have a particular mutation making them resistant to a particular antibiotic (5). If only one antibiotic is given to bacteria with a high chance of mutation then it is very likely the antibiotic will ‘select’ for the antibiotic resistant strain of bacteria, allowing that organism to flourish. In order to combat antibiotic resistance the treatment for TB involves a strict 6-9 month regiment of several antibiotics (7). It is important that ALL of the medication be taken and for the WHOLE time or antibiotic resistance will emerge (7). LTBI can be suppressed from developing into TB with treatment by only one antibiotic (3). Highly successful adherence programs put forth by the WHO and implemented across Canada include Directly Observed Therapy (DOT) for TB and Directly Observed Preventative Therapy (DOPT) for LTBI. These programs will be referred to as DOT for the rest of this paper and include direct observation of the TB medications being taken as well as provision of TB education to the patients (4,7).

What are MDR-TB, XDR-TB and TDR-TB?

MDR-TB (Multi-Drug Resistant), XDR-TB (Extensively Drug Resistant) and TDR-TB (Totally Drug Resistance) are the result of antibiotic resistance. These strains of TB carry a much higher mortality and are more expensive to treat (an average of $400,000 per patient in comparison to regular TB which averages $1200 per patient) (5).

How prevalent is the disease in the world?

TB is known as the world’s second largest killer due to either bacteria or virus (4). It is estimated that one third of the world’s population has been infected with the latent form of TB – the world-wide prevalence (6). Incidence, defined as the number of new cases per 100,000 people in a population provides a more dynamic measure (5).  In 2006, The World Health Organization (WHO) estimated incident rates of active TB at 139/100,000 worldwide; with the highest incidence among 12 African countries at 363/100,000 (1).

What is the world doing to deal with this global issue?

The WHO’s Stop TB strategy aims to halve TB prevalence and deaths by 2015 and decrease incidence to less than 1/million by 2050 (1). To achieve this goal, the WHO plans to detect 70% of active TB and treat 85% of these cases worldwide (1).

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So, what about Canada?

In Canada, the incidence rates average between 2005-2008 are much lower that world incidence rates, with a nation-wide 4.85/100,000, a B.C rate of 7.1/100,000 and the comparatively daunting Downtown Eastside (DTES) of Vancouver rate of 36.4/100,000 (10). This much larger incidence rate is due to the contribution of TB among the homeless, in whom the incidence is 25-100 times higher than in the general population (11).

Why are TB rates in the homeless so high?

There are two distinct but highly connected reasons the TB rates are so high in the homeless. Firstly, the chances of contracting LTBI increase with overcrowded living conditions, poor ventilation and the frequency and length of exposure to patients with active TB (8). While 10% of people with LTBI in the general population will develop active TB; the much greater prevalence of HIV infection, IV drug use, malnutrition and other health conditions that weaken the immune system among the homeless make the chances of LTBI transforming into active TB and even initial infection much higher in this population (8). One in five homeless people die within a year of active TB diagnosis (14) thus it is important to prevent the progression of LTBI to active TB.

What are HEAT shelters?

HEAT stands for Homeless Emergency Action Team, a program that was launched on December 9th 2008 to create temporary shelters for the coldest 90 days (ending on March 31st ) of each year) (12). The largest of these make-shift shelters is the First United Church (12), which comprises 55% of all the shelter bed space in the city of Vancouver (200 people at capacity but frequently surpasses this limit) (13). This year (2012) is the last year that the HEAT shelters are remaining open (for controversial reasons), with First United having extended it’s opening until July 31st (13).

That sounds amazing… what’s the catch?

At First United shelter and shelters like it, people live in close quarters with one another and therefore infection rates are very high (14). First United shelters more people than any other in the downtown core and is thus the most prone to TB outbreaks and for this reason, is being used as a model in this paper. That being said there are many other permanent emergency shelters with large capacities including the Catholic Charities Men’s Hostel (102 people) and the Belkin House (70 people) (17). All it takes is one active TB patient to go unnoticed in a homeless shelter for an outbreak of 30 active cases and thousands of contacts (like the outbreak in Kelowna) to occur (15).

What makes the issue of TB spreading in the homeless community worse now than ever before?

For one thing, in the recent 2011 homeless count, the proportion of people reporting one health condition increased from 27% to 38%, and reporting multiple conditions from 35% to 62% over the past six years (16). Since other health conditions can drastically increase the chances of progression of LTBI to active TB the trends over the past six years point to a seemingly imminent TB outbreak. With resistant TB strains becoming more prevalent, the prospect of MDR-TB or XDR-TB entering a shelter (First United Church for example) is truly frightening and would, as predicted by Toronto’s Dr. Kamran Khan, be difficult to control (14).

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What are some Canada wide laws in regards to TB?

Every province and territory requires the reporting of active TB and has legislation that if voluntary adherence to active TB diagnosis and treatment is not taken, involuntary detention can occur (9). In Canada, the detained person can only be kept until the TB is no longer contagious meaning the previously non-adherent person has not finished their treatment and is not required by law to do so (9). As mentioned above, antibiotic resistant strains are acquired via incomplete treatment, so it appears that this law is not severe enough as it’s lenience allows for the development of antibiotic resistant strains.

What are some successful policies that Tuberculosis Prevention and Control, Public Agency of Canada, the Canadian Lung Association and the BC Centre for Disease Control have agreed on and implemented?

First and foremost, TB medications for both forms of TB are publicly funded nation-wide (9). A more recent suggestion is the co-ordination of TB and HIV/AIDS programs which could make treatment more efficient (this will be discussed in a later section) (9). Implementation of engineering advances such as improved ventilation and providing masks is also promoted (9). DOT is another successful policy and has notably increased adherence (7).

Why are contact investigation policies ineffective in homeless communities?

A contact investigation is required by law and involves public health staff ensuring that all contacts of active TB are identified and tested (9). The procedure in the regular population involves lab work of the patient, identification of close contacts, interviews, close contacts with symptoms closely analyzed, treatment of LTBI in contacts and repetition of TST 8 weeks after an initially negative TST for close contacts (9). There are many challenges in conducting these investigations in homeless communities; by definition they have no fixed address and usually no telephone. They often cannot identify their social contacts by name, are mistrustful of the health system and are therefore less likely to come forward for treatment (9). All of these factors cause a delay in treatment (9).

What are policies in regards to screening for TB in homeless shelters?

Screening in shelters targets cases of active TB and not LTBI, and is usually triggered in response to an infectious case rather than beforehand as a preventative measure (9). In 2004, the CDC and the Institute of Medicine in the United States recommended identifying and treating people with LTBI in high-risk populations (19). In a recent study of Tarrant County’s TB system, the total societal costs of active TB were calculated to be around $375,000, while the costs of the homeless screening and treatment program (not including start-up costs) was only $14,350 per case prevented (20). Clearly BC policy in regards to LTBI screening and treatment needs to be changed.

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How can involuntary detention laws be modified?

As mentioned above, Canadian laws require the noncompliant active TB patient to be released as soon as the TB is no longer contagious giving rise to problems such as antibiotic resistant strains, carried by individuals who are free to spread them in their (often homeless) communities (9). In the United States, the Advisory Council for the Elimination of Tuberculosis recommended that a noncompliant patient be detained until they have completed treatment or been cured; this is the case in seven states (18).

How could mandatory homeless shelter screening be implemented successfully?

Currently, in Adult Licensed Residential community care facilities, all residents must complete testing before admission or within 1 month if they aren’t symptomatic (9). This testing involves a TST, which if positive warrants a CXR (chest x-ray) and symptom analysis. If either of the latter two is abnormal, sputum is collected and tested (9). This same process could be implemented in BC homeless shelters and actually has been put in effect in Texas’ Tarrant County (19). In Tarrant County, in order for someone to stay in a shelter they are issued a yellow TB card which is valid for 30 days, if by then they have not had their TB tests and results they are no longer sheltered. Once tests are completed they are issued white ‘permanent’ cards which expire after one year (22). The outcome of this program is a large decrease in TB death rates and reduction in societal costs, as detailed below (21). At each of the four Tarrant County shelters, on-site symptom checks, CXR, TST and medical evaluation are undertaken with DOT staff available 5 hours 5 times a week (19). If Vancouver wants to implement a mandatory program it should follow this structure. This would require the presence of TB treatment and screening facilities be on-site at the major shelters.

I’m skeptical, how do I know that their program even worked?

Before Tarrant County’s program was implemented only 5.3% of active TB cases were detected by their existing voluntary screening method, the other 94.7% was detected in hospitals, meaning the vast majority of patients had remained in the congested shelter system while contagious (21). After the mandatory program was implemented significantly more active TB cases were found (for every 82 screened, 1 had TB) and in addition many LTBI cases were found (for every 4.5 people screened, 1 had LTBI) (19).  In a recent study of Tarrant County’s system it was calculated that for every 12 patients treated with LTBI (that had mandatory screening) 1 active case would be prevented with a total cost of $14,000 per case prevented (not including start up costs) (19). A later study suggests that each active TB case in Tarrant County costs around $375,000, factoring in all costs to society, including infrastructure costs, inpatient and outpatient treatment of TB and LTBI, death and secondary transmission costs (20). Not only is proactive LTBI screening and treatment economically viable; but it also prevents the disease from spreading and lowers TB mortality rates (21).

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In order to change involuntary detention laws or to implement a mandatory LTBI screening and treating program what must be done?

Governments make laws and need to be persuaded by research. Further research into the flaws of the current system and the benefits of the new system must be made as well as advocacy campaigns to funders of current TB programs (largely the government).

What further research must be done?

Firstly, we need research into LTBI treatment adherence in downtown Vancouver. In San Francisco, for example, the median LTBI treatment adherence was only 2 months (the full treatment ranging from 6-9 months) (19). Secondly, the economic impact of TB in the Vancouver downtown environment is likely to mirror that of Tarrant County (in Tarrant County $14,000 screening and prevention costs saved $375,000 in active TB repercussions) (20). While it is understood that some governments only have a memory of four years, any government could be made to understand that these financial benefits will accrue during that time. Research into the specific social costs of an active TB case in Vancouver would highlight what the government stands to gain. Tarrant County is but one effective program; a review of many mandatory LTBI screening and treating programs in high-risk populations could lend an even more powerful message to the government.

Who exactly would this new research be targeting?

Currently the leaders in TB care in BC are the BCCDC, the Canadian Lung Association, Vancouver Coastal Health (9,23,24). The BCCDC is a part of the Provincial Health Services Authority, which receives funding from BC ministry of Health but in some cases funds specialized programs itself (24). Vancouver Coastal Health also receives most of its funding from the Ministry of Health (23), therefore targeting the British Columbia government’s Ministry of Health should be the highest priority. An appreciation of the proportion of aboriginal or HIV subpopulations within the homeless community may serve both to garner federal funds and raise awareness.

With the current and future research how can the Ministry of Health actually be contacted?

Just getting the information out into the public is a major barrier. By raising awareness of the issues with TB in the homeless and explaining the potential solution through various forms of media people can be reached. An important and realistic way to raise awareness to the government about concern and a potential solution is through advocacy groups such as Results Canada, a Canada-wide advocacy network with local groups in various cities (25). These groups provide a forum for like-minded individuals to plan awareness initiatives as well as to co-ordinate letter-writing campaigns. As of right now there is no Results group in Vancouver, let alone on the UBC campus, so there exists an opportunity for a student to assemble such a group in an effort to start change in TB policy in the homeless of Vancouver.

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  1. Lonnroth, Knut and Mario Raviglione. “Global Epidemiology of Tuberculosis: Prospects for Control.” Seminars in Respiratory and Critical Care Medicine 29.5 (2008): 481-491. Print.
  2. Healthwise Staff. Tuberculosis (TB) Disease. HealthLink BC File #51a. Web. Sept 2007. < http://www.healthlinkbc.ca/healthfiles/hfile51a.stm>
  3. Healthwise Staff. Multiple-Drug Therapy for Tuberculosis (TB). HealthLink BC. Web. June 16 2011. <http://www.healthlinkbc.ca/kb/content/drugdetail/hw207157.html>.
  4. WHO Media Centre. “Tuberculosis Fact sheet N˚104”. World Heath Organization. Web. March 2012.  <http://www.who.int/mediacentre/factsheets/fs104/en/>.
  5. Kion, Tracy. Introductory Medical Microbiology and Immunology, 2011W Term 2. Pearson. Rpt. in Custom course Materials MICB 202. Department of Microbiology and Immunology. University of British Columbia. 2011. Print.
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  7. Canada. Health Canada, British Columbia Centre for Disease Control. Directly Observed Therapy (DOT) Manual for Tuberculosis Programs in British Columbia. Compiled by Shawna Buchholz. April MacNaughton, CDC Coordinator. Health Canada, 2011. Web.
  8. Francis J. Curry National Tuberculosis Center. Shelters and TB: What Staff Need to Know, Second Edition. January 2008. Web.
  9. Canada. Public Health Agency of Canada. Canadian Tuberculosis Standards, Sixth Edition. Published by Authority of the Minister of Health. 2007. Web.
  10. Canada. British Columbia Centre for Disease Control. Tuberculosis Control 2005,2006,2007,2008 Annual Report. Provincial Director Dr. R.K. Elwood. 2008. Web.
  11. Canada. Vancouver Coastal Health. A Mental Health & Addictions Supported Housing Framework, Draft. April 2006. Web.
  12. Office of the Mayor. Update on the Emergency Action Team. Vancouver. Web. Jan 2009. <http://vancouver.ca/heat/mayors_update_jan22_2009.htm>.
  13. First United Blog. A Place of Refuge. First United Church. Web. n.d. <http://firstunited.ca/what-we-do/shelte/>.
  14. Khan, Kamran, et al. “Active Tuberculosis among Homeless Persons, Toronto, Ontario, Canada, 1998-2007.”Emerging Infectious Diseases 17.3 (2011): 357-365. Print.
  15. Canada. Medical Health Officers Update for Physicians. TB Outbreak Among the Homeless In Kelowna. Senior Medical Health Officer Dr. Andrew Larder. Interior Health. March 2011. Web.
  16. Vancouver. Regional Steering Committee on Homelessness. One Step Forward: Results of the 2011 Metro Vancouver Homeless Count. Alice Sundberg and Susan Papadionissiou, Co-Chairs. Metro Vancouver. Feb 2012. Web.
  17. British Columbia. How to Access Emergency Shelters. BC Housing. Web. n.d. <http://www.bchousing.org/Options/Emergency_Housing/ESP>.
  18. United States. Tuberculosis Control Laws – United States, 1993 Recommendations of the Advisory Council for the Elimination of Tuberculosis (ACET). Centre for Disease Control. Nov 1993. Web.
  19. Miller, L. Thaddeus, et al. “Using Cost and Health Impacts to Prioritize the Targeted Testing of Tuberculosis in the United States. “ Annals of Epidemiology 16.4 (2006): 305-312. Print.
  20. Miller, L. Thaddeus, et al. “The Societal Cost of Tuberculosis: Tarrant County, Texas, 2002.” Annals of Epidemiology 20.1 (2010): 1-7. Print.
  21. United States. Targeted Tuberculosis Screening in Response to a Retrospective Analysis of Genotyping Data and Geographic Information System Data. Tarrant County Public Health Department. The National Association of County and City Health Officials. 2004. Web.
  22. Tarrant County. HMIS Scan Cards. Tarrant County Homeless Coalition. Web. <http://www.ahomewithhope.org/homeless-resources/tbhmis-scan-cards.aspx>.
  23. Canada. British Columbia. 2011/12 -2013/14 Service Plan. C.C. Woodward, Board Chair. Vancouver Coastal Health. Oct 2011. Web.
  24. Canada. British Columbia. 2011/12-2013/14 Service Plan. G.W. Powell, Board Chair. Provincial Health Services Authority. Oct 2011. Web.
  25. Advocate Tools. Results Canada. Web. n.d. < http://www.results-resultats.ca/Tools/index_eng.asp>.

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Daniel Raff is a 'budding' Microbiology and Immunology student with a vivid imagination. He regularly finds himself wondering about outbreaks and after hearing of a UBC researchers TB outbreak analysis, this FAQ was the result.

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Daniel Raff is a 'budding' Microbiology and Immunology student with a vivid imagination. He regularly finds himself wondering about outbreaks and after hearing of a UBC researchers TB outbreak analysis, this FAQ was the result.