Download Tuberculosis

Tuberculosis
The evolution of a bacterium
• World Health Organization (WH.O. declared TB a
global health emergency in 1993
• one–third of the world's current population has
been infected with M. tuberculosis
• new infections occur at a rate of one per second
• 2004 statistics: 14.6 million chronic active cases,
8.9 million new cases, and 1.6 million deaths,
mostly in developing countries
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• caused by Mycobacterium tuberculosis
• usually attacks the lungs, destroying lung
tissue
• can also infect the nervous system, skin,
bone, joints…
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Spread
• through the air, when people who have
the disease cough, sneeze, or spit
– inhalation of a single bacterium can cause an
infection
• most infections in human beings will be
asymptomatic and latent
• about one in ten latent infections will
eventually progress to active disease,
which, if left untreated, kills more than half
of its victims
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The Difference between Latent
TB Infection and TB Disease
A Person with Latent TB Infection
A Person with TB Disease
• Has no symptoms
• Has symptoms that may include:
- a bad cough that lasts 3 weeks or longer
- pain in the chest
- coughing up blood or sputum
- weakness or fatigue
- weight loss
- no appetite
- chills
- fever
- sweating at night
• Does not feel sick
• Usually feels sick
• Cannot spread TB bacteria to others
• May spread TB bacteria to others
• Usually has a skin test or blood test
result indicating TB infection
• Usually has a skin test or blood test
result indicating TB infection
• Has a normal chest x-ray and a
negative sputum smear
• May have an abnormal chest x-ray, or
positive sputum smear or culture
• Needs treatment for latent TB infection
to prevent active TB disease
• Needs treatment to treat active TB
disease
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Symptoms
• symptoms include chest pain, coughing up blood,
and a productive, prolonged cough for more than
three weeks
• systemic symptoms include fever, chills, night
sweats, appetite loss, weight loss, pallor, and
often a tendency to fatigue very easily
– as the disease progresses lung tissue is replaced by
scar tissue
• non-pulmonary TB causes all kinds of symptoms
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Risk Factors
• chronic conditions: diabetes, cancer, renal
failure, immunosuppression
• low body weight
• HIV
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Diagnosis
• usually a tuberculin skin test followed by
an X-ray to see if the infection is active
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Life Cycle
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• Following inhalation the bacterium can
reside in lung tissue for decades without
becoming active
• During a time of immunological stress the
bacterium can begin to multiply, forming
granulomas and destroying lung tissue, as
well as spreading through the rest of the
body
– Granulomas contain the slowly diving bacteria
as long as immune cells are healthy
– Detectable by X-ray
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TB in Canada (2007)
• 1,547 new active and re-treatment tuberculosis
(TB) cases (a rate of 4.7 per 100,000 population)
• foreign-born individuals accounted for 66% of all
reported TB cases in Canada
– Canadian-born non-Aboriginal and Canadian-born
Aboriginal cases made up 11% and 20%,
– TB rate in the Canadian-born Aboriginal group
continues to be the highest of the three groups,
approximately five times the overall Canadian rate.
• pulmonary TB represents 65% of all reported
cases
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Treatment
• people with latent infections will develop
TB when it overwhelms their immune
system (10%)
• ISOLATION! (forced in North America)
• antibiotics, usually a combination, 6-12
months
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Public Health
• requirement to report
• education of patients
• isolation
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Current Problems with TB
• Drug resistance: due to improper
treatment there are drug-resistant strains
of TB
• Increase in TB cases in Canada’s
Aboriginal peoples
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Prevention
• BCG vaccine is somewhat effective in
children (used in South Africa)
• people with latent infections are treated to
prevent active TB
• Patient education instructional video
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