Tuberculosis

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Tuberculosis

• The evolution of a bacterium

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• World Health Organization (WH.O. declared TB a
  global health emergency in 1993
• onethird 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

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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